Vanda Pharmaceuticals reported positive results from a phase II trial of VSF-173, an orally administered stimulant, for the treatment of excessive sleepiness. This randomized, double-blind, placebo-controlled trial enrolled  fifty-five subjects who received three doses of VSF-173 administered at 50 mg, 100 mg and 200 mg and placebo administered at 25 mg, 50 mg and 100 mg at the usual bedtime and at four hours after the first dose.

Efficacy was measured via a series of six Maintenance of Wakefulness Tests (MWT) given two hours apart starting one hour after the first dose, as well as the scheduled daytime recovery sleep following the night time and morning evaluations. Although not statistically significant, VSF-173 demonstrated improvement over placebo on the primary endpoint, the effect of the compound on the first four series of MWT tests.

The mean MWT sleep onset scores for the 50 mg, 100 mg and 200 mg, and placebo groups were 10.3, 12.9, 10.6 and 9.2 minutes, respectively. In a subset of 37 subjects with no observed impairment in pre-dose daytime wakefulness, the mean of all six MWT scores for the 50 mg, 100 mg and 200 mg groups showed improvements of 2.1, 3.4 and 2.1 minutes, respectively, compared to placebo. For the dose group of 100 mg, this observation of improvement was statistically significant (p < 0.05).

During the scheduled daytime recovery sleep, statistically significant, dose-dependent correlations were observed with the following polysomnography (PSG) parameters: increased number of awakenings, decreased sleep efficiency and total sleep time for the first third of the sleep period, and increased wake time after sleep onset for the first 3 hours of the sleep period (p<.05).

Vanda licensed VSF-173 from Novartis Pharma AG. Based on the results, Vanda plans to move forward with the development of the drug.