Captopril before and after spironolactone therapy in primary aldosteronism. Pathogenetic and therapeutical aspects

A review of the medical treatment of primary aldosteronism

PURPOSE

Use of the aldosterone-to-renin ratio (ARR) has suggested that at least one in 10 hypertensive subjects have primary aldosteronism (PA). There is thus a timely need to review the literature for effective drug therapies and to speculate on other therapeutic options by taking into account recent advances in understanding of the PA disease pathophysiological process.

DATA SOURCE

A MEDLINE and EMBASE search of all articles published from the start of the databases until July 1999 and reviews of the bibliographies of textbooks.

STUDY SELECTION

Primary research articles on the medical treatment of PA with emphasis on diagnosis, treatment option, drug dosage, therapeutic response and adverse drug effect.

DATA EXTRACTION

Study design and quality were assessed. Relevant data on diagnostic methodology, drug usage and response were analysed and compared.

DATA SYNTHESIS

A select number of subjects with aldosterone-producing adenoma (APA) can be expected to respond well to surgical treatment For the majority of PA cases especially subjects with idiopathic hyperaldosteronism (IHA), long-term medical treatment is now safe and feasible although no randomized controlled trials have been carried out to date. The best therapeutic response is obtained by directly antagonizing aldosterone at the receptor level using medium to low dose spironolactone and this response can be predicted by a raised ARR. The response to other potassium-sparing diuretics and calcium channel blockers are modest. IHA responds better than angiotensin II-unresponsive APA to angiotensin converting enzyme inhibitors and this may also be true with angiotensin II receptor blockers. The discovery of the aldosterone synthase gene opens up the possibility for gene therapy.

CONCLUSION

The diagnosis of PA allows appropriate management with resultant blood pressure control in many hypertensive subjects who otherwise have resistant hypertension despite multiple drug therapy.

Therapeutic value of calcium antagonists in autonomous hyperaldosteronism

The chronic effect of the calcium antagonist nitrendipine was investigated on blood pressure (BP), plasma aldosterone concentration (PAC), plasma renin activity (PRA), and serum potassium in six patients with primary aldosteronism, either due to an (unilateral) aldosterone-producing adenoma (APA; n = 3; age, 44 +/- 4 years; PAC, 312 +/- 96 pg/ml; PRA, less than 0.1 ng/l.h; serum potassium, 2.8 +/- 0.3 mmol/l) or to bilateral idiopathic hyperaldosteronism (IHA; n = 3; age, 49 +/- 1 years; PAC, 212 +/- 32 pg/ml; PRA, 0.1 +/- 0.1 ng/l.h; serum potassium, 3.3 +/- 0.2 mmol/l). After withdrawal of antihypertensive medications at least 3 weeks prior to the study, nitrendipine was given orally in a daily dosage of 40 to 60 mg. BP, PAC, PRA, and serum potassium were determined before (see data above) and after 4 weeks of nitrendipine therapy. After 4 weeks, BP was significantly reduced (178 +/- 10 to 165 +/- 6 mmHg systolic, 109 +/- 7 to 101 +/- 6 mmHg diastolic) in three patients with APA and in two with IHA. No significant changes of PAC, PRA, and serum potassium were observed in these patients. However, one patient with clinical characteristics of IHA and a long-term history of diuretic therapy showed a complete normalization of BP, PAC, PRA, and serum potassium, suggesting that the etiology of autonomous hyperaldosteronism in this patient might differ from typical primary aldosteronism. From these findings we conclude that calcium antagonists may be helpful in lowering BP in those patients with primary aldosteronism who develop intolerable side effects under treatment with spironolactone or trilostane.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy, tolerance and hormonal effects of a new oral angiotensin converting enzyme inhibitor, ramipril (HOE 498), in mild to moderate primary hypertension

The immediate (0 to 24 hours) and long-term (4 weeks) hypotensive effects of a new long-acting angiotensin converting enzyme inhibitor, ramipril (HOE 498), as well as adverse effects and tolerance, were evaluated in 34 patients with primary hypertension. Further, effects on serum and urinary aldosterone and circulating angiotensin II concentrations were measured. After short- and long-term administration of 5 or 10 mg of ramipril, the mean blood pressure was significantly lowered compared with placebo. The mean maximum decrease in blood pressure was noted 4 to 8 hours after administration of ramipril once daily. Sustained blood pressure reduction was achieved after 4 weeks of treatment. Serum concentrations of aldosterone and plasma levels of circulating angiotensin II were reduced for up to 12 hours after drug intake, and tended to return to pretreatment levels at 24 hours. Serum angiotensin converting enzyme activity was markedly suppressed for more than 24 hours after a single dose of 5 or 10 mg ramipril. No subjective or objective adverse effects were noted, and the tolerance to the drug was very good.

[Results of a 5-year study with captopril in patients with severe therapy-resistant hypertension]

The angiotensin converting enzyme (ACE) inhibitor captopril proved to be an effective antihypertensive drug during a 5-year follow-up study of patients with severe hypertension who had been resistant to a triple-drug regimen. Of the 42 patients, 41 had to be treated additionally with diuretics. Because of hypokalemia, potassium supplements were necessary in 26 patients, despite the use of "potassium-saving" diuretics in 12 patients. Blood pressure was controlled sufficiently in 3/4 of the patients during the 5 years. Patients with a large elevation in plasma renin activity showed the best response to the treatment. Six patients died during the 5 years. Therapy had to be stopped in 11 patients because of complications. The following complications and adverse effects were observed: cerebral ischemia (n = 10), vertigo and orthostasis (10), exanthema (9), hypogeusia (7), circulatory failure (7), myocardial infarction (6), and scintigraphically demonstrable decrease of renal perfusion (5). One patient with bilateral renal artery stenosis suffered from acute renal failure, which was reversible after withdrawal of captopril. Significant changes of red and white blood cell counts, transaminases, lipids, urine protein excretion, and heart rate were not observed.

Is single oral administration of captopril beneficial in screening for primary aldosteronism?

Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were measured in 19 cases with primary aldosteronism (PA) and in 72 with essential hypertension (EHT) to differentiate the two disorders during the following conditions on normal salt diet: after overnight recumbency (basal state) and 2 hours after oral administration of 25 mg of captopril. Screening criteria were determined so that all PA patients were diagnosed as positive, and their specificities were compared with those of other conventional screening methods for PA. After captopril administration, the specificity of a criterion based on a combination of PAC and PAC/PRA ratio was 93% and positive predictive value was 79%. This criterion was superior to blood pressure response to angiotension II analog infusion, PRA on salt depletion, and to PAC on salt loading. However, higher specificity (97%) and positive predictive value (90%) were obtained from a criterion based on a combination of basal PAC and PAC/PRA ratio. Therefore, the use of a combination criterion based on PAC and PAC/PRA ratio at basal state rather than after captopril administration may give a satisfactory result in the screening for PA.