Dose and 24-hour blood pressure control of enalapril in hypertensive patients

Abstract

To compare the 24-hour antihypertensiveeffects between different doses of enalapril in mild and moderatehypertensive patients by administered the drug once daily and monitoredblood pressure by 24-hour ambulatory blood pressure monitoring (ABPM)machine. The study was achieved in twenty-one mild to moderate primaryhypertensive patients in out-patients department at PhramongkutklaoHospital. The study consisted of a 2-week placebo run-in period or onplacebo for at least 5 t(,1/2) to washout of any antihypertensive drug ifpreviously taken. The patients with seated systolic blood pressure (SBP)140-179 mmHg or diastolic blood pressure (DBP) 90-110 mmHg and 24-hour meanambulatory DBP (+,ณ) 85 mmHg after placebo were allocated into the study. Mildhypertensive patients were prescribed to start with 5 mg, while themoderate hypertensive patients were started with 10 mg of enalapril oncedaily. After 4 weeks the dosages were increased from 5 to 10 mg or from 10to 20 mg for another 4 weeks if the patients did not achieve the targetoffice BP [office > 90 mmHg] while the doses were decreased froms 5 to 2.5mg and 10 to 5 mg if the patients were normalize with the initial doses.The office BP and the ambulatory blood pressure were monitored at the endof each period. After 4 weeks of treatment period, It was found that seven of mildand nine of moderate hypertensive patients required titration doses from 5to 10 mg and 10 to 20 mg of enalapril since their office DBPremained(+,ณ)90 mmHg. 24 hour BP ,day-time and night-time BP were allsignificantly reduced from baseline with 5-20 mg per day of enalapriladministration (p< 0.05). Enalapril in the dose of 5 mg per day showed nostatistically significant reduction in office BP (p=1.000). The mean rateof BP reduction per one mg of enalapril was no statistically significantlydifferent between mild and moderate hypertensive patients. The rate wasapproximate 1-2 mmHg for SBP and 0.7 mmHg for DBP in both mild and moderatehypertensive patients. There were no relationship between rate of BPreduction and patient characteristics e.g. age, sex, although mildhypertensive patients and pretreatment BP was slightly higher than inmoderate hypertensive patients. Calculation of BP loads and AUC found thathigher dose resulted in higher reduction in BP loads and AUC above normalrange but these reduction were not linearly proportion with doses. Mostly,enalapril would reduced BP to the extent of 0-20 % below the baseline BP ofthe patients, very few percentage of the BP were reduced beyond the extremeof > 30 %. T : P ratio was varied among individual patients with theaverage around 40-60% and was likely to increase when treated with higherdose of enalapril. The antihypertensive effect was produced without thereflex tachycardia or other intolerance effects.