Influence of dosing time of enalapril on the daily variation of pulmonary function: A preliminary study

This study was performed to determine the influence of dosing time of enalapril, an angiotensin-converting enzyme inhibitor, on pulmonary function. Enalapril (10 mg) or placebo was given orally at 10 : 00 and 22 : 00 to eight healthy, nonsmoking, male adults in a randomized, double-blind crossover design. Peak expiratory flow (PEF) was determined at 16 : 00 on day 1 and 04 : 00 and 16 : 00 on day 2. PEF at 04 : 00 was significantly lower than that at 16 : 00 (p < 0.01). Enalapril dosed at 10 : 00 or 22 : 00 did not significantly influence the daily variations of PEF compared to placebo. The daily variation of pulmonary function might not be influenced by a single dosing of enalapril in the morning or evening.