Modafinil

How it works

It promotes wakefulness through a mechanism that is not fully defined but involves enhanced dopaminergic signalling via inhibition of dopamine reuptake, with effects on other wake-promoting neurotransmitter systems.

Prescribing in practice

• Stop immediately and seek advice if any rash develops, as serious skin and hypersensitivity reactions including Stevens-Johnson syndrome have been reported.
• It induces CYP3A4 and can reduce the efficacy of hormonal contraceptives, so additional or alternative contraception is needed.
• Use cautiously in those with anxiety, a history of psychosis or cardiovascular disease, and it should be avoided in significant uncontrolled hypertension or arrhythmia.

Monitoring

Monitor blood pressure and heart rate, and review for new or worsening psychiatric symptoms such as anxiety, agitation or psychosis during treatment.

Counselling the patient

• Report any skin rash, mouth ulcers or blistering at once and stop the medicine.
• Hormonal contraception may be less reliable, so use additional contraceptive measures.
• Take in the morning to support daytime wakefulness without disrupting night-time sleep.

Evidence & guidelines

MHRA advice restricts modafinil's licensed use largely to narcolepsy following review of cardiovascular, psychiatric and serious skin-reaction risks.