Effects of PROVIGIL on CYP3A4/5 Substrates
The clearance of drugs that are substrates for CYP3A4/5 (e.g., steroidal contraceptives, cyclosporine, midazolam, and triazolam) may be increased by PROVIGIL via induction of metabolic enzymes, which results in lower systemic exposure. Dosage adjustment of these drugs should be considered when these drugs are used concomitantly with PROVIGIL [see CLINICAL PHARMACOLOGY].
The effectiveness of steroidal contraceptives may be reduced when used with PROVIGIL and for one month after discontinuation of therapy. Alternative or concomitant methods of contraception are recommended for patients taking steroidal contraceptives (e.g., ethinyl estradiol) when treated concomitantly with PROVIGIL and for one month after discontinuation of PROVIGIL treatment.
Blood levels of cyclosporine may be reduced when used with PROVIGIL. Monitoring of circulating cyclosporine concentrations and appropriate dosage adjustment for cyclosporine should be considered when used concomitantly with PROVIGIL.
Effects of PROVIGIL on CYP2C19 Substrates
Elimination of drugs that are substrates for CYP2C19 (e.g., phenytoin, diazepam, propranolol, omeprazole, and clomipramine) may be prolonged by PROVIGIL via inhibition of metabolic enzymes, with resultant higher systemic exposure. In individuals deficient in the CYP2D6 enzyme, the levels of CYP2D6 substrates which have ancillary routes of elimination through CYP2C19, such as tricyclic antidepressants and selective serotoninreuptake inhibitors, may be increased by co-administration of PROVIGIL. Dose adjustments of these drugs and other drugs that are substrates for CYP2C19 may be necessary when used concomitantly with PROVIGIL [see CLINICAL PHARMACOLOGY].
More frequent monitoring of prothrombin times/INR should be considered whenever PROVIGIL is coadministered with warfarin [see CLINICAL PHARMACOLOGY].
Monoamine Oxidase (MAO) Inhibitors
Caution should be used when concomitantly administering MAO inhibitors and PROVIGIL.
Drug Abuse And Dependence
PROVIGIL contains modafinil, a Schedule IV controlled substance.
In humans, modafinil produces psychoactive and euphoric effects, alterations in mood, perception, thinking, and feelings typical of other CNS stimulants. In in vitro binding studies, modafinil binds to the dopamine reuptake site and causes an increase in extracellular dopamine, but no increase in dopamine release. Modafinil is reinforcing, as evidenced by its self-administration in monkeys previously trained to self-administer cocaine. In some studies, modafinil was also partially discriminated as stimulant-like. Physicians should follow patients closely, especially those with a history of drug and/or stimulant (e.g., methylphenidate, amphetamine, or cocaine) abuse. Patients should be observed for signs of misuse or abuse (e.g., incrementation of doses or drug-seeking behavior).
The abuse potential of modafinil (200, 400, and 800 mg) was assessed relative to methylphenidate (45 and 90 mg) in an inpatient study in individuals experienced with drugs of abuse. Results from this clinical study demonstrated that modafinil produced psychoactive and euphoric effects and feelings consistent with other scheduled CNS stimulants (methylphenidate).
In one placebo-controlled clinical trial, the effects of modafinil withdrawal were monitored following 9 weeks of modafinil use. There were no reported withdrawal symptoms with modafinil during 14 days of observation, although sleepiness returned in narcoleptic patients.