Tacrine in Alzheimer's disease

Abstract

The efficacy and safety of tacrine (tetrahydroaminoacridine) plus lecithin were studied in a randomised, double-blind, placebo-controlled, crossover study. Patients with probable Alzheimer's disease were selected from those attending the memory clinic at a psychiatric hospital. Of the 89 patients included, 24 were withdrawn, 19 because of side-effects, 4 with other illnesses, and 1 for non-compliance. The active treatment was the maximum tolerated dose of tacrine up to 150 mg daily plus 10.8 g lecithin daily. Patients were randomly assigned to active or placebo treatment and crossed over after 13 weeks' treatment and 4 weeks' washout to the other treatment. The main outcome measures were the mini mental state examination (MMSE), the abbreviated mental test score (AMTS), and the carer's rating of the activities of daily living scale. Analysis for the 65 patients who completed the trial showed a significant beneficial effect of tacrine over placebo in the MMSE score (p less than 0.0001; 95% confidence interval for group change on tacrine over that on placebo 1.67-3.71); 29 (45%) patients showed an improvement of 3 or more points on tacrine compared with 7 (11%) during placebo. The findings with the AMTS were similar (p = 0.0001; 95% CI 0.36-1.38) but the ADL score showed no significant treatment effect. There was substantial variation in response among the subjects. Dose-dependent rises in serum liver enzymes were common but reversible. Tacrine produced an improvement in key outcome measures roughly equivalent to the deterioration which might have occurred over 6-12 months. The clinical relevance of the findings is a matter for individual judgment.