Pharmacodynamic effects on alertness of single doses of armodafinil in healthy subjects during a nocturnal period of acute sleep loss

Objective. To assess the pharmacodynamics of armodafinil compared with modafinil and placebo on measures of alertness in healthy volunteers undergoing sleep loss. Research design and methods: In a double-blind, active- and placebo-controlled, parallel-group study, 107 healthy male volunteers (aged 18-40 years) were randomized to receive a single oral dose of armodafinil (100, 150, 200, or 300mg), modafinil (200mg), or placebo administered at 19:25 h. Main outcome measures: The primary outcome was the Maintenance of Wakefulness Test (MWT), administered every 2 hours from 22:00-08:00 h. Secondary outcomes included the Psychomotor Vigilance Task (PVT) and the Karolinska Sleepiness Scale. Blood samples for pharmacokinetic analysis were collected hourly. Adverse events were evaluated throughout the 2-day laboratory stay and by telephone on day 9. Results: All four doses of armodafinil, and the dose of 200mg modafinil, improved wakefulness as measured by increased MWT latencies (treatment effect, p < 0.0001) and reduced PVT lapses of attention (treatment effect, p < 0.0001). The magnitude and duration of these effects at the later time points appeared to be dose and concentration dependent. Armodafinil at 200 mg resulted in comparable C-max, a later t(max), and higher plasma concentrations 6-14 hours post-drug administration than with 200 mg modafinil. Following armodafinil, longer MWT latencies and fewer PVT lapses 6 to approximate to 14 hours post-drug administration were observed compared with modafinil. Armodafinil doses were well tolerated, with the most common adverse events including abdominal pain, nausea, and headache. There were reports of tachycardia/palpitations. Decreased mean sleep efficiency and increased mean blood pressure were also observed. Conclusion: Armodafinil improved alertness at all doses studied. Relative to modafinil 200mg, armodafinil 200mg showed a comparable peak plasma concentration with higher concentrations 6-14 hours post-drug, and improved wakefulness and sustained attention for a longer time post-dose. Both drugs were well tolerated; however, further research on the efficacy, safety, and tolerability of armodafinil in patients with disorders of excessive sleepiness (ES) is required.