Lack of biological interaction of alprenolol and salicylate in man

Summary

Theoretically the effect of the β-blocking agent alprenolol might be reinforced by concomitant administration of salicylate, as both drugs are partly excreted as glucuronides and both appear to have a saturable mechanism for biotransformation. The β-blocking effect of alprenolol administered alone and with sodium salicylate has been compared by studying the inhibition of the hemodynamic response to physical work. Blood samples were collected immediately after exercise and the serum analysed for unchanged alprenolol. The urinary excretion of alprenolol, alprenolol glucuronide and salicylate and its metabolites was followed for more than 24 h. The administration of sodium salicylate did not influence significantly the pharmacological effect of alprenolol or its serum levels or half life, nor did it affect the formation of alprenolol glucuronide. The latter drug did not affect the metabolism of salicylate. These results show that therapeutic doses of alprenolol and salicylate are unlikely to give any interaction of clinical importance.