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 expiratory volume in one second (FEV1), and forced vital capacity (FVC). Thirty minutes after a theoretically maximally bronchodilating dose of salbutamol (400 microgram) or ipratropium (80 microgram), second doses freque...
