Drug Interaction Report

MONITOR: Coadministration with inhibitors of CYP450 1A2 and/or 3A4 may increase the plasma concentrations of levobupivacaine, which is primarily metabolized by these isoenzymes. Although no clinical studies have been conducted, the possibility of prolonged and/or increased pharmacologic effects of levobupivacaine should be considered.

MANAGEMENT: Caution may be advisable if levobupivacaine is administered to patients receiving inhibitors of CYP450 1A2 (e.g., quinolones, deferasirox, mexiletine, propafenone, ticlopidine, zileuton) or CYP450 3A4 (e.g., azole antifungals, macrolide antibiotics, protease inhibitors, kinase inhibitors, aprepitant, conivaptan, cyclosporine, delavirdine, diltiazem, nefazodone, verapamil). Particular caution and dosage adjustment of levobupivacaine may be warranted during concomitant use of both a CYP450 1A2 inhibitor and a CYP450 3A4 inhibitor, or a drug that inhibits both isoenzymes (e.g., fluvoxamine). Patients should be monitored for early signs and symptoms of central nervous system toxicity such as dizziness, drowsiness, lightheadedness, anxiety, restlessness, incoherent speech, tremors, twitching, numbness and tingling of the mouth and lips, metallic taste, tinnitus, and blurred vision, as well as more serious reactions including convulsions, hypotension, arrhythmias, and cardiorespiratory depression.

GENERALLY AVOID: Taking stiripentol on an empty stomach may reduce its oral bioavailability. Stiripentol degrades rapidly when exposed to gastric acid in an empty stomach.

GENERALLY AVOID: Alcohol may potentiate the depressant effects of stiripentol on the central nervous system. Concomitant use may result in increased sedation and dizziness as well as impairment of psychomotor skills.

GENERALLY AVOID: It is not known whether stiripentol may reduce theophylline and caffeine metabolism, as data on the potential for inhibition of CYP450 1A2 are limited. Consumption of foods and nutritional products such as cola drinks (which contain significant quantities of caffeine) and chocolate (which contains caffeine and trace amounts of theophylline) may be unsafe during treatment with stiripentol, particularly in children.

MANAGEMENT: Stiripentol should be taken during a meal for optimal absorption; however, it should not be taken with milk, dairy products (e.g., yogurt, soft cream cheese), fruit juice, or carbonated beverages. Patients should be advised to avoid or limit consumption of alcohol and to avoid activities requiring mental alertness such as driving or operating hazardous machinery until they know how the medication affects them. Food and beverages that may contain caffeine or theophylline such as colas, chocolate, coffee, tea, or energy drinks should also be avoided during treatment with stiripentol.