Non-specific efficacy of psychotropic (and also other) drugs can be influenced by placebo effect including fashion and cultural differences in expectations, by genetic variability, e.g. in degrading enzymes and therefore in drug availability and pharmacokinetics, and largely by adherence to treatment. In other words, the drugs which we trust in, metabolize slowly and swallow obediently are much more efficient than that with minimum psychological effect, rapidly destroyed or even not used. These three variables also interact with each other.