Clinical pharmacokinetic profile of modafinil.
Article Details
- CitationCopy to clipboard
Robertson P Jr, Hellriegel ET
Clinical pharmacokinetic profile of modafinil.
Clin Pharmacokinet. 2003;42(2):123-37.
- PubMed ID
- 12537513 [ View in PubMed]
- Abstract
Modafinil is a unique wake-promoting agent for oral administration. Its pharmacological properties are distinct from those of other CNS agents, and it selectively targets neuronal pathways in the sleep/wake centres of the brain. After single or multiple oral doses, modafinil is readily absorbed, reaching maximum plasma concentrations at 2-4 hours after administration and pharmacokinetic steady state within 2-4 days. Its pharmacokinetics are dose-independent between 200 and 600 mg/day. The elimination half-life is approximately 12-15 hours, which is largely reflective of the pharmacokinetics of the longer-lived l-enantiomer. Modafinil is primarily eliminated via metabolism, mainly in the liver, with subsequent excretion in the urine. Less than 10% of the dose is excreted as unchanged drug. Metabolism is largely via amide hydrolysis, with lesser contributions from cytochrome P450 (CYP)-mediated oxidative pathways. In patients who are renally or hepatically compromised, the elimination processes can be slowed, and in a similar manner (although to a lesser extent), elimination in the elderly may be reduced due to normal effects of aging. Because modafinil is administered concomitantly with other medications, the potential for metabolic drug-drug interactions has been examined both in vitro and in vivo. In vitro, modafinil was observed to produce a reversible inhibition of CYP2C19 in human liver microsomes. It also caused a small, but concentration-dependent, induction of CYP1A2, CYP2B6 and CYP3A4 activities and suppression of CYP2C9 activity in primary cultures of human hepatocytes. Clinical studies have been conducted to examine the potential for interactions with methylphenidate, dexamfetamine, warfarin, ethinylestradiol and triazolam. The only substantive interactions observed were with ethinylestradiol and triazolam, apparently through induction of CYP3A4, primarily in the gastrointestinal system. Overall, the results of the interaction studies suggest that modafinil has potential to affect the pharmacokinetics of drugs that are metabolised by certain CYP enzymes. Compounds that induce or inhibit CYP activity are unlikely to have major effects on the pharmacokinetics of modafinil. In summary, the results show that modafinil is a moderately long-lived drug that is well absorbed and extensively metabolised.
DrugBank Data that Cites this Article
- Drug Enzymes
Drug Enzyme Kind Organism Pharmacological Action Actions Armodafinil Cytochrome P450 1A2 Protein Humans UnknownInducerDetails Armodafinil Cytochrome P450 2B6 Protein Humans UnknownInducerDetails Armodafinil Cytochrome P450 2C19 Protein Humans UnknownInhibitorDetails Armodafinil Cytochrome P450 2C9 Protein Humans NoInhibitorDetails Armodafinil Cytochrome P450 3A4 Protein Humans UnknownInducerDetails Armodafinil Cytochrome P450 3A5 Protein Humans UnknownInducerDetails Modafinil Cytochrome P450 1A2 Protein Humans UnknownInducerDetails Modafinil Cytochrome P450 2B6 Protein Humans UnknownInhibitorInducerDetails Modafinil Cytochrome P450 2C19 Protein Humans UnknownInhibitorDetails Modafinil Cytochrome P450 3A4 Protein Humans UnknownSubstrateInducerDetails