Influence of age on response to ipratropium and salbutamol in asthma

ABSTRACT We studied the differential response to inhaled salbutamol and ipratropium of 29 asthmatic patients, 18 intrinsic, 11 extrinsic, using peak expiratory flow rate (PEFR), forced expira-tory volume in one second (FEV1), and forced vital capacity (FVC). Thirty minutes after a theoreti-cally maximally bronchodilating dose of salbutamol (400,g) or ipratropium (80 ug), second doses frequently caused further bronchodilatation. We suspect that second doses may reach bronchi untouched by the first inhalation. Analysis of variance showed a powerful intrinsic versus extrinsic effect, and there were clearly differences between patients in their response to treatment (patient versus drug interaction) but these differences were not removed by dividing the patients into intrinsic and extrinsic groups. Results for the group as a whole favoured salbutamol, but examination of individual results by a pattern-recognition technique showed ipratropium equally effective in eight patients and more effective in three. All patients with a definite predominant salbutamol response were less than 40 years old. The response to salbutamol declined significantly with age, whereas that to ipratropium did not. In general in patients aged less than 40 years salbutamol is the drug of choice. With advancing age, and the apparent decline of fl-adrenergic responsiveness, the initially com-paratively small response to ipratropium becomes relatively more important and may predominate