Clozapine metabolism rate as a possible index of drug-induced granulocytopenia.

A possible relationship between haematological adverse reactions and clozapine (CLZ) metabolism rate was studied. Sixteen chronic schizophrenic outpatients (mean age 34.62 years +/- 7.56 SD) were treated with CLZ, 75-600 mg/daily for 9 weeks. CLZ and norclozapine (NCLZ) plasma levels were determined weekly, contemporarily with blood cell counts. CLZ plasma levels ranged from 25 to 1270 ng/ml (mean 266.27 ng/ml +/- 197.44 SD), while NCLZ plasma levels ranged from 25 to 1280 ng/ml (mean 169.0 ng/ml +/- 127.94 SD). NCLZ/CLZ ratio ranged from 0.13 to 1.72 (mean 0.72 +/- 0.28 SD). Leukocyte count ranged from 5.2 to 18.8 10(9)/l (mean 9.37 10(9)/l +/- 2.94 SD) and neutrophil count ranged from 1.8 to 13.4 10(9)/l (mean 5.73 +/- 2.57 SD). No correlation was found between CLZ dosage and NCLZ plasma levels. Both CLZ and NCLZ plasma levels correlated positively with neutrophil count (CLZ: P = 0.001, r = 0.26; NCLZ: P = 0.01, r = 0.20). The correlation between NCLZ/CLZ plasma level ratio and neutrophil count was significantly negative (P = 0.002, r = 0.25). These preliminary data suggest that the NCLZ/CLZ ratio, as an index of CLZ metabolism, might be a possible risk factor associated with CLZ treatment.

Quazepam versus triazolam in patients with sleep disorders: a double-blind study.

Quazepam, a recently introduced long-half-life benzodiazepine, seems to have a more specific hypnotic activity and a physiological mechanism of action. The present study evaluated clinical efficacy and eventually rebound symptoms after the treatment with quazepam and triazolam. Sixty-five patients, affected by sleep disorders, were entered into the study. Patients were treated with a placebo for four days and, if no amelioration of insomnia was observed, they were allocated randomly to receive 15 mg of quazepam (32 patients) or 0.5 mg triazolam (33 patients) for eight weeks and finally the placebo for another week. The sleep quality, the sleep efficacy, the unwanted effects and the rebound effects had been assessed by specific evaluation scales. Both of the drugs showed a hypnogenic efficacy but patients treated with quazepam had significantly less night awakenings; at the treatment's interruption, only the patients treated with triazolam had longer awakenings and rebound symptoms. In conclusion, quazepam seems to have a good hypnotic effect without inducing rebound effects. On the contrary, triazolam turned out to be just a hypnoinducent drug with higher risks of rebound effects after withdrawal.

Comparative pharmacokinetic study of chewable and conventional carbamazepine in children.

Fifteen children (7 boys and 8 girls) with generalized tonic-clonic seizures (GTCS) and partial seizures with elementary or complex symptomatology, treated with carbamazepine (CBZ) alone (n = 7) or in combination with either phenobarbital (PB, n = 6) or clobazam (CLB, n = 2) given for at least 3 months at stable individualized doses and regimens, entered an open, within-patient, change-over study of consecutive periods, each lasting 2 weeks. During period 1, conventional CBZ was given; during period 2, a chewable CBZ formulation was substituted for conventional CBZ and given at the same total daily dosage with the same schedule as in period 1. Blood samples for measuring plasma concentration of both total CBZ and CBZ-10,11 epoxide (CBZ-E) were taken on the last day of each period. No significant difference between the two periods was noted in the mean +/- SD of Cmax, Css mean, and area under the curve (AUC) of total CBZ and CBZ-E. The two different CBZ formulations, administered at the same total daily dosage, can be considered bioequivalent.