Effect of high dose spironolactone and chlorthalidone in essential hypertension: relation to plasma renin activity and plasma volume

Efficacy and safety of mineralocorticoid receptor antagonists for the treatment of low-renin hypertension: a systematic review and meta-analysis

Hypertension is the leading risk factor for premature death. The optimal treatment of low-renin hypertension (LRH), present in 30% of hypertensive individuals, is not known. LRH likely reflects a state of excess salt, expanded volume and/or mineralocorticoid receptor (MR) activation. Therefore, targeted treatment with MR antagonists (MRA) may be beneficial. The objective of this systematic review was to assess the efficacy of MRA therapy in LRH. MEDLINE, Embase and Cochrane databases were searched for randomised controlled trials of adults with LRH that compared the efficacy of MRA to placebo or other antihypertensive treatments. Risk of bias was assessed using the Cochrane risk of bias tool. A meta-analysis was performed using a random-effects model to estimate the difference in blood pressure and the certainty of evidence was assessed using the GRADE approach. The protocol is registered on PROSPERO (CRD42022318763). From the 1612 records identified, 17 studies met the inclusion criteria with a total sample size of 1043 participants. Seven studies (n = 345) were assessed as having a high risk of bias. Meta-analysis indicated that MRA reduced systolic blood pressure by -6.8 mmHg (95% confidence interval -9.6 to -4.1) and -4.8 mmHg (95% confidence interval -11.9 to 2.4) compared to angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACEi/ARB) and diuretics. The certainty of the evidence was assessed as moderate and very low, respectively. The findings of this systematic review suggest that MRA is effective in lowering blood pressure in LRH and may be better than ACEi/ARB. Translation to clinical practice is limited by the uncertainty of evidence.

The effects of four months' treatment with spironolactone on systemic blood pressure, cardiac output and plasma renin activity in hypertensive patients

The effect of spironolactone on BP, cardiac output, plasma renin activity and urinary excretion of electrolytes has been studied in 12 hypertensive patients. After 1 month of spironolactone therapy there was a significant decrease in arterial BP. Urinary sodium excretion was significantly decreased and plasma renin activity increased. After four months of spironolactone therapy there was no further decrease in arterial BP. Cardiac output, heart rate and stroke volume were unchanged in the supine position, but the calculated total peripheral vascular resistance (TPVR) was reduced, indicating that the lower BP was mainly a result of dilatation of the resistance vessels. During exercise there was still a significant decrease in arterial BP but this was related to a decrease in both cardiac output and TPVR.

Clinical experience and rationale for angiotensin-converting enzyme inhibition with lisinopril as the initial treatment for hypertension in older patients

Hypertension is a major health problem for patients over 65 years of age. Control of elevated blood pressure reduces cardiovascular morbidity and mortality rates among older hypertensive patients. Increased total peripheral vascular resistance is the primary hemodynamic abnormality in these patients. Initially, diuretics were used alone to lower total peripheral vascular resistance, and thus blood pressure, in older patients. The antihypertensive efficacy of angiotensin-converting enzyme inhibitors has been questioned in this age group, in which low-renin hypertension is common. The latter condition might be thought to favor blood pressure control with diuretics and impair the response to angiotensin-converting enzyme inhibitor therapy. However, recent studies with lisinopril, a new long-acting, nonsulfhydryl angiotensin-converting enzyme inhibitor, indicate that reductions in systolic and diastolic blood pressure in older hypertensive patients receiving either angiotensin-converting enzyme inhibitor or hydrochlorothiazide monotherapy were not significantly different. These data demonstrate that angiotensin-converting enzyme inhibitor monotherapy can effectively lower blood pressure in older hypertensive patients.

Renin classification for diuretic and beta-blocker treatment of black hypertensive patients

Renin classification has been proposed to guide initial treatment of hypertensive patients with diuretics vs beta-blockers. Most previous studies evaluating this issue have utilized patient populations that were white or predominantly white. Black hypertensives have been noted to differ from white hypertensives in several respects. To evaluate the clinical utility of renin classification in black hypertensives, we compared the blood pressure response of low vs normal renin patients during double-blind treatment with either hydrochlorothiazide or beta blocker (metoprolol or oxprenolol). Hydrochlorothiazide a significantly (P less than 0.05-0.01) larger blood pressure fall than beta-blocker, though there was no difference in the response of low vs normal renin patients. Thus, renin classification does not appear to guide initial selection of diuretic vs beta blocker therapy of black hypertensives, and diuretic therapy is more effective.

A comparison between spironolactone and hydrochlorothiazide with and without alpha-methyldopa in the treatment of hypertension

In a single blind crossover trial, spironolactone (50 mg twice a day), and hydrochlorothiazide (50 mg twice a day) were equally effective hypotensive agents in 16 patients with untreated essential hypertension. The addition of alpha-methyldopa (250 mg three times a day) to each agent produced a further significant and equal fall in blood pressure. Spironolactone therapy was assoicated with fewer clinical and biochemical side effects. The hypotensive effect of the diuretics was independent of the renin status of the patients.

Different antihypertensive effect of beta-blocking drugs in low and normal-high renin hypertension

The treatment response to beta-adrenoceptor blocking drugs was compared in two groups of patients with primary (essential) hypertension and different renin levels. Each group consisted of 25 patients and was equally distributed regarding age, severity and stage of hypertension. In the first group (group 1), the mean upright plasma renin activity was 0.8 ng ml-1h-1 (range 0.3 to 1.5) and the patients were considered to have low renin hypertension. In the other group (group 2) the patients had a mean plasma renin activity of 2.1 ng ml-1h-1 (range 1.1 to 5.1) and were considered to have normal to high renin hypertension. In both groups the patients were initially treated with beta-blocking drugs; in group 1 with a beta-blocker corresponding to an average dose of 311 mg propranolol a day for at least eight weeks and in group 2 with propranolol 320 mg a day in a fixed dose for eight weeks. The hypotensive response differed significantly between the two groups (p less than 0.001). In group 1 the pretreatment blood pressure was 197/117 mm Hg supine and 198/120 mm Hg standing. During treatment blood pressure decreased only 5/3 mm Hg supine and 9/5 mm Hg standing. The pretreatment blood pressure in group 2 was 187/114 mm Hg supine and 186/117 mm Hg standing. Beta-blocking therapy reduced blood pressure 36/23 and 34/18 mm Hg, respectively (both p less than 0.001). Pulse rates fell significantly in the two groups, both in the lying and standing positions. In 17 patients with low renin hypertension (group 1), a volume-depleting drug was added (spironolactone, 14 patients; thiazides, 3 patients) and this achieved a marked fall in blood pressure levels of 38/16 mm Hg supine and 37/19 mm Hg standing (both p less than 0.001). These results suggest the following: (1) Most patients with normal to high plasma renin activity respond well to moderate doses of propranolol. (2) Propranolol given in the same doses is almost without antihypertensive effect in patients with low renin hypertension. (3) A volume factor may be operating in patients with low renin hypertension since a hypotensive effect is demonstrated after the addition of volume-depleting drugs. (4) Determination of plasma renin activity with adequate methods can predict the treatment response to hypotensive agents.

Controlled treatment of primary hypertension with propranolol and spironolactone. A crossover study with special reference to initial plasma renin activity

Twenty-seven patients with hypertension were randomly allocated to a 10 month crossover study. Treatment consisted of spironolactone (200 mg/day for 2 months), propranolol (320 mg/day for 2 months) and combined administration of both drugs at half the dosage. Between treatment periods placebo was given for 2 months. Fourteen patients were previously untreated. The average pretreatment blood pressure for the entire group was 188/114 +/- 16/7(mean +/- standard deviation) mm Hg supine and 188/118 +/- 20/9 mm Hg standing. Both spironolactone and propranolol reduced blood pressure significantly in both the supine and standing positions. Upright plasma renin activity was determined by radioimmunoassay of angiotensin I. The average initial level was 1.9 +/- 1.2 (range 0.4 to 5.0) ng/ml/hr. There was a close correlation between plasma renin activity and the effects of the drugs: With increasing renin level the response to propranolol was better whereas the opposite was true for spironolactone. The combination of spironolactone and propranolol decreased the blood pressure still further in the supine and standing positions, irrespective of initial plasma renin activity. All patients achieved a normal supine pressure. Blood pressure and plasma renin activity returned toward pretreatment values during placebo administration. It is concluded that pretreatment levels of plasma renin activity can predict the antihypertensive response to propranolol and spironolactone. The combination of the two drugs, which have different modes of action, will effectively reduce blood pressure in hypertension. The results support the concept that the renin-angiotensin-aldo-sterone system may be involved in primary hypertension.

Renin concentrations and effects of propranolol and spironolactone in patients with hypertension

In a crossover study 32 patients with hypertension were randomly allocated to treatment with spironolactone 200 mg/day for two months, propranolol 320 mg/day for two months, and a combination of both drugs at half the dose. Between the treatments placebo was given for two months. Both spironolactone and propranolol lowered the blood pressure significantly in both positions. The initial plasma renin activity (PRA) levels ranged from 0-4 to 5-0 mug angiotensin I l-1 h-1, and there was a close correlation between these levels and the effects of the drugs: with increasing PRA the response to propranolol was better while the opposite was true for spironolactone. Spironolactone reduced the blood pressure more at eight than at four weeks, while no such difference could be shown for propranolol. Spironolactone and propranolol together decreased the blood pressure still further irrespective of the initial PRA. All patients achieved a normal supine blood pressure.