Effect of 2-diethylaminoethyl-2,2-diphenylvalerate hydrochloride (SKF 525-A) on sulphacetamide distribution and excretion in rats.

1. Administration of 2-diethylaminoethyl-2,2-diphenylvalerate hydrochloride (SKF 525-A), 40 mg/kg, i.p., simultaneously or 40 min before sulphacetamide sodium, 100 mg/kg, i.p., was associated with a three-fold increase in sulphacetamide plasma concentration of rats. This effect was no longer evident after 30 minutes.2. The augmentation in sulphacetamide plasma concentration was associated with parallel increases in the muscle, kidney and brain tissue. The stomach was the only organ that contained less sulphacetamide.3. When sulphacetamide was administered i.v., a similar phenomenon was observed but the differences were less marked.4. Pretreatment with SKF 525-A was associated with decreased excretion of sulphacetamide by the kidney.5. It is concluded that SKF 525-A may alter the distribution and excretion of drugs as well as inhibiting drug metabolizing enzymes.