Abstract
1. Salicyl-azo-sulphapyridine was recovered mainly as azo-cleavage products in conventional rats after oral as well as after intraperitoneal administration of the drug.
2. After administration of salicyl-azo-sulphapyridine to germ-free rats, the recovery of azo-cleavage products was 1·7% of the dose after oral and 10% of the dose after intraperitoneal dosage.
3. It is concluded that salicyl-azo-sulphapyridine is reductively cleaved at the azo linkage by the action of the intestinal microflora and that azo-reductases in the tissues play a minor role.