modafinil

Modafinil is a wakefulness-promoting medication used to treat excessive daytime sleepiness associated with narcolepsy, shift work sleep disorder, and obstructive sleep apnea/hypopnea syndrome. It is taken by mouth and typically prescribed in daily doses, with regulation varying by country. In some places it is also used off-label to counter fatigue or for cognitive enhancement, though such use is not universally approved and depends on local guidelines.

The exact mechanism of modafinil is not fully understood. It is believed to promote alertness through multiple pathways, including weak inhibition of the dopamine transporter which increases dopamine in the brain, and possible effects on orexin/hypocretin systems and other neurotransmitters. Pharmacokinetically, modafinil has an oral bioavailability of about 80% and a half-life around 12 to 15 hours in adults. It is primarily metabolized in the liver and excreted in the urine.

Typical dosing is 100 to 200 mg once daily in the morning, with adjustments up to 400 mg per day in some cases depending on response and tolerance. Safety considerations include common side effects such as headache, nausea, dizziness, and nervousness. Serious adverse events are rare but can include severe skin reactions (e.g., Stevens–Johnson syndrome) and hypersensitivity. Modafinil can interact with other medications, including hormonal contraceptives, and caution is advised in individuals with cardiovascular, liver, or psychiatric conditions. In the United States, modafinil is a Schedule IV controlled substance requiring a prescription.

Modafinil was developed in the late 20th century by the French company Lafon and later marketed as Provigil by Cephalon after regulatory approval in the United States in 1998; it is now available under various brand names worldwide.