dextromethorphan and Liver-Diseases

The primary objective of this study was to determine how the pharmacokinetics of sabeluzole, an investigational drug with specific effects on memory and learning abilities, are affected by chronic liver disease. Since sabeluzole is metabolised by CYP2D6, a secondary objective was to study the correlation between CYP2D6 activity (as assessed by the dextromethorphan dextrorphan metabolic ratio) and hepatic dysfunction.. The single-dose pharmacokinetics of sabeluzole (10 mg) was compared in 10 healthy Caucasian subjects and 10 patients with severe hepatic dysfunction. The urinary dextromethorphan/dextrorphan (DMP/DRP) metabolic ratio was determined after intake of 20 mg dextromethorphan (NODEX capsules).. The terminal half-life of sabeluzole was significantly prolonged in subjects with severe hepatic dysfunction vs healthy subjects (respectively 39.3 +/- 11.5 h; 17.5 +/- 10.2 h (mean +/- s.d.)). The areas under the curve (AUC) were significantly higher in subjects with severe hepatic dysfunction than in healthy volunteers (681 +/- 200 ng ml(-1) h vs 331 +/- 282 ng ml(-1) h). There was a significant correlation between the AUC(0,infinity) and the DMP/DRP metabolic ratio in healthy volunteers and subjects with severe hepatic dysfunction. AUC was greater and elimination of sabeluzole slower in poor metabolizers compared with extensive metabolizers.. These results suggest that a) sabeluzole dose should be reduced in patients with severe hepatic dysfunction and b) the AUC of sabeluzole is linked to individual CYP2D6 activity.

Topics: Adult; Antitussive Agents; Cytochrome P-450 CYP2D6; Dextromethorphan; Humans; Liver; Liver Diseases; Male; Middle Aged; Oxidation-Reduction; Piperidines; Thiazoles

1. The O-demethylation of dextromethorphan to dextrorphan exhibits a genetically-controlled polymorphism, co-segregating with that of debrisoquine hydroxylation. Dextromethorphan has been proposed as a test compound to assess drug oxidation polymorphism. 2. We studied the effects of liver disease of varying severity on dextromethorphan oxidation capacity. Phenotyping was performed using the urinary dextromethorphan/dextrorphan metabolic ratio after oral administration of 40 mg dextromethorphan hydrobromide in 56 patients with cirrhosis and in 51 patients with moderately severe liver disease. 3. Dextromethorphan oxidation capacity was impaired in cirrhotic patients and, to lesser extent, in non cirrhotic patients, as compared with 103 control subjects. 4. The impairment in dextromethorphan oxidation induced by liver disease, was however, much less than that caused by the genetic deficiency. As a result, the prevalence of the poor metabolizer phenotype remained in the same range in patients with cirrhosis (1.8%) and with moderately severe disease (2.0%) as in controls (3.9%). 5. This observation shows that, although liver disease causes some impairment of dextromethorphan O-demethylation, this impairment is not sufficient to modify the assignment of phenotypes.

Topics: Adult; Aged; Aged, 80 and over; Creatinine; Dextromethorphan; Dextrorphan; Female; Humans; Levorphanol; Liver Cirrhosis, Alcoholic; Liver Diseases; Liver Function Tests; Male; Middle Aged; Oxidation-Reduction; Phenotype