Short answer: Armodafinil (Nuvigil) is the longer-lasting half of modafinil (Provigil). Modafinil is a 50:50 mix of R and S forms; armodafinil is only the R form.1 Both are approved for the same three sleepiness conditions and both are Schedule IV.2 Label doses differ: 200 mg for Provigil, 150 to 250 mg for Nuvigil. We found no head-to-head efficacy trial.
| Modafinil (Provigil) | Armodafinil (Nuvigil) | |
|---|---|---|
| What it is | 1:1 mix of R- and S-modafinil1 | R-modafinil only2 |
| Approved for | Excessive sleepiness from narcolepsy, obstructive sleep apnea or shift work disorder, in adults1 | The same three conditions, in adults2 |
| Tablets | 100 mg and 200 mg1 | 50, 150, 200 and 250 mg2 |
| Label dose: narcolepsy or sleep apnea | 200 mg once in the morning; up to 400 mg was tolerated, with no consistent extra benefit1 | 150 to 250 mg once in the morning; in sleep apnea, no consistent extra benefit above 150 mg2 |
| Label dose: shift work | 200 mg about 1 hour before the shift1 | 150 mg about 1 hour before the shift2 |
| Half-life | About 15 hours (effective, after repeated doses); the S form leaves about 3 times faster than the R form1 | About 15 hours (apparent terminal)2 |
| Time to peak | 2 to 4 hours; food can delay it about 1 hour1 | About 2 hours fasted; food can delay it 2 to 4 hours2 |
| Most common side effects (5% or more) | Headache, nausea, nervousness, runny nose, diarrhea, back pain, anxiety, insomnia, dizziness, indigestion1 | Headache, nausea, dizziness, insomnia2 |
| Stopped for side effects in label trials | 8% vs 3% on placebo1 | 7% vs 4% on placebo2 |
| Controlled substance | Schedule IV1 | Schedule IV2 |
Mostly. Modafinil is made of two mirror-image forms that do not turn into each other. The R form lasts about three times longer than the S form, and at steady state about 90% of the modafinil left in the blood before the next dose is the R form.1 Armodafinil is that R form on its own. The Nuvigil label says a single 50 mg dose of armodafinil and a 100 mg dose of modafinil give almost the same R-form blood curve.2
Because the S form in modafinil clears fast (half-life about 4 hours), modafinil levels drop off more quickly after the peak. At steady state, 200 mg of Nuvigil gave about 37% higher peak levels and 70% higher total exposure than 200 mg of Provigil.2
A pooled analysis of three single-dose studies in healthy adults found both had a terminal half-life of about 13 hours, but total exposure was 33% to 40% higher with armodafinil milligram for milligram, with higher levels late in the day.3 That study measured blood levels, not wakefulness, and was run by the maker of both drugs.
More detail: the Modafinil and Armodafinil guides.