Tasimelteon

Potential effect of alcohol on tasimelteon

In a study of 28 healthy volunteers, a single dose of ethanol (0.6 g/kg for women and 0.7 g/kg for men) was co-administered with a 20 mg dose of tasimelteon. On some psychomotor test measures (intoxication, drunk, alertness/drowsiness, balance platform test), there was a trend towards greater effects of tasimelteon plus ethanol versus ethanol alone, but the effects were not deemed significant.

Tasimelteon exposure was increased by approximately 50% when co-administered with ketoconazole 400 mg (after 5 days of ketoconazole 400 mg per day). The clinical relevance of this single factor is unclear, but with increased exposure caution is recommended to monitor the patient.

Use of tasimelteon should be avoided in combination with rifampin or other CYP3A4 inducers because of a potentially large decrease in tasimelteon exposure with reduced efficacy: the exposure of tasimelteon decreased by approximately 90% when co-administered with rifampin 600 mg (after 11 days of rifampin 600 mg per day).

Caution should be used when administering tasimelteon in combination with fluvoxamine or other strong CYP1A2 inhibitors such as ciprofloxacin and enoxacin because of a potentially large increase in tasimelteon exposure and greater risk of adverse reactions: the AUC_0-inf and C_max of tasimelteon increased by 7-fold and 2-fold, respectively, when co-administered with fluvoxamine 50 mg (after 6 days of fluvoxamine 50 mg per day). This is deemed even more important for strong CYP1A2 inhibitors also inhibiting other enzymes involved in the clearance of tasimelteon (e.g. fluvoxamine and ciprofloxacin).

Tasimelteon has not been studied in patients with severe hepatic impairment (Child-Pugh Class C); therefore caution is recommended when prescribing tasimelteon to patients with severe hepatic impairment.

The efficacy of tasimelteon may be reduced in patients with concomitant administration of beta adrenergic receptor antagonists. Monitoring of efficacy is recommended where if efficacy is not achieved by a patient on beta blocker medication, the physician may consider whether a substitution of another non-beta-blocker medication for the beta blocker is warranted or discontinue the use of tasimelteon.

Tasimelteon exposure decreased by approximately 40% in smokers compared to non-smokers. The patient should be instructed to cease or reduce smoking while taking tasimelteon.

There are no or limited amount of data from the use of tasimelteon in pregnant women. In animal studies, administration of tasimelteon during pregnancy resulted in developmental toxicity (embryofoetal mortality, neurobehavioural impairment, and decreased growth and development in offspring) at doses greater than those used clinically. As a precautionary measure, it is preferable to avoid the use of tasimelteon during pregnancy.

It is unknown whether tasimelteon/metabolites are excreted in human milk. A risk to the breast-fed child cannot be excluded. A decision must be made whether to discontinue breast-feeding or to discontinue/abstain from tasimelteon therapy taking into account the benefit of breast-feeding for the child and the benefit of therapy for the woman.

Fertility

There are no data on the effects of tasimelteon on human fertility. Reproductive and developmental toxicity studies showed that oestrous cycles were prolonged in rats treated with high doses of tasimelteon, with no effect on mating performance or male fertility, and only a marginal effect on female fertility.

Tasimelteon may cause somnolence, and therefore may have an influence on driving and using machines. After taking tasimelteon, patients should limit their activity to preparing to go to bed and not use machines because tasimelteon can impair performance of activities requiring complete mental alertness.

Summary of the safety profile

The most common adverse reactions (>3%) during clinical trials were headache (10.4%), somnolence (8.6%), nausea (4.0%), and dizziness (3.1%). The most frequently reported adverse reactions were mostly mild to moderate in severity and transient in nature.

Adverse reactions leading to discontinuation occurred in 2.3% of tasimelteon-treated patients. The most frequent adverse reactions leading to discontinuation were: somnolence (0.23%), nightmare (0.23%), and headache (0.17%).

Tabulated list of adverse reactions

The following are adverse reactions that were reported in tasimelteon-treated adult patients, derived from patient trials in 1772 patients treated with tasimelteon. The following terms and frequencies are applied and presented by MedDRA System Organ Class: Very common (≥1/10); Common (≥1/100 to <1/10); Uncommon (≥1/1,000 to <1/100); Rare (≥1/10,000 to <1/1,000); Very rare (<1/10,000). Within each frequency grouping, adverse reactions are presented in order of decreasing seriousness.

Summary of Adverse Drug Reactions: