Plasma levels and urinary excretion of lormetazepam (Noctamid-ampoules; 2 mg/10 ml) were studied after i.v. (0.015 mg/kg b.w.) and after p.o (0.03 mg/kg b.w.) administration of the drug to five patients with cirrhosis of the liver (C) and to five young male volunteers (N). The cirrhotic patients exhibited higher drug plasma levels (Cmax p.o.: 11-43 ng/ml [C] vs. 11-16 ng/ml [N]) and higher AUC0-24 values of the unchanged drug (i.v.: 66-102 ng.h/ml [C] vs. 54-72 ng.h/ml [N]; p.o.: 83-188 ng.h/ml [C] vs. 74-113 ng.h/ml [N]). The absolute bioavailability was increased in the C-group with 57-134% vs. 52-84% [N]. The total plasma clearance of lormetazepam was 3 ml/min/kg in the C-group and 4 ml/min/kg in the N-group and thus within the range known for elderly and young male subjects. Conversely to the parent compound, the AUC-figures of its 3-OH-glucuronide were higher in the N-group (346-434 ng.h/ml) than in the C-group (149-371 ng.h/ml). In 24 h pooled urine samples of both groups, the glucuronide of lorazepam, the N-demethylated metabolite, accounted for approximately 5-14% of the dose fraction excreted as lormetazepam glucuronide. Apart from increased levels of the unchanged drug due to porto-systemic shunt and/or disease-dependent lower glucuronidation rate, the pharmacokinetics of lormetazepam were not altered in cirrhotic patients. It can therefore be concluded that for this group of patients the drug can be administered according to the same dose regimen as that used for normal subjects.

Administration, Oral↗

PubMedDate not supplied

Metabolism of nafronyl in man.

The metabolism of nafronyl (I) has been studied in man. In addition to small amounts of the parent compound, three acidic metabolites were extracted from urine. The chemical structures of all metabolites were determined by using mass spectrometry and [1H]-NMR spectroscopy as tetrahydro-beta-(1-nephthalenylmethyl)-2-furanpropionic acid (II) and two stereoisomers of 3-(1-naphthalenylmethyl)-tetrahydrofuran-2-one-5-propionic acid (III, IV). The biodegradation products III and IV are formed after oxidation of the tetrahydrofuran system in II, hydrolytic ring opening of the gamma-butyrolacton and a subsequent formation of a gamma-butyrolacton ring with the second carboxyl group. The three metabolites represent the major fraction of unconjugated products in the urine of man after administration of nafronyl.

Adult↗