norclozapine and Sialorrhea

Hypersalivation is known as a frequent, disturbing, and socially stigmatizing side effect of therapy with the atypical antipsychotic clozapine. It has been shown that the addition of the anticholinergic pirenzepine is able to reduce clozapine-induced hypersalivation, probably by blocking M4-receptors. Nevertheless, a pharmacokinetic interaction between both compounds cannot be excluded.. In this pilot study, 29 schizophrenic patients (ICD-10; 51.7 % female; age: 36.7 +/- 8.7 years [mean +/- SD]) were included. Serum concentrations of clozapine and its pharmacologically active metabolite N-desmethylclozapine were determined under steady-state conditions by automated HPLC with UV detection before and after addition of pirenzepine for 3 days.. Significantly fewer patients reported hypersalivation after addition of pirenzepine (69 % vs. 34.5 %, P = 0.002). No significant differences of clozapine and N-desmethylclozapine serum levels before (329 +/- 181 ng/ml and 218.0 +/- 123.4 ng/ml, respectively) and 3 days after (336 +/- 215 ng/ml and 235.9 +/- 164.4 ng/ml, respectively) addition of pirenzepine were found. In three patients, however, clozapine serum levels increased; this was probably unrelated to pirenzepine.. In conclusion, treatment of clozapine-induced hypersalivation with pirenzepine is a recommendable combination with low risk of additional side effects.

Topics: Adult; Antipsychotic Agents; Chromatography, High Pressure Liquid; Clozapine; Cross-Over Studies; Dose-Response Relationship, Drug; Drug Interactions; Female; Humans; Male; Middle Aged; Muscarinic Antagonists; Pilot Projects; Pirenzepine; Schizophrenia; Sialorrhea; Spectrophotometry, Ultraviolet

Clozapine is associated with non-neurological side effects that can be subjectively unpleasant and/or clinically serious. We sought to: (i) assess the nature and prevalence of side effects experienced by patients receiving maintenance treatment with clozapine and (ii) explore the relationship between clozapine plasma concentration and side effect burden. Patients were receiving clozapine maintenance treatment. Open questioning followed by systematic enquiry using the Antipsychotic Non-neurological Side Effects Rating Scale were used to assess side effects. Trough plasma clozapine and norclozapine concentrations were measured. One hundred and three patients participated. On open questioning, 61 patients reported a total of 117 side effects, whereas systematic enquiry identified an additional 649 side effects, with each patient reporting at least one. Clozapine plasma concentrations were significantly but weakly correlated with total Antipsychotic Non-neurological Side Effects Rating Scale score (Pearson correlation=0.29, P<0.004). Patients with a plasma clozapine concentration >0.25 mg/l were significantly more likely to have moderate/severe side effects than patients with lower plasma concentrations (63/76 vs. 12/23, chi=9.07, d.f.=1, P<0.01). The side-effect burden associated with maintenance clozapine treatment is high and the true extent can only be ascertained by systematic inquiry. The use of target plasma concentrations below those used for acute treatment should be explored as a strategy for minimizing side effects.

Topics: Adolescent; Adult; Aged; Antipsychotic Agents; Clozapine; Disorders of Excessive Somnolence; Female; Humans; Male; Middle Aged; Prevalence; Psychotic Disorders; Schizophrenia; Sexual Dysfunction, Physiological; Sialorrhea

Monitoring plasma clozapine concentrations may play a useful role in the management of patients with schizophrenia, but information on the relationship between the plasma levels of the drug and response is still controversial.. The purpose of this study was to assess the relationship between plasma concentrations of clozapine and its weakly active metabolite norclozapine and clinical response in patients with schizophrenia resistant to conventional neuroleptics.. Forty-five patients, 35 males and ten females, aged 19-65 years, were given clozapine at a dosage up to 500 mg/day for 12 weeks. Steady-state plasma concentrations of clozapine and norclozapine were measured at week 12 by a specific HPLC assay. Psychopathological state was assessed at baseline and at week 12 by using the Brief Psychiatric Rating Scale, and patients were considered responders if they showed a greater than 20% reduction in total BPRS score compared with baseline and a final BPRS score of 35 or less.. Mean plasma clozapine concentrations were higher in responders (n=18) than in non-responders (n=27) (472+/-220 versus 328+/-128 ng/ml, P<0.01), whereas plasma norclozapine levels did not differ between the two groups (201+/-104 versus 156+/-64 ng/ml, NS). A significant positive correlation between plasma levels and percent decrease in total BPRS score was found for clozapine (r(s)=0.371, P<0.02), but not for norclozapine (r(s)=0.162, NS). A cutoff value at a clozapine concentration of about 350 ng/ml differentiated responders from non-responders with a sensitivity of 72% and a specificity of 70%. At a cutoff of 400 ng/ml, sensitivity was 67% and specificity 78%. The incidence of side effects was twice as high at clozapine concentrations above 350 ng/ml compared with lower concentrations (38% versus 17%).. These results suggest that plasma clozapine levels are correlated with clinical effects, although there is considerable variability in the response achieved at any given drug concentration. Because many patients respond well at plasma clozapine concentrations in a low range, aiming initially at plasma clozapine concentrations of 350 ng/ml or greater would require in some patients use of unrealistically high dosages and imply an excessive risk of side effects. Increasing dosage to achieve plasma levels above 350-400 ng/ml may be especially indicated in patients without side effects who failed to exhibit amelioration of psychopathology at standard dosages or at lower drug concentrations.

Topics: Adult; Aged; Antipsychotic Agents; Clinical Trials as Topic; Clozapine; Conscious Sedation; Constipation; Dizziness; Dose-Response Relationship, Drug; Drug Resistance; Female; Follow-Up Studies; Humans; Male; Middle Aged; Psychiatric Status Rating Scales; Schizophrenia; Sialorrhea; Tachycardia; Treatment Outcome; Weight Gain