UK drugmaker Shire is reviewing the development pathway for its attention-deficit hyperactivity disorder drug Vyvanse after the drug showed potential in a new indication - the treatment of excessive daytime sleepiness (EDS).

A single dose, randomised, placebo- and active-controlled study, involving 135 subjects, looked at the effect of Vyvanse (lisdexamfetamine dimesylate) 20mg, 50mg, or 70mg compared to a ghost pill or Cephalon's sleep drug Nuvigil (armodafinil 250mg). 

The firm said that all groups met the primary target of improving objective wakefulness compared to placebo, but crucially, Vyvanse 70mg also showed a statistically-significant improvement compared to Nuvigil, giving its shares a little nudge on the London Stock Exchange yesterday. (No significant difference was observed with the 50mg dose and the 20mg formulation didn't perform as well as the comparator drug).  

Also on a positive note, while safety data are limited as patients were only dosed once with the drug, no treatment emergent adverse events were deemed serious or resulted in participants dropping out of the study, it said.

Shire was quick to stress that it is too early to draw any conclusions on comparability between Vyvanse and Nuvigil from the signal finding study alone, but it added that, based on the results, the company is planning to review potential development pathways for the drug with health authorities as a possible EDS treatment option.

Jeffrey Jonas, senior vice president of research and development for Shire’s Specialty Pharmaceuticals business, said the firm is "encouraged by the positive outcomes in both objective and subjective measures in this proof of concept study", but he also noted that "confirmation of these results in larger studies of EDS patients is required".

Vyvanse - a follow-up to the firm’s hugely successful ADHD drug Adderall XR - is a stimulant medication classed as a federally controlled substance because of its potential for abuse and dependence. The drug first hit the US in 2007 for the treatment of children (and subsequently adolescents) with ADHD, and pulled in third-quarter sales of $151 million for the third quarter of last year. 

Several million people in the US are thought to be affected by EDS, creating a sizeable market for therapies to treat the condition.