Chemotherapy with neuroleptics. Clinical and pharmacokinetic aspects with a particular view to depot preparations.

Attempting to improve long-term neuroleptic treatment of schizophrenic patients several injectable depot neuroleptics have been developed. Moreover pharmacokinetic data increasingly have been clinically applied. On this background the purpose of the present paper has been to make an updated review of the clinical and pharmacokinetic knowledge of depot neuroleptic treatment. First, general aspects of antipsychotics have been summarized, and an outline of methodological questions relevant to clinical-pharmacological trials are given. Subsequently general aspects including pros & cons of depot administration are examined. Finally the available data of the various depot preparations have been scrutinized. It is concluded that our present pharmacokinetic knowledge of the particular preparations is incomplete. Thus more information of clinical relevant aspects are needed, e.g., the existence of a therapeutic range, maximum/minimum concentration ratio, and the significance of active metabolites. Comparing the various depot neuroleptics, no significant differences are seen regarding the clinical effects. However, the decanoate esters seem clinical superior to the corresponding enanthate esters explained by the more flat concentration curve of the decanoates. Apart from that, a comparison of the pharmacokinetic data is difficult because of the heterogenecy of the available data. Haloperidol, clopenthixol and perphenazine decanoates are among the best examined preparations in pharmacokinetic respects. A controlled double-blind comparative study of these preparations would be of interest.