Positive Data Soon On SB's Partial Muscarinic Antagonist?

SmithKline Beecham has compiled what promises to be positive data from two efficacy studies for its muscarinic partial agonist SB202026, a candidate treatment for symptoms of Alzheimer's disease. A preliminary presentation on this data was given at the Collegium Internationale Neuropsycho-pharmacologicum held in Melbourne, Australia last week. SB researcher Tim Tasker said that the company will not be revealing full details of the data until a neuroscience meeting in Osaka, Japan late this year.

Dr Tasker said that SB's two placebo-controlled studies involve a total of 750 patients, all with suspected mild-to-moderate Alzheimer's disease as diagnosed by the DSM-1V rating scale. Both trials were of fairly short duration (14 weeks), and assessed a range of doses of SB202026. The drug performed better than placebo at all the doses tested, as measured by the ADAS-Cog scale. Furthermore, on the CIBIC scale (a clinician-based impression of improvement rating), SB202026's superiority to placebo approached significance from week four, suggesting that a tangible improvement was observed.

Preliminary Efficacy Dr Tasker would not say much about the efficacy of the drug, but on questioning revealed that the ADAS-Cog improvement was around three points. This would put its benefit at around the same level as that seen with the first available drug to target acetylcholine, Warner-Lambert's cholinesterase inhibitor Cognex (tacrine). Turning to the tolerability, Dr Tasker noted that all the doses tested were well-tolerated, and at the lower end of the scale the tolerability was indistinguishable from placebo. Efficacy was seen at the higher end of the dose spectrum, but Dr Tasker confirmed that "enhancement of cognition occurs at doses not associated with side effects." The drop-out rate was between 4% and 11%, similar to placebo.