The effects of salbutamol and cimetidine, alone and in combination, on pentagastrin-stimulated gastric secretion have been studied in conscious dogs with gastric fistulae. Salbutamol 24nmol/kg·h alone and cimetidine 4μmol/kg·h alone inhibited acid by up to 69%, cimetidine 8 μmol/kg·h produced up to 87% inhibition and the combination of cimetidine 4 μmol/kg·h and salbutamol 24 nmol/kg·h almost totally inhibited acid (up to 99%). The pharmacokinetics of these inhibitions were studied and salbutamol and/or cimetidine caused a complex uncompetitive inhibition of pentagastrin-stimulated acid. The inhibitory combination of the two drugs was a