Treatment effects of EGb 761 and cholinesterase inhibitors--why available studies do not demonstrate superiority of the latter

Abstract

Based on simple comparisons of drug-placebo differences found in clinical trials, it has repeatedly been concluded that EGb 761 is less effective in the treatment of Alzheimer's disease than cholinesterase (ChE) inhibitors. However, the data of pivotal studies with both types of drugs show that drug-placebo differences in cognitive outcomes are more influenced by the degrees of deterioration of the placebo groups than by changes of the actively treated groups. Since the former are determined by characteristics of the patient samples and the therapeutic environment, but not by drug effects, it is concluded that direct comparisons of drug-placebo differences are inappropriate to assess the relative potencies of anti-dementia drugs. Comparisons have to take into account the different unspecific influences. The currently available data do not support the notion of superiority of ChE inhibitors over EGb 761.