Theophylline kinetics in relation to age: the importance of smoking.

Publisher Website
Google Scholar
Abstract
1 Single dose studies of theophylline kinetics were compared in groups of young and elderly smokers and non‐smokers to assess the effect of age on theophylline absorption and the effect of smoking on drug metabolising enzyme activity in old age. 2 The rate and extent of absorption was not affected by age. Distribution and elimination kinetics were similar in young and elderly non‐smokers. 3 In young subjects the elimination half‐life of theophylline was shorter and clearance was significantly greater in smokers than in non‐smokers. 4 In the elderly mean elimination half‐life was significantly shorter in smokers and their plasma clearance was 40% higher than in non‐smokers. The statistical difference for clearance was at the 7% level of significance. 5 These data indicate that ageing per se does not affect theophylline elimination and also that induction of theophylline metabolism due to smoking occurs in old age. Smoking is a variable that should be taken account of when assessing drug metabolism in elderly patients.