To elucidate the relationship between captoprilinduced hemodynamic changes and pharmacokinetics, a dose of captopril 37.5 mg was administrated orally to patients with mild essential hypension (HYT: n=13) and normotensive healthy volunteers (NORM: n=11). An attempt was also made to clarify the relationship between humoral factors and hemodynamic changes. After captopril administration, systolic blood pressure (SBP) and diastolic BP (DBP) decreased significantly in HYT and NORM. However, heart rate (HR) did not change in either NORM or HYT. After captopril administration, humoral factors changed as follow: plasma renin activity (PRA) increased significantly in NORM, while insignificant increase of PRA was observed at the maximal SBP fall in HYT; plasma aldosterone concentration decreased significantly in HYT and NORM; plasma norepinephrine concentration (NE) increased significantly in NORM, while there was no statistically significant increase in plasma NE in HYT. No significant difference between the Tmax, Cmax and T1/2 of captopril was found in either HYT or NORM. AUC in HYT was significantly higher than that in NORM. Maximal BP fall was observed at T. after captopril administration in both groups. In HYT, the decreased SBP is associated with the pretreatment PRA. However, no significant correlation was discovered between ΔSBP and Delta;PRA. Captopril also produced a significant decrease in SBP and DBP in both lower-renin HYT and NORM.
