Modafinil
Modafinil is a wakefulness-promoting medicine. Its label sets out three specific licensed uses, all of them sleep disorders diagnosed by a clinician, and carries a rash warning that asks for an unusually low threshold to stop.
Key points
- The label indicates modafinil to improve wakefulness in adult patients with excessive sleepiness associated with narcolepsy, obstructive sleep apnoea, or shift work disorder.
- In obstructive sleep apnoea it is indicated to treat the excessive sleepiness and not as treatment for the underlying obstruction.
- The label directs discontinuing modafinil at the first sign of rash, unless the rash is clearly not drug-related.
- Serious rash requiring hospitalisation and discontinuation of treatment has been reported in association with its use.
How it works
Modafinil promotes wakefulness. What the label is careful about is the boundary of that effect rather than the mechanism: in obstructive sleep apnoea it treats the excessive sleepiness and is not a treatment for the underlying obstruction. Someone using it for sleepiness caused by untreated apnoea still has untreated apnoea, which is the part that carries the cardiovascular and accident risk.
That distinction is the most useful thing on the page. It is also why all three licensed uses start from a diagnosis rather than from a symptom.
Safety specific to modafinil
Serious rash. The label’s instruction is to discontinue modafinil at the first sign of rash, unless the rash is clearly not drug-related. That is a deliberately low threshold, and the reason is on the same label: serious rash requiring hospitalisation and discontinuation of treatment has been reported in association with the use of modafinil.
The reported paediatric rate gives the scale: rashes occurred in 0.8%, 13 per 1,585 paediatric patients under 17, and those included one case of possible Stevens-Johnson Syndrome and one case of apparent multi-organ hypersensitivity reaction.
Ciclosporin. Blood concentrations of ciclosporin may be reduced by modafinil, which matters for anyone taking an immunosuppressant where the level is the point.
When to seek urgent care
Any rash appearing after starting modafinil is a reason to stop and seek medical advice rather than to watch it, given the label’s own instruction. A rash with blistering, mouth or eye involvement, or fever needs emergency assessment.