Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. SYMBYAX is not approved for the treatment of patients with dementia-related psychosis [see Boxed Warning and Use in Specific Populations (8.5)].

In olanzapine placebo-controlled clinical trials of elderly patients with dementia-related psychosis, the incidence of death in olanzapine-treated patients was significantly greater than placebo-treated patients (3.5% vs 1.5%, respectively).

Meta-Analysis of Antipsychotic Use in Dementia-Related Psychosis — Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Analyses of seventeen placebo-controlled trials (modal duration of 10 weeks), largely in patients taking atypical antipsychotic drugs, revealed a risk of death in drug-treated patients of between 1.6 to 1.7 times the risk of death in placebo-treated patients. Over the course of a typical 10-week controlled trial, the rate of death in drug-treated patients was about 4.5%, compared to a rate of about 2.6% in the placebo group. Although the causes of death were varied, most of the deaths appeared to be either cardiovascular (e.g., heart failure, sudden death) or infectious (e.g., pneumonia) in nature. Observational studies suggest that, similar to atypical antipsychotic drugs, treatment with conventional antipsychotic drugs may increase mortality. The extent to which the findings of increased mortality in observational studies may be attributed to the antipsychotic drug as opposed to some characteristic(s) of the patients is not clear. SYMBYAX (olanzapine and fluoxetine) is not approved for the treatment of patients with dementia-related psychosis [see Use in Specific Populations (8.5)].

Cerebrovascular Adverse Events (CVAE), Including Stroke — Cerebrovascular adverse events (e.g., stroke, transient ischemic attack), including fatalities, were reported in patients in trials of olanzapine in elderly patients with dementia-related psychosis. In placebo-controlled trials, there was a significantly higher incidence of cerebrovascular adverse events in patients treated with olanzapine compared to patients treated with placebo. Olanzapine and SYMBYAX are not approved for the treatment of patients with dementia-related psychosis [see Boxed Warning].

Hyperglycemia and Diabetes Mellitus

Adults — Healthcare providers should consider the risks and benefits when prescribing SYMBYAX to patients with an established diagnosis of diabetes mellitus, or having borderline increased blood glucose level (fasting 100-126 mg/dL, nonfasting 140-200 mg/dL). Patients taking SYMBYAX should be monitored regularly for worsening of glucose control. Patients starting treatment with SYMBYAX should undergo fasting blood glucose testing at the beginning of treatment and periodically during treatment. Any patient treated with atypical antipsychotics should be monitored for symptoms of hyperglycemia including polydipsia, polyuria, polyphagia, and weakness. Patients who develop symptoms of hyperglycemia during treatment with atypical antipsychotics should undergo fasting blood glucose testing. In some cases, hyperglycemia has resolved when the atypical antipsychotic was discontinued; however, some patients required continuation of anti-diabetic treatment despite discontinuation of the suspect drug.

Hyperglycemia, in some cases extreme and associated with ketoacidosis or hyperosmolar coma or death, has been reported in patients treated with atypical antipsychotics, including olanzapine alone, as well as olanzapine taken concomitantly with fluoxetine. Assessment of the relationship between atypical antipsychotic use and glucose abnormalities is complicated by the possibility of an increased background risk of diabetes mellitus in patients with schizophrenia and the increasing incidence of diabetes mellitus in the general population. Epidemiological studies suggest an increased risk of treatment-emergent hyperglycemia-related adverse reactions in patients treated with the atypical antipsychotics. While relative risk estimates are inconsistent, the association between atypical antipsychotics and increases in glucose levels appears to fall on a continuum and olanzapine appears to have a greater association than some other atypical antipsychotics.

Mean increases in blood glucose have been observed in patients treated (median exposure of 9.2 months) with olanzapine in phase 1 of the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE). The mean increase of serum glucose (fasting and nonfasting samples) from baseline to the average of the 2 highest serum concentrations was 15.0 mg/dL.

In a study of healthy volunteers, subjects who received olanzapine (N=22) for 3 weeks had a mean increase compared to baseline in fasting blood glucose of 2.3 mg/dL. Placebo-treated subjects (N=19) had a mean increase in fasting blood glucose compared to baseline of 0.34 mg/dL.

In an analysis of 7 controlled clinical studies, 2 of which were placebo-controlled, with treatment duration up to 12 weeks, SYMBYAX was associated with a greater mean change in random glucose compared to placebo (+8.65 mg/dL vs. -3.86 mg/dL). The difference in mean changes between SYMBYAX and placebo was greater in patients with evidence of glucose dysregulation at baseline (including those patients diagnosed with diabetes mellitus or related adverse reactions, patients treated with anti-diabetic agents, patients with a baseline random glucose level ≥200 mg/dL, or a baseline fasting glucose level ≥126 mg/dL). SYMBYAX-treated patients had a greater mean HbA_1c increase from baseline of 0.15% (median exposure 63 days), compared to a mean HbA_1c decrease of 0.04% in fluoxetine-treated subjects (median exposure 57 days) and a mean HbA_1c increase of 0.12% in olanzapine-treated patients (median exposure 56 days).

In an analysis of 6 controlled clinical studies, a larger proportion of SYMBYAX-treated subjects had glycosuria (4.4%) compared to placebo-treated subjects (1.4%).

The mean change in nonfasting glucose in patients exposed at least 48 weeks was +5.9 mg/dL (N=425).

Table 2 shows short-term and long-term changes in random glucose levels from adult SYMBYAX studies.

In a 47-week SYMBYAX study, the mean change from baseline to endpoint in fasting glucose was +4.81 mg/dL (n=130). Table 3 shows the categorical changes in fasting glucose [see Clinical Studies (14.2)].

Controlled fasting glucose data is limited for SYMBYAX; however, in an analysis of 5 placebo-controlled olanzapine monotherapy studies with treatment duration up to 12 weeks, olanzapine was associated with a greater mean change in fasting glucose levels compared to placebo (+2.76 mg/dL vs. +0.17 mg/dL).

The mean change in fasting glucose for olanzapine-treated patients exposed at least 48 weeks was +4.2 mg/dL (N=487). In analyses of patients who completed 9-12 months of olanzapine therapy, mean change in fasting and nonfasting glucose levels continued to increase over time.

Children and Adolescents — In a single, 8-week, randomized, placebo-controlled clinical trial investigating SYMBYAX for treatment of bipolar I depression in patients 10 to 17 years of age, there were no clinically meaningful differences observed between SYMBYAX and placebo for mean change in fasting glucose levels. Table 4 shows categorical changes in fasting blood glucose from the pediatric SYMBYAX study.

Olanzapine Monotherapy in Adolescents — In an analysis of 3 placebo-controlled olanzapine monotherapy studies of adolescent patients, including those with Schizophrenia (6 weeks) or Bipolar I Disorder (manic or mixed episodes) (3 weeks), olanzapine was associated with a greater mean change from baseline in fasting glucose levels compared to placebo (+2.68 mg/dL vs -2.59 mg/dL). The mean change in fasting glucose for adolescents exposed at least 24 weeks was +3.1 mg/dL (N=121). Table 5 shows short-term and long-term changes in fasting blood glucose from adolescent olanzapine monotherapy studies.

Dyslipidemia

Undesirable alterations in lipids have been observed with SYMBYAX use. Clinical monitoring, including baseline and periodic follow-up lipid evaluations in patients using SYMBYAX, is recommended.

Weight Gain

Potential consequences of weight gain should be considered prior to starting SYMBYAX. Patients receiving SYMBYAX should receive regular monitoring of weight.

Adults — Sedation-related adverse reactions were commonly reported with SYMBYAX treatment occurring at an incidence of 26.6% in SYMBYAX-treated patients compared with 10.9% in placebo-treated patients. Sedation-related adverse reactions (sedation, somnolence, hypersomnia, and lethargy) led to discontinuation in 2% (15/771) of patients in the controlled clinical studies.

Children and Adolescents — In a single, 8-week, randomized, placebo-controlled clinical trial investigating SYMBYAX for the treatment of bipolar I depression in patients 10 to 17 years of age, somnolence-related adverse events were commonly reported with SYMBYAX treatment occurring at an incidence of 23.5% in SYMBYAX-treated patients compared with 2.4% in placebo-treated patients. Somnolence-related adverse events led to discontinuation in 1.2% (2/170) of patients.

Adults — In controlled clinical studies of SYMBYAX (up to 12 weeks), changes from normal to high in prolactin concentrations were observed in 28% of adults treated with SYMBYAX as compared to 5% of placebo-treated patients. The elevations persisted throughout administration of SYMBYAX. In a pooled analysis from clinical studies including 2929 adults treated with SYMBYAX, potentially associated clinical manifestations included menstrual-related events¹ (1% [20/1946] of females), sexual function-related events² (7% [192/2929] of females and males), and breast-related events³ (0.8% [16/1946] of females, 0.2% [2/983] of males).

Children and Adolescents — In a single, 8-week, randomized, placebo-controlled clinical trial investigating SYMBYAX for the treatment of bipolar I depression in patients 10 to 17 years of age, SYMBYAX was associated with a statistically significant greater mean change from baseline in prolactin levels compared to placebo (8.7 mcg/L vs 0.7 mcg/L, respectively). Although prolactin concentrations were very commonly (>10%) elevated above normal in both the SYMBYAX and placebo groups, more than twice as many SYMBYAX-treated patients were seen with these elevations compared to placebo-treated patients. Five patients experienced an adverse event potentially associated with elevated prolactin; these events included dysmenorrhea, galactorrhea, and ovulation disorder.

The magnitude and frequency of change in prolactin in children and adolescents was larger than observed in adult patients treated with SYMBYAX, but was similar to that observed in adolescents treated with olanzapine monotherapy.

Olanzapine Monotherapy

In placebo-controlled olanzapine clinical studies (up to 12 weeks), changes from normal to high in prolactin concentrations were observed in 30% of adults treated with olanzapine as compared to 10.5% of adults treated with placebo. In a pooled analysis from clinical studies including 8136 adults treated with olanzapine, potentially associated clinical manifestations included menstrual-related events¹ (2% [49/3240] of females), sexual function-related events² (2% [150/8136] of females and males), and breast-related events³ (0.7% [23/3240] of females, 0.2% [9/4896] of males).

In placebo-controlled olanzapine monotherapy studies in adolescent patients (up to 6 weeks) with schizophrenia or bipolar I disorder (manic or mixed episodes), changes from normal to high in prolactin concentrations were observed in 47% of olanzapine-treated patients compared to 7% of placebo-treated patients. In a pooled analysis from clinical trials including 454 adolescents treated with olanzapine, potentially associated clinical manifestations included menstrual-related events¹ (1% [2/168] of females), sexual function-related events² (0.7% [3/454] of females and males), and breast-related events³ (2% [3/168] of females, 2% [7/286] of males), [see Use in Specific Populations (8.4)].

¹ Based on a search of the following terms: amenorrhea, hypomenorrhea, menstruation delayed, and oligomenorrhea.

² Based on a search of the following terms: anorgasmia, delayed ejaculation, erectile dysfunction, decreased libido, loss of libido, abnormal orgasm, and sexual dysfunction.

³ Based on a search of the following terms: breast discharge, enlargement or swelling, galactorrhea, gynecomastia, and lactation disorder.

Dose group differences with respect to prolactin elevation have been observed. In a single 8-week randomized, double-blind, fixed-dose study comparing 10 (n=199), 20 (n=200) and 40 (n=200) mg/day of oral olanzapine in adult patients with schizophrenia or schizoaffective disorder, incidence of prolactin elevation >24.2 ng/mL (female) or >18.77 ng/mL (male) at any time during the trial (10 mg/day: 31.2%; 20 mg/day: 42.7%; 40 mg/day: 61.1%) indicated significant differences between 10 vs 40 mg/day and 20 vs 40 mg/day.

Adults — The information below is derived from a clinical study database for SYMBYAX consisting of 2547 patients with treatment resistant depression, depressive episodes associated with Bipolar I Disorder, Major Depressive Disorder with psychosis, or sexual dysfunction with approximately 1085 patient-years of exposure. The conditions and duration of treatment with SYMBYAX varied greatly and included (in overlapping categories) open-label and double-blind phases of studies, inpatients and outpatients, fixed-dose and dose-titration studies, and short-term or long-term exposure.

Adverse Reactions Associated with Discontinuation of Treatment in Short-Term, Controlled Studies Including Depressive Episodes Associated with Bipolar I Disorder and Treatment Resistant Depression — Overall, 11.3% of the 771 patients in the SYMBYAX group discontinued due to adverse reactions compared with 4.4% of the 477 patients for placebo. Adverse reactions leading to discontinuation associated with the use of SYMBYAX (incidence of at least 1% for SYMBYAX and greater than that for placebo) using MedDRA Dictionary coding were weight increased (2%) and sedation (1%) versus placebo patients which had 0% incidence of weight increased and sedation.

Commonly Observed Adverse Reactions in Controlled Studies Including Depressive Episodes Associated with Bipolar I Disorder and Treatment Resistant Depression — In short-term studies, the most commonly observed adverse reactions associated with the use of SYMBYAX (incidence ≥5% and at least twice that for placebo in the SYMBYAX-controlled database) using MedDRA Dictionary coding were: disturbance in attention, dry mouth, fatigue, hypersomnia, increased appetite, peripheral edema, sedation, somnolence, tremor, vision blurred, and weight increased. Adverse reactions reported in clinical trials of olanzapine and fluoxetine in combination are generally consistent with treatment-emergent adverse reactions during olanzapine or fluoxetine monotherapy.

In a 47-week maintenance study in adults with treatment resistant depression, adverse reactions associated with SYMBYAX use were generally similar to those seen in short-term studies. Weight gain, hyperlipidemia, and hyperglycemia were observed in SYMBYAX-treated patients throughout the study.

Adverse Reactions Occurring at an Incidence of 2% or More in Short-Term Controlled Studies Including Depressive Episodes Associated with Bipolar I Disorder and Treatment Resistant Depression — Table 16 enumerates the treatment-emergent adverse reactions associated with the use of SYMBYAX (incidence of at least 2% for SYMBYAX and twice or more than for placebo). The SYMBYAX-controlled column includes patients with various diagnoses while the placebo column includes only patients with bipolar depression and major depression with psychotic features.

Extrapyramidal Symptoms

Dystonia, Class Effect for Antipsychotics — Symptoms of dystonia, prolonged abnormal contractions of muscle groups, may occur in susceptible individuals during the first few days of treatment. Dystonic symptoms include: spasm of the neck muscles, sometimes progressing to tightness of the throat, swallowing difficulty, difficulty breathing, and/or protrusion of the tongue. While these symptoms can occur at low doses, the frequency and severity are greater with high potency and at higher doses of first generation antipsychotic drugs. In general, an elevated risk of acute dystonia may be observed in males and younger age groups receiving antipsychotics; however, events of dystonia have been reported infrequently (<1%) with the olanzapine and fluoxetine combination.

Additional Findings Observed in Clinical Studies

Sexual Dysfunction — In the pool of controlled SYMBYAX studies in patients with bipolar depression, there were higher rates of the treatment-emergent adverse reactions decreased libido, anorgasmia, erectile dysfunction and abnormal ejaculation in the SYMBYAX group than in the placebo group. One case of decreased libido led to discontinuation in the SYMBYAX group. In the controlled studies that contained a fluoxetine arm, the rates of decreased libido and abnormal ejaculation in the SYMBYAX group were less than the rates in the fluoxetine group. None of the differences were statistically significant.

Sexual dysfunction, including priapism, has been reported with all SSRIs. While it is difficult to know the precise risk of sexual dysfunction associated with the use of SSRIs, healthcare providers should routinely inquire about such possible side effects.

There are no adequate and well-controlled studies examining sexual dysfunction with SYMBYAX or fluoxetine treatment. Symptoms of sexual dysfunction occasionally persist after discontinuation of fluoxetine treatment.

Difference Among Dose Levels Observed in Other Olanzapine Clinical Trials

In a single 8-week randomized, double-blind, fixed-dose study comparing 10 (N=199), 20 (N=200), and 40 (N=200) mg/day of olanzapine in patients with Schizophrenia or Schizoaffective Disorder, statistically significant differences among 3 dose groups were observed for the following safety outcomes: weight gain, prolactin elevation, fatigue, and dizziness. Mean baseline to endpoint increase in weight (10 mg/day: 1.9 kg; 20 mg/day: 2.3 kg; 40 mg/day: 3 kg) was observed with significant differences between 10 vs 40 mg/day. Incidence of treatment-emergent prolactin elevation >24.2 ng/mL (female) or >18.77 ng/mL (male) at any time during the trial (10 mg/day: 31.2%; 20 mg/day: 42.7%; 40 mg/day: 61.1%) with significant differences between 10 vs 40 mg/day and 20 vs 40 mg/day; fatigue (10 mg/day: 1.5%; 20 mg/day: 2.1%; 40 mg/day: 6.6%) with significant differences between 10 vs 40 and 20 vs 40 mg/day; and dizziness (10 mg/day: 2.6%; 20 mg/day: 1.6%; 40 mg/day: 6.6%) with significant differences between 20 vs 40 mg, was observed.

Other Adverse Reactions Observed in Clinical Studies

Following is a list of treatment-emergent adverse reactions reported by patients treated with SYMBYAX in clinical trials. This listing is not intended to include reactions (1) already listed in previous tables or elsewhere in labeling, (2) for which a drug cause was remote, (3) which were so general as to be uninformative, (4) which were not considered to have significant clinical implications, or (5) which occurred at a rate equal to or less than placebo.

Reactions are classified by body system using the following definitions: frequent adverse reactions are those occurring in at least 1/100 patients; infrequent adverse reactions are those occurring in 1/100 to 1/1000 patients; and rare reactions are those occurring in fewer than 1/1000 patients.

•   Body as a Whole — Frequent: chills, neck rigidity, photosensitivity reaction; Rare: death¹.
•   Cardiovascular System — Frequent: vasodilatation.
•   Digestive System — Frequent: diarrhea; Infrequent: gastritis, gastroenteritis, nausea and vomiting, peptic ulcer; Rare: gastrointestinal hemorrhage, intestinal obstruction, liver fatty deposit, pancreatitis.
•   Hemic and Lymphatic System — Frequent: ecchymosis; Infrequent: anemia, thrombocytopenia; Rare: leukopenia, purpura.
•   Metabolic and Nutritional — Frequent: generalized edema, weight loss; Rare: bilirubinemia, creatinine increased, gout.
•   Musculoskeletal System — Rare: osteoporosis.
•   Nervous System — Frequent: amnesia; Infrequent: ataxia, buccoglossal syndrome, coma, depersonalization, dysarthria, emotional lability, euphoria, hypokinesia, movement disorder, myoclonus; Rare: hyperkinesia, libido increased, withdrawal syndrome.
•   Respiratory System — Infrequent: epistaxis, yawn; Rare: laryngismus.
•   Skin and Appendages — Infrequent: alopecia, dry skin, pruritus; Rare: exfoliative dermatitis.
•   Special Senses — Frequent: taste perversion; Infrequent: abnormality of accommodation, dry eyes.
•   Urogenital System — Frequent: breast pain, menorrhagia², urinary frequency, urinary incontinence; Infrequent: amenorrhea², female lactation², hypomenorrhea², metrorrhagia², urinary retention, urinary urgency, urination impaired; Rare: breast engorgement².

¹ This term represents a serious adverse event but does not meet the definition for adverse drug reactions. It is included here because of its seriousness.

² Adjusted for gender.

Other Adverse Reactions Observed with Olanzapine or Fluoxetine Monotherapy

The following adverse reactions were not observed in SYMBYAX-treated patients during premarketing clinical studies but have been reported with olanzapine or fluoxetine monotherapy: Bruxism, dysuria, esophageal ulcer, gynecological bleeding, headache, hypotension, neutropenia, sudden unexpected death³ and sweating.

³ These terms represent serious adverse events but do not meet the definition for adverse drug reactions. They are included here because of their seriousness.

Children and Adolescent Patients (aged 10 to 17 years) with a Diagnosis of Bipolar Depression

The information below is derived from a single, 8-week, randomized, placebo-controlled clinical trial investigating SYMBYAX for the treatment of bipolar I depression in patients 10 to 17 years of age.

Adverse Reactions Associated with Discontinuation of Treatment in the single pediatric study — Overall, 14.1% of the 170 patients in the SYMBYAX group discontinued due to adverse reactions compared with 5.9% of the 85 patients for placebo. Adverse reactions leading to discontinuation associated with the use of SYMBYAX (incidence of at least 1% for SYMBYAX and greater than that for placebo) using MedDRA Dictionary coding were weight increased (2.9%), suicidal ideation (1.8%), bipolar disorder (1.2%), and somnolence (1.2%) versus placebo patients which had 0% incidence of weight increased, bipolar disorder, and somnolence, and a 1.2% incidence of suicidal ideation.

Adverse Reactions Occurring at an Incidence of 2% or more and greater than placebo — Table 17 enumerates the treatment-emergent adverse reactions associated with the use of SYMBYAX (incidence of at least 2% for SYMBYAX and twice or more than for placebo).

Vital Signs — Tachycardia, bradycardia, and orthostatic hypotension have occurred in SYMBYAX-treated patients [see Warnings and Precautions (5.11)]. The mean standing pulse rate of SYMBYAX-treated patients was reduced by 0.7 beats/min.

Laboratory Changes — In SYMBYAX clinical studies (including treatment resistant depression, depressive episodes associated with Bipolar I Disorder, Major Depressive Disorder with psychosis, or sexual dysfunction), SYMBYAX was associated with statistically significantly greater frequencies for the following treatment-emergent findings in laboratory analytes (normal at baseline to abnormal at any time during the trial) compared to placebo: elevated prolactin (28% vs 5%); elevated urea nitrogen (3% vs 0.8%); elevated uric acid (3% vs 0.5%); low albumin (3% vs 0.3%); low bicarbonate (14% vs 9%); low hemoglobin (3% vs 0%); low inorganic phosphorus (2% vs 0.3%); low lymphocytes (2% vs 0%); and low total bilirubin (15% vs 4%).

As with olanzapine, asymptomatic elevations of hepatic aminotransferases [ALT, AST, and GGT] and alkaline phosphatase have been observed with SYMBYAX. In the SYMBYAX-controlled database, clinically significant ALT elevations (change from <3 times the upper limit of normal [ULN] at baseline to ≥3 times ULN) were observed in 5% (38/698) of patients exposed to SYMBYAX compared with 0.5% (2/378) of placebo-treated patients and 4% (33/751) of olanzapine-treated patients. ALT elevations ≥5 times ULN were observed in 2% (11/701) of SYMBYAX-treated patients, compared to 0.3% (1/379) of placebo-treated patients and 1% (11/760) of olanzapine-treated patients. No patient with elevated ALT values experienced jaundice or liver failure, or met the criteria for Hy's Rule. ALT values returned to normal, or were decreasing, at last follow-up in the majority of patients who either continued treatment with SYMBYAX or discontinued SYMBYAX.

Rare postmarketing reports of hepatitis have been received in patients treated with olanzapine. Very rare cases of cholestatic or mixed liver injury have also been reported in the postmarketing period in patients treated with olanzapine.

Caution should be exercised in patients with signs and symptoms of hepatic impairment, in patients with pre-existing conditions associated with limited hepatic functional reserve, and in patients who are being treated with potentially hepatotoxic drugs.

An increase in creatine phosphokinase has been reported very rarely in SYMBYAX-treated patients and infrequently in clinical trials of olanzapine-treated patients.

Children and Adolescents (aged 10 to 17 years):

In a single 8-week randomized, placebo-controlled clinical trial investigating SYMBYAX for treatment of bipolar I depression in patients 10 to 17 years of age, the following was observed:

Vital Signs — In the SYMBYAX-treated patients compared with placebo-treated patients, the mean orthostatic blood pressure and standing pulse rate were not significantly different between treatment groups.

Body Weight: An increase in weight greater than or equal to 7% occurred in 52.4% of the SYMBYAX group and 3.6% of the placebo group. Weight gain greater than or equal to 15% occurred in 14.1% of the SYMBYAX group and none of the placebo group.

Laboratory Changes — SYMBYAX was associated with statistically significantly greater frequencies for the following treatment-emergent findings in laboratory analytes (normal or low at baseline to abnormal at any time during the trial) compared to placebo: elevated ALT (45.9% vs 2.5%); elevated AST (33.7% vs 7.6%); high fasting total cholesterol (28.9% vs 8.2%); high fasting LDL cholesterol (19.7% vs 6.5%); high fasting triglycerides (52.3% vs 27.3%), and elevated prolactin (85% vs 36%). No patient with elevated hepatic enzyme values experienced jaundice or liver failure, or met the criteria for Hy's Rule. Five patients experienced an adverse event potentially associated with elevated prolactin; these events included dysmenorrhea, galactorrhea, and ovulation disorder.

QT Interval Prolongation — SYMBYAX was associated with a statistically significantly greater mean increase in QT_cF interval (8.2 msec [95% CI 6.2, 10.2]) compared with placebo. No patients developed QT_c increases ≥60 msec or QT_c ≥480 msec [see Warnings and Precautions (5.20)].

Benzodiazepines — Co-administration of diazepam with olanzapine potentiated the orthostatic hypotension observed with olanzapine [see Drug Interactions (7.7)].

Inducers of 1A2 — Carbamazepine therapy (200 mg BID) causes an approximate 50% increase in the clearance of olanzapine. This increase is likely due to the fact that carbamazepine is a potent inducer of CYP1A2 activity. Higher daily doses of carbamazepine may cause an even greater increase in olanzapine clearance [see Drug Interactions (7.7)].

Alcohol — Ethanol (45 mg/70 kg single dose) did not have an effect on olanzapine pharmacokinetics [see Drug Interactions (7.7)].

Inhibitors of CYP1A2 — Fluvoxamine decreases the clearance of olanzapine. This results in a mean increase in olanzapine C_max following fluvoxamine administration of 54% in female nonsmokers and 77% in male smokers. The mean increase in olanzapine AUC is 52% and 108%, respectively. Lower doses of the olanzapine component of SYMBYAX should be considered in patients receiving concomitant treatment with fluvoxamine.

The Effect of Other Drugs on Olanzapine — Fluoxetine, an inhibitor of CYP2D6, decreases olanzapine clearance a small amount [see Clinical Pharmacology (12.3)]. Agents that induce CYP1A2 or glucuronyl transferase enzymes, such as omeprazole and rifampin, may cause an increase in olanzapine clearance. The effect of CYP1A2 inhibitors, such as fluvoxamine and some fluoroquinolone antibiotics, on SYMBYAX has not been evaluated. Although olanzapine is metabolized by multiple enzyme systems, induction or inhibition of a single enzyme may appreciably alter olanzapine clearance. Therefore, a dosage increase (for induction) or a dosage decrease (for inhibition) may need to be considered with specific drugs.

Pimozide — Concomitant use of SYMBYAX and pimozide is contraindicated. Pimozide can prolong the QT interval. SYMBYAX can increase the level of pimozide through inhibition of CYP2D6. SYMBYAX can also prolong the QT interval. Clinical studies of pimozide with other antidepressants demonstrate an increase in drug interaction or QT_c prolongation. While a specific study with pimozide and SYMBYAX has not been conducted, the potential for drug interactions or QT_c prolongation warrants restricting the concurrent use of pimozide and SYMBYAX [see Contraindications (4.2), Warnings and Precautions (5.20), and Drug Interactions (7.8)].

Carbamazepine — Patients on stable doses of carbamazepine have developed elevated plasma anticonvulsant concentrations and clinical anticonvulsant toxicity following initiation of concomitant fluoxetine treatment.

Alcohol — The coadministration of ethanol with SYMBYAX may potentiate sedation and orthostatic hypotension [see Drug Interactions (7.6)].

Thioridazine — Thioridazine should not be administered with SYMBYAX or administered within a minimum of 5 weeks after discontinuation of SYMBYAX, because of the risk of QT prolongation [see Contraindications (4.2), Warnings and Precautions (5.20), and Drug Interactions (7.8)].

In a study of 19 healthy male subjects, which included 6 slow and 13 rapid hydroxylators of debrisoquin, a single 25 mg oral dose of thioridazine produced a 2.4-fold higher C_max and a 4.5-fold higher AUC for thioridazine in the slow hydroxylators compared with the rapid hydroxylators. The rate of debrisoquin hydroxylation is felt to depend on the level of CYP2D6 isozyme activity. Thus, this study suggests that drugs that inhibit CYP2D6, such as certain SSRIs, including fluoxetine, will produce elevated plasma levels of thioridazine [see Contraindications (4.2)].

Thioridazine administration produces a dose-related prolongation of the QT_c interval, which is associated with serious ventricular arrhythmias, such as torsades de pointes-type arrhythmias and sudden death. This risk is expected to increase with fluoxetine-induced inhibition of thioridazine metabolism [see Contraindications (4.2)].

Due to the risk of serious ventricular arrhythmias and sudden death potentially associated with elevated thioridazine plasma levels, thioridazine should not be administered with fluoxetine or within a minimum of 5 weeks after fluoxetine has been discontinued [see Contraindications (4.2)].

Tricyclic Antidepressants (TCAs) — Single doses of olanzapine did not affect the pharmacokinetics of imipramine or its active metabolite desipramine.

In 2 fluoxetine studies, previously stable plasma levels of imipramine and desipramine have increased >2- to 10-fold when fluoxetine has been administered in combination. This influence may persist for 3 weeks or longer after fluoxetine is discontinued. Thus, the dose of TCA may need to be reduced and plasma TCA concentrations may need to be monitored temporarily when SYMBYAX is coadministered or has been recently discontinued [see Warnings and Precautions (5.6) and Clinical Pharmacology (12.3)].

Antihypertensive Agents — Because of the potential for olanzapine to induce hypotension, SYMBYAX may enhance the effects of certain antihypertensive agents [see Warnings and Precautions (5.11)].

Levodopa and Dopamine Agonists — The olanzapine component of SYMBYAX may antagonize the effects of levodopa and dopamine agonists.

Benzodiazepines — Multiple doses of olanzapine did not influence the pharmacokinetics of diazepam and its active metabolite N-desmethyldiazepam.

When concurrently administered with fluoxetine, the half-life of diazepam may be prolonged in some patients [see Clinical Pharmacology (12.3)]. Coadministration of alprazolam and fluoxetine has resulted in increased alprazolam plasma concentrations and in further psychomotor performance decrement due to increased alprazolam levels.

Clozapine — Elevation of blood levels of clozapine has been observed in patients receiving concomitant fluoxetine.

Haloperidol — Elevation of blood levels of haloperidol has been observed in patients receiving concomitant fluoxetine.

Phenytoin — Patients on stable doses of phenytoin have developed elevated plasma levels of phenytoin with clinical phenytoin toxicity following initiation of concomitant fluoxetine.

Drugs Metabolized by CYP2D6 — In vitro studies utilizing human liver microsomes suggest that olanzapine has little potential to inhibit CYP2D6. Thus, olanzapine is unlikely to cause clinically important drug interactions mediated by this enzyme.

Fluoxetine inhibits the activity of CYP2D6 and may make individuals with normal CYP2D6 metabolic activity resemble a poor metabolizer. Coadministration of fluoxetine with other drugs that are metabolized by CYP2D6, including certain antidepressants (e.g., TCAs), antipsychotics (e.g., phenothiazines and most atypicals), and antiarrhythmics (e.g., propafenone, flecainide, and others) should be approached with caution. Therapy with medications that are predominantly metabolized by the CYP2D6 system and that have a relatively narrow therapeutic index should be initiated at the low end of the dose range if a patient is receiving fluoxetine concurrently or has taken it in the previous 5 weeks. If fluoxetine is added to the treatment regimen of a patient already receiving a drug metabolized by CYP2D6, the need for a decreased dose of the original medication should be considered. Drugs with a narrow therapeutic index represent the greatest concern (including but not limited to, flecainide, propafenone, vinblastine, and TCAs).

Drugs Metabolized by CYP3A — In vitro studies utilizing human liver microsomes suggest that olanzapine has little potential to inhibit CYP3A. Thus, olanzapine is unlikely to cause clinically important drug interactions mediated by these enzymes.

In an in vivo interaction study involving the coadministration of fluoxetine with single doses of terfenadine (a CYP3A substrate), no increase in plasma terfenadine concentrations occurred with concomitant fluoxetine. In addition, in vitro studies have shown ketoconazole, a potent inhibitor of CYP3A activity, to be at least 100 times more potent than fluoxetine or norfluoxetine as an inhibitor of the metabolism of several substrates for this enzyme, including astemizole, cisapride, and midazolam. These data indicate that fluoxetine's extent of inhibition of CYP3A activity is not likely to be of clinical significance.

Effect of Olanzapine on Drugs Metabolized by Other CYP Enzymes — In vitro studies utilizing human liver microsomes suggest that olanzapine has little potential to inhibit CYP1A2, CYP2C9, and CYP2C19. Thus, olanzapine is unlikely to cause clinically important drug interactions mediated by these enzymes.

Lithium — Multiple doses of olanzapine did not influence the pharmacokinetics of lithium.

There have been reports of both increased and decreased lithium levels when lithium was used concomitantly with fluoxetine. Cases of lithium toxicity and increased serotonergic effects have been reported. Lithium levels should be monitored in patients taking SYMBYAX concomitantly with lithium [see Warnings and Precautions (5.5)].

Drugs Tightly Bound to Plasma Proteins — The in vitro binding of SYMBYAX to human plasma proteins is similar to the individual components. The interaction between SYMBYAX and other highly protein-bound drugs has not been fully evaluated. Because fluoxetine is tightly bound to plasma protein, the administration of fluoxetine to a patient taking another drug that is tightly bound to protein (e.g., Coumadin, digitoxin) may cause a shift in plasma concentrations potentially resulting in an adverse effect. Conversely, adverse effects may result from displacement of protein-bound fluoxetine by other tightly bound drugs [see Clinical Pharmacology (12.3)].

Valproate — In vitro studies using human liver microsomes determined that olanzapine has little potential to inhibit the major metabolic pathway, glucuronidation, of valproate. Further, valproate has little effect on the metabolism of olanzapine in vitro. Thus, a clinically significant pharmacokinetic interaction between olanzapine and valproate is unlikely.

Biperiden — Multiple doses of olanzapine did not influence the pharmacokinetics of biperiden.

Theophylline — Multiple doses of olanzapine did not affect the pharmacokinetics of theophylline or its metabolites.

Pregnancy Exposure Registry

There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to psychiatric medications, including SYMBYAX, during pregnancy. Healthcare providers are encouraged to register patients by contacting the National Pregnancy Registry for Psychiatric Medications at 1-866-961-2388 or https://womensmentalhealth.org/clinical-and-research-programs/pregnancyregistry/.

Risk Summary

Based on data from published observational studies, exposure to SSRIs, particularly in the month before delivery, has been associated with a less than 2-fold increase in the risk of postpartum hemorrhage [see Warnings and Precautions (5.16) and Clinical Considerations].

Neonates exposed to antipsychotic drugs, including the olanzapine component of SYMBYAX, during the third trimester are at risk for extrapyramidal and/or withdrawal symptoms following delivery (see Clinical Considerations).Overall available data from published epidemiologic studies and postmarketing reports of pregnant women exposed to olanzapine or fluoxetine have not established a drug-associated increased risk of major birth defects or miscarriage (see Data). Some studies in pregnant women exposed to fluoxetine have reported an increased incidence of cardiovascular malformations; however, these studies results do not establish a causal relationship (see Data). There are risks associated with untreated depression in pregnancy and risks of persistent pulmonary hypertension (PPHN) (see Data) and poor neonatal adaptation with exposure to selective serotonin reuptake inhibitors (SSRIs), including fluoxetine, during pregnancy (see Clinical Considerations). Neonates exposed to antipsychotic drugs, including the olanzapine component of SYMBYAX, during the third trimester are at risk for extrapyramidal and/or withdrawal symptoms following delivery (see Clinical Considerations).

In animal studies, administration of the combination of olanzapine and fluoxetine during the period of organogenesis resulted in adverse effects on development (decreased fetal body weights in rats and rabbits and retarded skeletal ossification in rabbits) at maternally toxic doses greater than those used clinically. When administered to rats throughout pregnancy and lactation, an increase in early postnatal mortality was observed at doses similar to those used clinically (see Data).

The estimated background risk of major birth defects and miscarriage for the indicated populations is unknown. All pregnancies have a background risk of birth defects, miscarriage, or another adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.

Clinical Considerations

Data

Risk Summary

Data from published literature report the presence of olanzapine, fluoxetine, and norfluoxetine in human milk (see Data). There are reports of excess sedation, irritability, poor feeding and extrapyramidal symptoms (tremors and abnormal muscle movements) in infants exposed to olanzapine through breast milk and reports of agitation, irritability, poor feeding and poor weight gain in infants exposed to fluoxetine through breast milk (see Clinical Considerations). There is no information on the effects of olanzapine or fluoxetine and their metabolites on milk production.

The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for SYMBYAX and any potential adverse effects on the breastfed child from SYMBYAX or the underlying maternal condition.

Clinical Considerations

Infants exposed to SYMBYAX should be monitored for agitation, irritability, poor feeding, poor weight gain, excess sedation, and extrapyramidal symptoms (tremors and abnormal muscle movements).

Data

A study of nineteen nursing mothers on fluoxetine with daily doses of 10-60 mg showed that fluoxetine was detectable in 30% of nursing infant sera (range: 1 to 84 ng/mL), whereas norfluoxetine was found in 85% (range: <1 to 265 ng/mL).

Infertility

Females

Based on the pharmacologic action of olanzapine (dopamine D₂ receptor blockade), treatment with SYMBYAX may result in an increase in serum prolactin levels, which may lead to a reversible reduction in fertility in females of reproductive potential [see Warnings and Precautions (5.22)].

SYMBYAX — The safety and efficacy of SYMBYAX in patients 10 to 17 years of age has been established for the acute treatment of Depressive Episodes Associated with Bipolar I Disorder in a single 8-week randomized, placebo-controlled clinical trial (N = 255) [see Clinical Studies (14.1)]. Patients were initiated at a dose of 3/25 mg/day and force-titrated to the maximum dose of 12/50 mg/day over two weeks. After Week 2, there was flexible dosing of SYMBYAX in the range of 6/25, 6/50, or 12/50 mg/day. The average dose was olanzapine 7.7 mg and fluoxetine 37.6 mg. The recommended starting dose for children and adolescents is 3/25 mg per day (lower than that for adults). Flexible dosing is recommended, rather than the forced titration used in the study [see Dosage and Administration (2.1)].

The types of adverse events observed with SYMBYAX in children and adolescents were generally similar to those observed in adults. However, the magnitude and frequency of some changes were greater in children and adolescents than adults. These included increases in lipids, hepatic enzymes, and prolactin, as well as increases in the QT interval [see Warnings and Precautions (5.5, 5.20, 5.22), and Vital Signs and Laboratory Studies (6.1)]. The frequency of weight gain ≥7%, and the magnitude and frequency of increases in lipids, hepatic analytes, and prolactin in children and adolescents treated with SYMBYAX were similar to those observed in adolescents treated with olanzapine monotherapy.

The safety and efficacy of olanzapine and fluoxetine in combination for the treatment of bipolar I depression in patients under the age of 10 years have not been established. The safety and effectiveness of olanzapine and fluoxetine in combination for treatment resistant depression in patients less than 18 years of age have not been established.

Anyone considering the use of SYMBYAX in a child or adolescent must balance the potential risks with the clinical need [see Boxed Warning and Warnings and Precautions (5.1)].

Olanzapine — Safety and effectiveness of olanzapine in children <13 years of age have not been established.

Compared to patients from adult clinical trials, adolescents treated with oral olanzapine were likely to gain more weight, experience increased sedation, and have greater increases in total cholesterol, triglycerides, LDL cholesterol, prolactin and hepatic aminotransferase levels.

Juvenile Animal Toxicity Data

Fluoxetine — Juvenile animal toxicity studies were performed for fluoxetine alone. Significant toxicity on muscle tissue, neurobehavior, reproductive organs, and bone development has been observed following exposure of juvenile rats to fluoxetine from weaning through maturity. Oral administration of fluoxetine to rats from weaning postnatal day 21 through adulthood day 90 at 3, 10, or 30 mg/kg/day was associated with testicular degeneration and necrosis, epididymal vacuolation and hypospermia (at 30 mg/kg/day corresponding to plasma exposures [AUC] approximately 5-10 times the average AUC in pediatric patients at the MRHD of 20 mg/day), increased serum levels of creatine kinase (at AUC as low as 1-2 times the average AUC in pediatric patients at the MRHD of 20 mg/day), skeletal muscle degeneration and necrosis, decreased femur length/growth and body weight gain (at AUC 5-10 times the average AUC in pediatric patients at the MRHD of 20 mg/day). The high dose of 30 mg/kg/day exceeded a maximum tolerated dose. When animals were evaluated after a drug-free period (up to 11 weeks after cessation of dosing), fluoxetine was associated with neurobehavioral abnormalities (decreased reactivity at AUC as low as approximately 0.1-0.2 times the average AUC in pediatric patients at the MRHD and learning deficit at the high dose), and reproductive functional impairment (decreased mating at all doses and impaired fertility at the high dose). In addition, the testicular and epididymal microscopic lesions and decreased sperm concentrations found in high dose group were also observed, indicating that the drug effects on reproductive organs are irreversible. The reversibility of fluoxetine-induced muscle damage was not assessed.

These fluoxetine toxicities in juvenile rats have not been observed in adult animals. Plasma exposures (AUC) to fluoxetine in juvenile rats receiving 3, 10, or 30 mg/kg/day doses in this study are approximately 0.1-0.2, 1-2, and 5-10 times, respectively, the average exposure in pediatric patients receiving the MRHD of 20 mg/day. Rat exposures to the major metabolite, norfluoxetine, are approximately 0.3-0.8, 1-8, and 3-20 times, respectively, the pediatric exposure at the MRHD.

A specific effect on bone development was reported in juvenile mice administered fluoxetine by the intraperitoneal route to 4 week old mice for 4 weeks at doses 0.5 and 2 times the oral MRHD of 20 mg/day on mg/m² basis. There was a decrease in bone mineralization and density at both doses, but the overall growth (body weight gain or femur length) was not affected.

SYMBYAX — Clinical studies of SYMBYAX did not include sufficient numbers of patients ≥65 years of age to determine whether they respond differently from younger patients. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy [see Dosage and Administration (2.3)].

Olanzapine — Of the 2500 patients in premarketing clinical studies with olanzapine, 11% (263 patients) were ≥65 years of age. In patients with Schizophrenia, there was no indication of any different tolerability of olanzapine in the elderly compared with younger patients. Studies in elderly patients with dementia-related psychosis have suggested that there may be a different tolerability profile in this population compared with younger patients with Schizophrenia. In placebo-controlled studies of olanzapine in elderly patients with dementia-related psychosis, there was a higher incidence of cerebrovascular adverse reactions (e.g., stroke, transient ischemic attack) in patients treated with olanzapine compared to patients treated with placebo. In 5 placebo-controlled studies of olanzapine in elderly patients with dementia-related psychosis (n=1184), the following adverse reactions were reported in olanzapine-treated patients at an incidence of at least 2% and significantly greater than placebo-treated patients: falls, somnolence, peripheral edema, abnormal gait, urinary incontinence, lethargy, increased weight, asthenia, pyrexia, pneumonia, dry mouth, and visual hallucinations. The rate of discontinuation due to adverse reactions was significantly greater with olanzapine than placebo (13% vs 7%). Elderly patients with dementia-related psychosis treated with olanzapine are at an increased risk of death compared to placebo. Olanzapine is not approved for the treatment of patients with dementia-related psychosis [see Boxed Warning and Warnings and Precautions (5.2)]

Also, the presence of factors that might decrease pharmacokinetic clearance or increase the pharmacodynamic response to olanzapine should lead to consideration of a lower starting dose for any geriatric patient.

Fluoxetine — US fluoxetine clinical studies included 687 patients ≥65 years of age and 93 patients ≥75 years of age. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out. SNRIs and SSRIs, including SYMBYAX, have been associated with cases of clinically significant hyponatremia in elderly patients, who may be at greater risk for this adverse reaction [see Warnings and Precautions (5.17)].

SYMBYAX — Fluoxetine (administered as a 60 mg single dose or 60 mg daily for 8 days) caused a small increase in the mean maximum concentration of olanzapine (16%) following a 5 mg dose, an increase in the mean area under the curve (17%) and a small decrease in mean apparent clearance of olanzapine (16%). In another study, a similar decrease in apparent clearance of olanzapine of 14% was observed following olanzapine doses of 6 or 12 mg with concomitant fluoxetine doses of 25 mg or more. The decrease in clearance reflects an increase in bioavailability. The terminal half-life is not affected, and therefore the time to reach steady state should not be altered. The overall steady-state plasma concentrations of olanzapine and fluoxetine when given as the combination in the therapeutic dose ranges were comparable with those typically attained with each of the monotherapies. The small change in olanzapine clearance, observed in both studies, likely reflects the inhibition of a minor metabolic pathway for olanzapine via CYP2D6 by fluoxetine, a potent CYP2D6 inhibitor, and was not deemed clinically significant. Therefore, the pharmacokinetics of the individual components is expected to reasonably characterize the overall pharmacokinetics of the combination.

Absorption and Bioavailability

SYMBYAX — Following a single oral 12 mg/50 mg dose of SYMBYAX, peak plasma concentrations of olanzapine and fluoxetine occur at approximately 4 and 6 hours, respectively. The effect of food on the absorption and bioavailability of SYMBYAX has not been evaluated. The bioavailability of olanzapine given as Zyprexa, and the bioavailability of fluoxetine given as Prozac were not affected by food. It is unlikely that there would be a significant food effect on the bioavailability of SYMBYAX.

Olanzapine — Olanzapine is well absorbed and reaches peak concentration approximately 6 hours following an oral dose. Food does not affect the rate or extent of olanzapine absorption when olanzapine is given as Zyprexa. It is eliminated extensively by first pass metabolism, with approximately 40% of the dose metabolized before reaching the systemic circulation.

Fluoxetine — Following a single oral 40 mg dose, peak plasma concentrations of fluoxetine from 15 to 55 ng/mL are observed after 6 to 8 hours. Food does not appear to affect the systemic bioavailability of fluoxetine given as Prozac, although it may delay its absorption by 1 to 2 hours, which is probably not clinically significant.

Distribution

SYMBYAX — The in vitro binding to human plasma proteins of olanzapine and fluoxetine in combination is similar to the binding of the individual components.

Olanzapine — Olanzapine is extensively distributed throughout the body, with a volume of distribution of approximately 1000 L. It is 93% bound to plasma proteins over the concentration range of 7 to 1100 ng/mL, binding primarily to albumin and α₁-acid glycoprotein.

Fluoxetine — Over the concentration range from 200 to 1000 ng/mL, approximately 94.5% of fluoxetine is bound in vitro to human serum proteins, including albumin and α₁-glycoprotein. The interaction between fluoxetine and other highly protein-bound drugs has not been fully evaluated [see Drug Interactions (7.7)].

Metabolism and Elimination

SYMBYAX — SYMBYAX therapy yielded steady-state concentrations of norfluoxetine similar to those seen with fluoxetine in the therapeutic dose range.

Olanzapine — Olanzapine displays linear pharmacokinetics over the clinical dosing range. Its half-life ranges from 21 to 54 hours (5th to 95th percentile; mean of 30 hr), and apparent plasma clearance ranges from 12 to 47 L/hr (5th to 95th percentile; mean of 25 L/hr). Administration of olanzapine once daily leads to steady-state concentrations in about 1 week that are approximately twice the concentrations after single doses. Plasma concentrations, half-life, and clearance of olanzapine may vary between individuals on the basis of smoking status, gender, and age [see Dosage and Administration (2.3) and Clinical Pharmacology (12.4)].

Following a single oral dose of ¹⁴C-labeled olanzapine, 7% of the dose of olanzapine was recovered in the urine as unchanged drug, indicating that olanzapine is highly metabolized. Approximately 57% and 30% of the dose was recovered in the urine and feces, respectively. In the plasma, olanzapine accounted for only 12% of the AUC for total radioactivity, indicating significant exposure to metabolites. After multiple dosing, the major circulating metabolites were the 10-N-glucuronide, present at steady state at 44% of the concentration of olanzapine, and 4′-N-desmethyl olanzapine, present at steady state at 31% of the concentration of olanzapine. Both metabolites lack pharmacological activity at the concentrations observed.

Direct glucuronidation and CYP450-mediated oxidation are the primary metabolic pathways for olanzapine. In vitro studies suggest that CYP1A2, CYP2D6, and the flavin-containing monooxygenase system are involved in olanzapine oxidation. CYP2D6-mediated oxidation appears to be a minor metabolic pathway in vivo, because the clearance of olanzapine is not reduced in subjects who are deficient in this enzyme.

Fluoxetine — Fluoxetine is a racemic mixture (50/50) of R-fluoxetine and S-fluoxetine enantiomers. In animal models, both enantiomers are specific and potent serotonin uptake inhibitors with essentially equivalent pharmacologic activity. The S-fluoxetine enantiomer is eliminated more slowly and is the predominant enantiomer present in plasma at steady state.

Fluoxetine is extensively metabolized in the liver to its only identified active metabolite, norfluoxetine, via the CYP2D6 pathway. A number of unidentified metabolites exist.

In animal models, S-norfluoxetine is a potent and selective inhibitor of serotonin uptake and has activity essentially equivalent to R- or S-fluoxetine. R-norfluoxetine is significantly less potent than the parent drug in the inhibition of serotonin uptake. The primary route of elimination appears to be hepatic metabolism to inactive metabolites excreted by the kidney.

Clinical Issues Related to Metabolism and Elimination

The complexity of the metabolism of fluoxetine has several consequences that may potentially affect the clinical use of SYMBYAX.

Variability in Metabolism — A subset (about 7%) of the population has reduced activity of the drug metabolizing enzyme CYP2D6. Such individuals are referred to as “poor metabolizers” of drugs such as debrisoquin, dextromethorphan, and the tricyclic antidepressants (TCAs). In a study involving labeled and unlabeled enantiomers administered as a racemate, these individuals metabolized S-fluoxetine at a slower rate and thus achieved higher concentrations of S-fluoxetine. Consequently, concentrations of S-norfluoxetine at steady state were lower. The metabolism of R-fluoxetine in these poor metabolizers appears normal. When compared with normal metabolizers, the total sum at steady state of the plasma concentrations of the 4 enantiomers was not significantly greater among poor metabolizers. Thus, the net pharmacodynamic activities were essentially the same. Alternative nonsaturable pathways (non-CYP2D6) also contribute to the metabolism of fluoxetine. This explains how fluoxetine achieves a steady-state concentration rather than increasing without limit.

Because the metabolism of fluoxetine, like that of a number of other compounds including TCAs and other selective serotonin antidepressants, involves the CYP2D6 system, concomitant therapy with drugs also metabolized by this enzyme system (such as the TCAs) may lead to drug interactions [see Drug Interactions (7.7)].

Accumulation and Slow Elimination — The relatively slow elimination of fluoxetine (elimination half-life of 1 to 3 days after acute administration and 4 to 6 days after chronic administration) and its active metabolite, norfluoxetine (elimination half-life of 4 to 16 days after acute and chronic administration), leads to significant accumulation of these active species in chronic use and delayed attainment of steady state, even when a fixed dose is used. After 30 days of dosing at 40 mg/day, plasma concentrations of fluoxetine in the range of 91 to 302 ng/mL and norfluoxetine in the range of 72 to 258 ng/mL have been observed. Plasma concentrations of fluoxetine were higher than those predicted by single-dose studies, because the metabolism of fluoxetine is not proportional to dose. However, norfluoxetine appears to have linear pharmacokinetics. Its mean terminal half-life after a single dose was 8.6 days and after multiple dosing was 9.3 days. Steady-state levels after prolonged dosing are similar to levels seen at 4 to 5 weeks.

The long elimination half-lives of fluoxetine and norfluoxetine assure that, even when dosing is stopped, active drug substance will persist in the body for weeks (primarily depending on individual patient characteristics, previous dosing regimen, and length of previous therapy at discontinuation). This is of potential consequence when drug discontinuation is required or when drugs are prescribed that might interact with fluoxetine and norfluoxetine following the discontinuation of fluoxetine.

Geriatric — Based on the individual pharmacokinetic profiles of olanzapine and fluoxetine, the pharmacokinetics of SYMBYAX may be altered in geriatric patients. Caution should be used in dosing the elderly, especially if there are other factors that might additively influence drug metabolism and/or pharmacodynamic sensitivity.

In a study involving 24 healthy subjects, the mean elimination half-life of olanzapine was about 1.5 times greater in elderly subjects (≥65 years of age) than in non-elderly subjects (<65 years of age).

The disposition of single doses of fluoxetine in healthy elderly subjects (≥65 years of age) did not differ significantly from that in younger normal subjects. However, given the long half-life and nonlinear disposition of the drug, a single-dose study is not adequate to rule out the possibility of altered pharmacokinetics in the elderly, particularly if they have systemic illness or are receiving multiple drugs for concomitant diseases. The effects of age upon the metabolism of fluoxetine have been investigated in 260 elderly but otherwise healthy depressed patients (≥60 years of age) who received 20 mg fluoxetine for 6 weeks. Combined fluoxetine plus norfluoxetine plasma concentrations were 209.3 ± 85.7 ng/mL at the end of 6 weeks. No unusual age-associated pattern of adverse reactions was observed in those elderly patients.

Renal Impairment — The pharmacokinetics of SYMBYAX has not been studied in patients with renal impairment. However, olanzapine and fluoxetine individual pharmacokinetics do not differ significantly in patients with renal impairment. SYMBYAX dosing adjustment based upon renal impairment is not routinely required.

Because olanzapine is highly metabolized before excretion and only 7% of the drug is excreted unchanged, renal dysfunction alone is unlikely to have a major impact on the pharmacokinetics of olanzapine. The pharmacokinetic characteristics of olanzapine were similar in patients with severe renal impairment and normal subjects, indicating that dosage adjustment based upon the degree of renal impairment is not required. In addition, olanzapine is not removed by dialysis. The effect of renal impairment on olanzapine metabolite elimination has not been studied.

In depressed patients on dialysis (N=12), fluoxetine administered as 20 mg once daily for 2 months produced steady-state fluoxetine and norfluoxetine plasma concentrations comparable with those seen in patients with normal renal function. While the possibility exists that renally excreted metabolites of fluoxetine may accumulate to higher levels in patients with severe renal dysfunction, use of a lower or less frequent dose is not routinely necessary in renally impaired patients.

Hepatic Impairment — Based on the individual pharmacokinetic profiles of olanzapine and fluoxetine, the pharmacokinetics of SYMBYAX may be altered in patients with hepatic impairment. The lowest starting dose should be considered for patients with hepatic impairment [see Dosage and Administration (2.3) and Warnings and Precautions (5.20)].

Although the presence of hepatic impairment may be expected to reduce the clearance of olanzapine, a study of the effect of impaired liver function in subjects (N=6) with clinically significant cirrhosis (Child-Pugh Classification A and B) revealed little effect on the pharmacokinetics of olanzapine.

As might be predicted from its primary site of metabolism, liver impairment can affect the elimination of fluoxetine. The elimination half-life of fluoxetine was prolonged in a study of cirrhotic patients, with a mean of 7.6 days compared with the range of 2 to 3 days seen in subjects without liver disease; norfluoxetine elimination was also delayed, with a mean duration of 12 days for cirrhotic patients compared with the range of 7 to 9 days in normal subjects.

Gender — Clearance of olanzapine is approximately 30% lower in women than in men. There were, however, no apparent differences between men and women in effectiveness or adverse effects. Dosage modifications based on gender should not be needed.

Smoking Status — Olanzapine clearance is about 40% higher in smokers than in nonsmokers, although dosage modifications are not routinely required.

Race — No SYMBYAX pharmacokinetic study was conducted to investigate the effects of race. In vivo studies have shown that exposures to olanzapine are similar among Japanese, Chinese and Caucasians, especially after normalization for body weight differences. Dosage modifications for race, therefore, are not routinely required.

Combined Effects — The combined effects of age, smoking, and gender could lead to substantial pharmacokinetic differences in populations. The clearance of olanzapine in young smoking males, for example, may be 3 times higher than that in elderly nonsmoking females. SYMBYAX dosing modification may be necessary in patients who exhibit a combination of factors that may result in slower metabolism of the olanzapine component [see Dosage and Administration (2.3)].

Children and Adolescents (ages 10 to 17 years)— Based on the pediatric SYMBYAX study, steady-state olanzapine, fluoxetine, and norfluoxetine plasma concentrations were about 31%, 76%, and 38% higher, respectively, in pediatric patients with lower body weights (less than 50 kg) than in pediatric patients with high body weight (greater than or equal to 50 kg). Exposures in pediatric patients with high body weight were similar to those previously observed in adults. Dose modifications based on body weight are not required.

Carcinogenesis

Impairment of Fertility