Antipyrine clearance and metabolism in patients with psoriasis.

The kinetic parameters of antipyrine obtained from saliva samples and the appearance of major antipyrine metabolites (4-hydroxyantipyrine, norantipyrine and 3-hydroxymethylantipyrine) in urine samples were measured in 10 patients with psoriasis (six nonsmokers and four smokers) and in 20 healthy subjects (11 nonsmokers and nine smokers). The volume of distribution and total clearance of antipyrine were not significantly different between psoriatric patients and control subjects subdivided according to smoking habit. However, antipyrine half-life was significantly (P less than 0.05) shorter in nonsmoking psoriatrics than in nonsmoking controls. There were no significant differences in mean values for the amounts (% dose) and partial clearances for production of major antipyrine metabolites between non-smoking patients and non-smoking controls, between smoking patients and smoking controls, and between patients overall and controls overall. The total clearance of antipyrine and the partial clearances of antipyrine to its three main metabolites were significantly (P less than 0.05 to 0.01) greater in smoking controls than in nonsmoking controls, and the total clearance of antipyrine and the partial clearance to 4-hydroxyantipyrine were significantly (P less than or equal to 0.05) greater in smoking patients than in nonsmoking patients. These findings provide no evidence that psoriasis is associated with an alteration in hepatic microsomal monooxygenase activity, at least insofar as the formation of major antipyrine metabolites is concerned.