We have measured the metabolites (demethylated and hydroxylated) of amitriptyline in a group of seven normal volunteers. They were phenotyped as extensive or poor metabolizers using debrisoquine and bufuralol. The results demonstrate that the oxidative metabolism (aliphatic hydroxylation) of amitriptyline is under the same genetic control as that of debrisoquine and bufuralol. However, phenotypic polymorphism cannot be used to predict amitriptyline blood concentration after a single oral dose, since the principal metabolic pathway of amitriptyline is demethylation and not aliphatic hydroxylation.

The purpose of the present study was to evaluate zuclopenthixol acetate in Viscoleo, a new preparation to be administered once every 3 days, in the early treatment of acute psychotic episodes and acute deterioration of chronic psychosis. 21 cases were included in the study: patients received 1 to 3 injections. Clinical evaluation was made at 24, 48 and 72 hours after each injection, using the Clinical Global Impressions (CGI) and the Brief Psychiatric Rating Scale (BPRS). Results at end-point indicated a marked or moderate therapeutic effect in the 11 cases of acute psychosis. A statistically significant decrease was observed for the total BPRS score as well as for its subscales. Among 8 cases of exacerbation of chronic psychosis, 4 patients showed a moderate therapeutic effect, and minimal or no effect was found in the other 4 subjects. The total BPRS decreased significantly, but to a lesser extent than for acute psychosis. Two patients suffering from mania showed a moderate therapeutic effect according to CGI. 8 cases of acute psychosis and 5 cases of chronic psychosis did not suffer from any neurological side-effects. Plasma concentration measurements suggest that a dose of 50 mg per 3 days may be sufficient for early treatment of most acutely ill psychotic patients.

Antipsychotic drugs (neuroleptics) are candidates for plasma concentration monitoring, but not all agents have the same potential in this respect. The present review analyses the available data on the kinetics and metabolism of fluphenazine, perphenazine, thiothixene, flupenthixol, clopenthixol, haloperidol, pimozide, penfluridol, sulpiride and clozapine. Although some of the drugs described in this review have been in use for many years, knowledge of their pharmacokinetics is still only approximate. This is primarily because determination in biological fluids is not always feasible. Accordingly, analytical methods useful for pharmacokinetic studies or plasma concentration monitoring of these antipsychotic drugs are discussed. With the exception of sulpiride, all the neuroleptics reviewed share some basic pharmacokinetic properties: good gastrointestinal absorption but reduced systemic availability because of hepatic first-pass metabolism, high hepatic clearance and a large apparent volume of distribution leading to an apparent elimination half-life of about 24 hours for most of these compounds. The renal elimination is negligible and it seems that these drugs do not possess active metabolites. The pharmacokinetic properties of antipsychotic drugs are important for the inclusion of a set of drugs in a psychiatric institution where there is a possibility of drug concentration monitoring. In addition, the availability of a depot preparation is of importance. These factors are discussed in view of the experience made during the last years in the University Psychiatric Institutions of Geneva.