Effect of nifedipine and theophylline in asthma

The effect of nifedipine, 10 mg po q.i.d. for 2 weeks, was studied in a randomized, double-blind, crossover trial in nine patients with asthma receiving theophylline. Nifedipine did not significantly affect the mean (± SD) morning peak expiratory flow rate (PEFR; 336 ± 130 L/min for drug vs. 349 ± 92 L/min for placebo), evening PEFR (393 ± 69 L/min for drug vs. 367 ± 66 L/min for placebo), symptom score (27.4% ± 22.9% for drug vs. 33.8% ± 26.4% for placebo), or the number of albuterol inhalations per day (5.8 ± 3.5 for drug vs. 6.2 ± 4.1 for placebo). Furthermore, there was no change in PEFR 30, 60, or 120 minutes after nifedipine dosing. Nifedipine did not significantly affect the steady-state serum theophylline trough levels (9.1 ± 2.2 mg/ml for drug vs. 10.2 ± 1.9 μg/ml for placebo) or the theophylline pharmacokinetic parameters, such as the elimination t _{1 2} peak serum concentration, time to peak, and AUC(0-24). We conclude that nifedipine has little, if any, effect on the clinical status, PEFR, or theophylline serum levels in patients with asthma who receive theophylline.