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Armodafinil dosage
This page is a reference summary of published evidence and regulatory documents. It is not a substitute for individual medical advice, and it is not a recommendation to take or avoid any medicine.
Medically reviewed by Dr. Sofia Lindqvist, · Last reviewed 11 August 2026
The standard armodafinil dose is 150mg once daily in the morning for narcolepsy and obstructive sleep apnoea, with some patients using 250mg. For shift work disorder, 150mg is taken approximately one hour before the start of the work shift rather than in the morning.
On this page
Dose by indication
| Indication | Dose | Timing |
|---|---|---|
| Narcolepsy | 150mg once daily (some use 250mg) | Morning, on waking |
| Obstructive sleep apnoea (adjunct) | 150mg once daily (some use 250mg) | Morning, on waking |
| Shift work disorder | 150mg once daily | ~1 hour before the start of the shift |
Hepatic impairment
Armodafinil is metabolised primarily by the liver, and clearance is reduced in patients with severe hepatic impairment. Dose reduction is recommended in this population; prescribers typically use a lower starting dose than the standard 150mg.
Older adults
Clinical experience in patients aged 65 and over is more limited than in younger adults, and drug clearance tends to decrease with age generally. A lower dose or slower titration may be considered in older patients, following the same general caution applied to modafinil in this population.
The modafinil equivalence, and why it is only rough
150mg armodafinil is often described as roughly equivalent to 200mg modafinil in clinical effect. This comparison is useful as a starting point but is not a precise conversion.
Modafinil is a racemic 50/50 mixture of R- and S-enantiomers; armodafinil is the R-enantiomer alone. A given milligram dose of each drug therefore delivers a different balance of enantiomers to the body, and the two drugs’ plasma concentration curves differ in shape even when overall exposure is comparable. That is why “rough” is the accurate word, not an approximate one used loosely.
Practical dosing notes
Armodafinil is not intended to be taken more than once daily. Taking it later in the day increases the likelihood of delayed sleep onset that night, for the same reason described on the modafinil duration page: both drugs have an elimination half-life long enough that a dose taken even a few hours late can still be substantially present at normal bedtime.
What is the standard armodafinil dose?
150mg once daily in the morning for narcolepsy and obstructive sleep apnoea; some patients use 250mg. For shift work disorder, 150mg is taken about an hour before the shift starts.
Is 150mg armodafinil the same as 200mg modafinil?
They are considered roughly equivalent in clinical effect, but “rough” is accurate: the two drugs differ in enantiomer composition and plasma curve shape, so the equivalence is a practical approximation, not a precise conversion.
Does liver impairment change the armodafinil dose?
Yes. Dose reduction is recommended in patients with severe hepatic impairment because clearance is reduced.
Do older adults need a lower dose?
Dose reduction may be considered in older adults, reflecting the general pattern of slower drug clearance with age rather than a specific armodafinil finding.