Timolol and atenolol: relationships between oxidation phenotype, pharmacokinetics and pharmacodynamics.

Abstract

The pharmacokinetics and pharmacodynamics of atenolol and timolol were studied in six extensive and four poor metabolisers of debrisoquine. There was a significant correlation between the debrisoquine to 4‐ hydroxydebrisoquine ratio and the area under the plasma concentration time curve (AUC) for timolol (rs = 0.75, P less than 0.02). The mean of the AUC values for timolol was significantly greater in the poor metabolisers than in the extensive metabolisers (P less than 0.05). There was a significant correlation between the debrisoquine to 4‐ hydroxydebrisoquine ratio and beta‐adrenoceptor blockade 24 h after dosing with timolol (rs = 0.66, P less than 0.05). The mean degree of beta‐adrenoceptor blockade was significantly greater in the poor metabolisers than in the extensive metabolisers 24 h after dosing with timolol (P less than 0.01). There was no relation between the debrisoquine to 4‐hydroxydebrisoquine ratio and the pharmacokinetics or pharmacodynamics of atenolol. 1985 The British Pharmacological Society