Belsomra

Risk Summary

Available data from postmarketing reports with BELSOMRA use in pregnant women are insufficient to establish a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes.

In animal reproduction studies, oral administration of suvorexant to pregnant rats and rabbits during the period of organogenesis decreased maternal body weight and/or weight gain at doses ≥ 30 and 28 times the maximum recommended human dose (MRHD) of 20 mg based on AUC in the rat and rabbit, respectively. Suvorexant caused decreased fetal weight at doses ≥ 86 times the MRHD based on AUC in the rat and did not cause significant fetal toxicity at doses up to 28 times the MRHD based on AUC in the rabbit. The no observed adverse effect levels (NOAELs) for fetal toxicity are 25 and 28 times the MRHD based on AUC in the rat and rabbit, respectively. Oral administration of suvorexant to pregnant rats during pregnancy and lactation caused decreased maternal and pup body weight or weight gain at approximately 48 times the MRHD based on AUC. The NOAEL for development toxicity in the rat is 25 times the MRHD based on AUC (see Data).

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the US 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.

Data

Risk Summary

There are no data on the presence of suvorexant in human milk, the effects on the breastfed infant or the effects on milk production. Suvorexant and hydroxyl-suvorexant are present in rat milk. When a drug is present in animal milk, it is likely that the drug will be present in human milk. Infants exposed to BELSOMRA through breastmilk should be monitored for excessive sedation. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for BELSOMRA and any potential adverse effects on the breastfed infant from BELSOMRA or from the underlying maternal condition.

Obstructive Sleep Apnea

The respiratory depressant effect of BELSOMRA was evaluated after one night and after four consecutive nights of treatment in a randomized, placebo-controlled, 2-period crossover study in patients (n=26) with mild to moderate obstructive sleep apnea. Following once-daily doses of 40 mg, the mean Apnea/Hypopnea Index treatment difference (suvorexant – placebo) on Day 4 was 2.7 (90% CI: 0.22 to 5.09), but there was wide inter- and intra-individual variability such that clinically meaningful respiratory effects of BELSOMRA in obstructive sleep apnea cannot be excluded. BELSOMRA has not been studied in patients with severe obstructive sleep apnea [see Warnings and Precautions (5.5)].

Chronic Obstructive Pulmonary Disease

The respiratory depressant effect of BELSOMRA was evaluated after one night and after four consecutive nights of treatment in a randomized, placebo-controlled, 2-period crossover study in patients (n=25) with mild to moderate chronic obstructive pulmonary disease (COPD). BELSOMRA (40 mg in non-elderly, 30 mg in elderly) had no respiratory depressant effects in patients with mild to moderate COPD, as measured by oxygen saturation. There was wide inter- and intra-individual variability such that clinically meaningful respiratory effects of BELSOMRA in COPD cannot be excluded. BELSOMRA has not been studied in patients with severe COPD [see Warnings and Precautions (5.5)].

Adverse Reactions Resulting in Discontinuation of Treatment

The incidence of discontinuation due to adverse reactions for patients treated with 15 mg or 20 mg of BELSOMRA was 3% compared to 5% for placebo. No individual adverse reaction led to discontinuation at an incidence ≥1%.

Most Common Adverse Reactions

In clinical trials of patients with insomnia treated with BELSOMRA 15 mg or 20 mg, the most common adverse reaction (reported in 5% or more of patients treated with BELSOMRA and at least twice the placebo rate) was somnolence (BELSOMRA 7%; placebo 3%).

Table 2 shows the percentage of patients with adverse reactions during the first three months of treatment, based on the pooled data from 3-month controlled efficacy trials (Study 1 and Study 2).

At doses of 15 or 20 mg, the incidence of somnolence was higher in females (8%) than in males (3%). Of the adverse reactions reported in Table 2, the following occurred in women at an incidence of at least twice that in men: headache, abnormal dreams, dry mouth, cough, and upper respiratory tract infection.

The adverse reaction profile in elderly patients was generally consistent with non-elderly patients. The adverse reactions reported during long-term treatment up to 1 year were generally consistent with those observed during the first 3 months of treatment.

Dose Relationship for Adverse Reactions

There is evidence of a dose relationship for many of the adverse reactions associated with BELSOMRA use, particularly for certain CNS adverse reactions.

In a placebo-controlled crossover study (Study 3), non-elderly adult patients were treated for up to one month with BELSOMRA at doses of 10 mg, 20 mg, 40 mg (2 times the maximum recommended dose) or 80 mg (4 times the maximum recommended dose). In patients treated with BELSOMRA 10 mg (n=62), the types of adverse reactions observed were similar to those observed in patients treated with BELSOMRA 20 mg. BELSOMRA was associated with a dose-related increase in somnolence: 2% at the 10 mg dose, 5% at the 20 mg dose, 12% at the 40 mg dose, and 11% at the 80 mg dose, compared to <1% for placebo. BELSOMRA was also associated with a dose-related increase in serum cholesterol: 1 mg/dL at the 10 mg dose, 2 mg/dL at the 20 mg dose, 3 mg/dL at the 40 mg dose, and 6 mg/dL at the 80 mg dose after 4 weeks of treatment, compared to a 4 mg/dL decrease for placebo.

Insomnia Study in Patients with Mild to Moderate Alzheimer's Disease

In a 4-week insomnia study of BELSOMRA in 285 patients (BELSOMRA n=142; placebo n=143) with mild to moderate Alzheimer's Disease, the adverse reactions occurring ≥2% and greater than placebo were somnolence (4% compared to 1% for placebo), dry mouth (2% compared to 1% for placebo), and falls (2% compared to 0% for placebo) [see Clinical Studies (14.1)].

CYP3A Inhibitors

Concomitant use of BELSOMRA with strong inhibitors of CYP3A (e.g., ketoconazole, itraconazole, posaconazole, clarithromycin, nefazodone, ritonavir, saquinavir, nelfinavir, indinavir, boceprevir, telaprevir, telithromycin and conivaptan) is not recommended [see Clinical Pharmacology (12.3)].

The recommended dose of BELSOMRA is 5 mg in subjects receiving moderate CYP3A inhibitors (e.g., amprenavir, aprepitant, atazanavir, ciprofloxacin, diltiazem, erythromycin, fluconazole, fosamprenavir, grapefruit juice, imatinib, verapamil). The dose generally should not exceed 10 mg in patients receiving moderate CYP3A inhibitors [see Clinical Pharmacology (12.3)].

CYP3A Inducers

Suvorexant exposure can be substantially decreased when co-administered with strong CYP3A inducers (e.g., rifampin, carbamazepine and phenytoin). The efficacy of BELSOMRA may be reduced [see Clinical Pharmacology (12.3)].

Digoxin

Concomitant administration of BELSOMRA with digoxin slightly increased digoxin levels due to inhibition of intestinal P-gp. Digoxin concentrations should be monitored when co-administering BELSOMRA with digoxin [see Clinical Pharmacology (12.3)].

Evaluation of QTc Interval

The effects of suvorexant on the QTc interval were evaluated in a randomized, placebo-, and active-controlled (moxifloxacin 400 mg) crossover study in healthy subjects (n=53). The upper bound of the one-sided 95% confidence interval for the largest placebo-adjusted, baseline-corrected QTc interval was below 10 ms based on analysis of suvorexant doses up to 240 mg, 12 times the maximum recommended dose. BELSOMRA thus does not prolong the QTc interval to any clinically relevant extent.

Absorption

Suvorexant peak concentrations occur at a median Tmax of 2 hours (range 30 minutes to 6 hours) under fasted conditions. The mean absolute bioavailability of 10 mg is 82%.

Distribution

The mean volume of distribution of suvorexant is approximately 49 liters. Suvorexant is extensively bound (>99%) to human plasma proteins and does not preferentially distribute into red blood cells. Suvorexant binds to both human serum albumin and α1-acid glycoprotein.

Elimination

Specific Populations

Gender, age, body mass index (BMI), and race were included as factors assessed in the population pharmacokinetic model to evaluate suvorexant pharmacokinetics in healthy subjects and to predict exposures in the patient population. Age and race are not predicted to have any clinically meaningful changes on suvorexant pharmacokinetics; therefore, no dose adjustment is warranted based upon these factors.

Suvorexant exposure is higher in females than in males. In females, the AUC and Cmax are increased by 17% and 9%, respectively, following administration of BELSOMRA 40 mg. The average concentration of suvorexant 9 hours after dosing is 5% higher for females across the dose range studied (10-40 mg). Dose adjustment of BELSOMRA is generally not needed based on gender only.

Apparent oral clearance of suvorexant is inversely related to body mass index. In obese patients, the AUC and Cmax are increased by 31% and 17%, respectively. The average concentration of suvorexant approximately 9 hours after a 20 mg dose is 15% higher in obese patients (BMI > 30 kg/m2) relative to those with a normal BMI (BMI ≤ 25 kg/m2).

In obese females, the AUC and Cmax are increased by 46% and 25%, respectively, compared to non-obese females. The higher exposure to suvorexant in obese females should be considered before increasing dose [see Dosage and Administration (2.2)].

The effects of renal and hepatic impairment on the pharmacokinetics of suvorexant were evaluated in specific pharmacokinetic studies.

Suvorexant exposure after a single dose was similar in patients with moderate hepatic insufficiency (Child-Pugh category 7 to 9) and healthy matched control subjects; however, the suvorexant apparent terminal half-life was increased from approximately 15 hours (range 10 - 22 hours) in healthy subjects to approximately 19 hours (range 11 - 49 hours) in patients with moderate hepatic insufficiency [see Use in Specific Populations (8.7)].

Suvorexant exposure (expressed as total and unbound concentrations) was similar between patients with severe renal impairment (urinary creatinine clearance ≤30 mL/min/1.73m2) and healthy matched control subjects. No dose adjustment is required in patients with renal impairment [see Use in Specific Populations (8.8)].

Drug Interaction Studies

Carcinogenesis

Rats were orally administered suvorexant at doses of 80, 160, and 325 mg/kg/day [males] or 40, 80, and 325 mg/kg/day [females] for 2 years. Suvorexant increased the incidences of thyroid follicular cell adenoma and combined adenoma/carcinoma in females at 325 mg/kg/day, thyroid follicular cell adenoma in males at ≥ 160 mg/kg/day, and hepatocellular adenoma in males at 325 mg/kg/day. These findings were consistent with increased TSH and hepatic enzyme induction, respectively, which are mechanisms believed to be rodent-specific. Suvorexant did not increase the incidence of tumors in rats at 80 mg/kg/day, which is approximately 7 times the MRHD based on AUC.

Suvorexant did not increase the incidence of tumors in Tg.rasH2 mice treated for 26 weeks at oral doses of 25, 50, 200, and 650 mg/kg/day.

Mutagenesis

Suvorexant was not mutagenic in the in vitro bacterial reverse mutation (Ames) assay or clastogenic in the in vitro mammalian chromosomal aberration assay or in the in vivo mouse and rat bone marrow micronucleus assays.

Impairment of Fertility

In two separate studies, suvorexant was orally administered to male and female rats at doses of 80, 160, and 325 mg/kg/day or 100, 300, and 1200 mg/kg/day [males] and 30, 80, and 325 mg/kg/day or 25, 75, and 1200 mg/kg/day [females] prior to and throughout mating and continuing in females to gestation day 7. Increases in pre-implantation loss and resorption and decreases in live fetuses were observed at the highest doses of 325 or 1200 mg/kg/day, when treated males and females were mated with untreated animals. The NOAELs for fertility are 160 and 80 mg/kg/day in males and females, respectively, which are approximately 20 times the MRHD based on AUC.

Insomnia Study in Patients with Mild to Moderate Alzheimer's Disease

A randomized, double-blind, placebo-controlled, parallel-group, multi-site 4-week trial of BELSOMRA was conducted in patients with mild to moderate Alzheimer's disease (n=285) for the treatment of insomnia. Male and female subjects aged 50-90 years (inclusive) were treated with BELSOMRA (n=142) or placebo (n=143). Patients treated with BELSOMRA received 10 mg for approximately 14 days, of whom 77% were increased to 20 mg for approximately 14 additional days.

In this study, patients treated with BELSOMRA exhibited a statistically significant improvement for both Total Sleep Time (TST) and Wake After Sleep Onset (WASO) measures, compared to those treated with placebo, as assessed by polysomnography at Week 4.

Effects on Driving

Two randomized, double-blind, placebo- and active-controlled, four-period crossover studies evaluated the effects of nighttime administration of BELSOMRA on next-morning driving performance 9 hours after dosing in 24 healthy elderly subjects (≥65 years old, mean age 69 years; 14 men, 10 women) who received 15 mg and 30 mg BELSOMRA, and 28 non-elderly subjects (mean age 46 years; 13 men, 15 women) who received 20 mg and 40 mg BELSOMRA. Testing was conducted after one night and after 8 consecutive nights of treatment with BELSOMRA at these doses.

The primary outcome measure was change in Standard Deviation of Lane Position (SDLP), a measure of driving performance, assessed using a symmetry analysis. The analysis showed clinically meaningful impaired driving performance in some subjects. After one night of dosing, this effect was observed in non-elderly subjects after either a 20 mg or 40 mg dose of BELSOMRA. A statistically significant effect was not observed in elderly subjects after a 15 mg or 30 mg dose of BELSOMRA. Across these two studies, five subjects (4 non-elderly women on BELSOMRA; 1 elderly woman on placebo) prematurely stopped their driving tests due to somnolence. Patients using the 20 mg dose of BELSOMRA should be cautioned against next-day driving and other activities requiring full mental alertness. Patients taking lower doses of BELSOMRA should also be cautioned about the potential for driving impairment because there is individual variation in sensitivity to BELSOMRA [see Warnings and Precautions (5.1)].

Effects on Next-Day Memory and Balance in Elderly and Non-Elderly

Four placebo-controlled trials evaluated the effects of nighttime administration of BELSOMRA on next-day memory and balance using word learning tests and body sway tests, respectively. Three trials showed no significant effects on memory or balance compared to placebo. In a fourth trial in healthy non-elderly subjects, there was a significant decrease in word recall after the words were presented to subjects in the morning following a single dose of 40 mg BELSOMRA, and there was a significant increase on body sway area in the morning following a single dose of 20 mg or 40 mg BELSOMRA.

Middle of the Night Safety in Elderly Subjects

A double-blind, randomized, placebo-controlled trial evaluated the effect of a single dose of BELSOMRA on balance, memory and psychomotor performance in healthy elderly subjects (n=12) after being awakened during the night. Nighttime dosing of BELSOMRA 30 mg resulted in impairment of balance (measured by body sway area) at 90 minutes as compared to placebo. Memory was not impaired, as assessed by an immediate and delayed word recall test at 4 hours post-dose.

Rebound Effects

In 3-month controlled safety and efficacy trials (Study 1, Study 2), rebound insomnia was assessed following discontinuation of BELSOMRA relative to placebo and baseline in non-elderly adult patients receiving BELSOMRA 40 mg or 20 mg and in elderly patients receiving BELSOMRA 30 mg or 15 mg. No clear effects were observed on measures of sleep onset or maintenance.

Withdrawal Effects

In 3-month controlled safety and efficacy trials (Study 1, Study 2), withdrawal effects were assessed following discontinuation in non-elderly adult patients who received BELSOMRA 40 mg or 20 mg and elderly patients who received BELSOMRA 30 mg or 15 mg. The analysis showed no clear evidence of withdrawal in the overall study population based on assessment of patient responses to the Tyrer Withdrawal Symptom Questionnaire or assessment of withdrawal-related adverse events following the discontinuation of BELSOMRA.

Respiratory Safety