ENARIL is an angiotensin converting enzyme (ACE) inhibitor. The effect of a dose will gradually take place within one hour and will usually stay for 24 hours, daily dosage may given in one or two single administrations. Enalapril is a prodrug and will be transformed to enalaprilat which is active by liver. ENARIL can reduce blood pressure in normal and hypertensive person by reducing peripheral vascular resistant but has no effect to heart rate. For the patient without congestive heart failure, ENARIL has no effect or little effect to cardiac output and does not interfere renal blood flow or glomerular filtration rate.