Clozapine: the correlation between clinical improvement and laboratory parameters

English: In this study, fifteen Black patients suffering from acute schizophrenia were treated with clozapine for a period of 40 days in order to ascertain whether certain laboratory parameters could be utilized to give an indication of the clinical efficacy of clozapine treatment in these patients. S.l.l Therapeutic efficacy Utilizing the B.P.R.S. and F.C. rating scale as indication of the clinical improvement of the patients, it was found that significant clinical improvement occurred upto day 30 whereafter clinical improvement was only slight. Clozapine was well tolerated by all the patients while more than half the patients (53,3%) were fit for unmndhional discharge on completion .of the study. On completion of the study the working capacity of the majority (80%) was satisfactory. 5.1.2 Side effects The most common side effects encountered were daytime sedation which was especially prominent during the early stages of the study and hypersalivation which occurred with equal frequency throughout the study period. Other side effects encountered in descending order of frequency were nausea and vomiting, dizziness, headache, disturbance of visual accomodation, constipation and diarrhoea, disturbed sleep, sweating, inhibition of micturition, and collapse. 5.1.3 Blood pressure and pulse rate Clozapine had no significant' prolongated effect on blood pressure while a significant and sustained rise in pulse rate during the treatment period was noted. It is suggested that this rise in pulse rate could be utilized as a convenient clinical aid in checking patient compliance in patients being treated with clozapine. 5.1.4 Serum concentration of clozapine, clozapine plus metabolites, and metabolites only. 5.1.4.1 No correlation was found between serum levels of clozapine, clozapine plus its metabolites, or its metabolites only and clinical improvement. 5.1.4.2 It was found that on treatment day 5 steady state serum levels of clozapine and of clozapine plus it metabolites had been reached. 5.1.4.3 No auto-induction of the metabolism of clozapine appeared to occur during the treatment period. 5.1.4.4 No accumulation of clozapine or its metabolites appeared to occur during the treatment period. 5.1.4.5 It can be concluded that a certain period of exposure to a more or less constant serum level of clozapine and/or its metabolites is necessary to effect clinical improvement. 5.1.4.6 A significant correlation was found between the lying pulse rate and serum levels of clozapine plus its metabolites. The lying pulse rate can thus offer a reasonable indication of the expected serum levels of clozapine plus its metabolites. 5.1.5 Prolactin serum levels No rise in serum prolactin levels occurred in these patients after institution of treatment with clozapine. Therefore no correlation between clinical improvement and prolactin serum levels could be ascertained. 5.1.6 5-hydroxytryptamine-induced platelet aggregation No enhancement of 5-HT-induced platelet aggregation could be determined in these patients undergoing treatment with clozapine. Therefore no correlation could be established between clinical improvement and enhancement of 5-HT-induced platelet aggregation. 5.1.7 Plasma cholinesterase and red blood cell ace~- cholinesterase activitX' Both the plasma cholinesterase and red blood cell acetylcholinesterase activity fell within the normal range prior to the institution of treatment with clozapine. These parameters can therefore not be used as diagnostic aids in the diagnosis of schizophrenia. The activity of both parameters also fell within the normal range on conclusion of the study. It would thus appear that treatment with clozapine did not significantly affect these·.parameters.