Drug Interactions between efavirenz and fidanacogene elaparvovec

ADJUST DOSING INTERVAL: Administration with food increases the plasma concentrations of efavirenz and may increase the frequency of adverse reactions. According to the product labeling, administration of efavirenz capsules (600 mg single dose) with a high-fat/high-caloric meal (894 kcal, 54 g fat, 54% calories from fat) or a reduced-fat/normal-caloric meal (440 kcal, 2 g fat, 4% calories from fat) was associated with mean increases of 39% and 51% in efavirenz peak plasma concentration (Cmax) and 22% and 17% in systemic exposure (AUC), respectively, compared to administration under fasted conditions. For efavirenz tablets, administration of a single 600 mg dose with a high-fat/high-caloric meal (approximately 1000 kcal, 500-600 kcal from fat) resulted in a 79% increase in mean Cmax and a 28% increase in mean AUC of efavirenz relative to administration under fasted conditions.

GENERALLY AVOID: Alcohol may potentiate the central nervous system (CNS) depressant effects of efavirenz. Concomitant use may result in additive CNS depression and impairment of judgment, thinking, and psychomotor skills. In more severe cases, hypotension, respiratory depression, profound sedation, coma, or even death may occur.

MANAGEMENT: Efavirenz should be taken on an empty stomach, preferably at bedtime. Dosing at bedtime may improve the tolerability of nervous system symptoms such as dizziness, insomnia, impaired concentration, somnolence, abnormal dreams and hallucinations, although they often resolve on their own after the first 2 to 4 weeks of therapy . Patients should be advised of the potential for additive central nervous system effects when efavirenz is used concomitantly with alcohol or psychoactive drugs, and to avoid driving or operating hazardous machinery until they know how the medication affects them.

GENERALLY AVOID: Coadministration with other hepatotoxic agents such as alcohol may increase the risk of liver injury and decrease the therapeutic efficacy of liver-directed adeno-associated virus (AAV) vector fidanacogene elaparvovec, designed to help replace missing and coagulation factor IX. Increased transaminase levels from AAV therapy have been attributed to immune-mediated injury of transduced hepatocytes, which may decrease their therapeutic efficacy. In addition, alcohol may impact liver enzyme elevation as well as reduce the activity of coagulation factor IX. In a prospective, open-label, single-arm, multinational clinical study of adult male patients with moderately severe to severe hemophilia B (n=45) receiving a single dose of fidanacogene elaparvovec (5 x 10[11] vector genomes [vg]/kg), increased transaminase levels greater than or equal to 1.5 times baseline were reported in 29 patients. Of these patients, 28 received treatment with corticosteroids due to increased transaminases and/or a decline in factor IX activity, with a mean initiation time to corticosteroid therapy reported at 45 days.

MANAGEMENT: According to the manufacturer, for the first year after administration of fidanacogene elaparvovec, alcohol consumption should be limited.