Bronchodilator effect and serum theophylline level after combined treatment with fenoterol and theophylline in reversible chronic airflow obstruction.

Sustained-release theophylline 10.1 mg/kg b.d. was given with placebo of fenoterol 2.5 mg t.d.s. to 12 patients with chronic airway obstruction. Fenoterol did not significantly affect the steady state serum theophylline trough level (11.84 micrograms/ml for fenoterol vs 11.10 micrograms/ml for placebo). Addition of fenoterol produced no further increase in spirometric function nor in clinical status.