Metabolic studies of synthetic isojuripidine in the dog and rat

Synthetic isojuripidine, an alkaloid of “Solanum Paniculatum”, was labelled with 3H by Wilzbach's method. In the dog, after single and repeated oral doses, the plasma levels were proportional to the amount administered and the drug seemed to be excreted very slowly. In the rat, after a single oral dose, the tritiated compound was absorbed and then retained by various tissues a long time, less than 1 per cent being eliminated in the urine in a 32 hr period. Over the same interval faecal excretion reached about 55 per cent of the dose. The metabolic pattern was studied at different times after dosing in the plasma of the two species and in the rat liver after lipophilic extraction. The major metabolite was the N-acetyl-derivative in both species. Contrary to what usually occurs, all these metabolites show less polarity than the original drug and this might explain their very slow disappearance from plasma and tissues.