[Levels of amitriptyline and its metabolites in the treatment of depression].

The authors assessed in a 21-day investigation the levels of amitriptyline and its metabolites in plasma and saliva, using the RIA method, in an attempt to reveal the relationship between the therapeutic effect and the assessed concentrations. They did not find a clear relationship between the therapeutic effect and plasma levels; when eliminating extreme maximal and minimal values, we may speak of concentrations where clinical improvement is recorded: from 150 to 450 micrograms/l. The concentration in saliva correlated at higher levels with the plasma concentration; this gives a theoretical chance of screening by this method. From the clinical aspect it is essential to express an opinion on the development of side-effects in relation to plasma levels. This problem will be discussed in a subsequent paper.