The drug works by suppressing hunger, leading to an energy deficit which burns off excess body fat. This randomised, placebo-controlled phase II study was done in five Danish obesity management centres, and involved 203 obese patients (body mass index 30-40 kg/m2), weighing a mean of just over 100kg. They were prescribed a limited-energy diet and assigned to tesofensine 0.25mg (52 patients), 0.5 mg (50), 1.0 mg (49), or placebo (52), all once daily for 24 weeks. The primary outcome was percentage change in bodyweight. A total of 161 patients completed the study, and an analysis showed that the mean weight loss recorded for placebo and diet was 2.2kg and for tesofensine 0.25mg, 0.5mg and 1.0mg it was 6.7kg, 11.3kg, and 12.8kg respectively.
For the 0.5mg and 1.0mg doses, this represented a weight loss around twice that attained using sibutramine or rimonabant*, the currently-approved therapies in Europe. Blood pressure was increased in the 1.0mg group. The most common side-effects caused by tesofensine were dry mouth, nausea, constipation, hard stools, diarrhoea, and insomnia.