Oral fenoterol versus sustained release theophylline in adult asthmatics

The question regarding the minimal effective oral dose of fenoterol remains unanswered. The present study was undertaken to compare the therapeutic effects of sustained release theophylline and a conventional low dose oral fenoterol in patients with asthma.

A double-blind, double-dummy, randomized, 2-phase, cross-over comparison between sustained-release theophylline (SR-T) and oral fenoterol 2.5 mg 3 times daily in 21 patients with stable bronchial asthma (mean age 51 years) was conducted. Each drug was administered for a 2-week period. All patients qualified with a > or = 15% reversibility in forced expiratory volume in 1 second (FEV1) following 200 micrograms of inhaled salbutamol. Spirometric tests and body plethysmography were done at baseline and at the end of each treatment period. Blood was drawn for routine laboratory analysis and serum theophylline concentration. During each treatment period the patient kept a diary of symptoms and the concurrent use of inhaled salbutamol was recorded.

During SR-T administration trough serum concentrations were 12.9 (1.5) mg/l mean (+/- SEM). SR-theophylline produced greater maximal changes in all parameters measured: FEV1, forced vital capacity, and specific airway resistance from the pretreatment and fenoterol phase, while fenoterol caused significant changes in none of the test variables. Patients showed an overall preference for SR-T over fenoterol (p < 0.05).

Thus, 2.5 mg of fenoterol at 8-hour intervals did not prove to be an effective alternative to sustained release theophylline for management of patients with asthma. An appropriate dosing schedule for fenoterol needs to be redefined.