A randomised comparative trial of nicardipine versus amiloride and hydrochlorothiazide in mild to moderate hypertension. A report from the General Practitioner Hypertension Study Group

In 1984 the General Practitioner Hypertension Study Group undertook a rescreening of their patient population, looking for patients who still had untreated mild to moderate essential hypertension. Suitable patients were entered into a clinical trial comparing the safety and efficacy of nicardipine (a calcium antagonist) and amiloride + hydrochlorothiazide (HCTZ) (moduretic). The study included one year of long-term follow-up. Both drugs significantly lowered BP in both the short and long term. Numbers and percentages of patients from each group reporting adverse experiences were similar in the short term, but in the long term the frequency of adverse event reporting was much lower with nicardipine treatment than with amiloride + HCTZ treatment (2/10 versus 9/17). Treatment with amiloride + HCTZ led to elevations in serum levels of cholesterol, uric acid and urea, which were maintained at one year, whilst no abnormalities in blood biochemistry were seen in patients treated with nicardipine. In conclusion we have found that nicardipine compares very favourably with amiloride + HCTZ in the treatment of mild to moderate hypertensive patients.

Maintenance of potassium balance during long-term diuretic therapy in chronic heart failure patients with thiazide-induced hypokalemia: comparison of potassium supplementation with potassium chloride and potassium-sparing agents, amiloride and triamterene

The relative efficacy of potassium chloride, amiloride and triamterene in maintaining potassium and magnesium balance was evaluated in 23 hypokalemic (S-K less than or equal to 3.5 mmol/l) patients with chronic heart failure receiving diuretic therapy. Amiloride and triamterene were administered in a randomized, crossover manner, followed by potassium chloride in an open manner. During a 5-month treatment with hydrochlorothiazide 50 mg twice/day, potassium chloride 1 g twice/day was not as effective as amiloride 5 mg or triamterene 75 mg twice/day in maintaining serum potassium and magnesium and total-body potassium, while amiloride and triamterene seemed to be equally effective. During all three supplementations, a decrease in serum potassium to a hypokalemic level was observed in some patients. The need for higher doses of potassium chloride, amiloride and triamterene was clearly concentrated to the same patients, and correction was easily reached by increasing the respective doses.

[Hydrochlorothiazide-induced lung edema with shock]

We report the case of a 74-year-old woman who developed pulmonary edema and shock shortly after ingestion of one tablet of hydrochlorothiazide/amiloride. The clinical findings and course of the disease were characteristic of hydrochlorothiazide-induced pulmonary edema. 14 similar case are reported in the literature. Attention is drawn to this rare but dangerous side effect of a frequently used diuretic.

An open study to compare the efficacy and tolerability of two diuretic combinations, frusemide plus amiloride and hydrochlorothiazide plus amiloride, in patients with mild to moderate essential hypertension

Forty-four patients with mild to moderate essential hypertension were entered in an open study to compare the efficacy and tolerability of the two diuretic combinations, frusemide (40 mg) plus amiloride (5 mg) and hydrochlorothiazide (50 mg) plus amiloride (5 mg), as first-line treatment. After a 2-week run-in period when no antihypertensive medication was given, patients were randomized to receive one or other combination at a dose of 1 tablet daily for 2 weeks. Patients either remained on this regimen for a further 8 weeks or, if their blood pressure was not controlled, dosage was increased to 2 tablets daily. In the latter case, patients were re-assessed after 2 weeks, and those who showed a positive response remained in the study for 8 additional weeks. In the 36 patients assessed (18 in each group), both treatments were found to reduce blood pressure effectively in a high percentage of patients treated. Hydrochlorothiazide/amiloride, however, caused a significant reduction in both plasma potassium and sodium levels whereas frusemide/amiloride did not. More adverse events were reported by patients taking frusemide/amiloride, but the majority of these were trivial.

Bisoprolol versus hydrochlorothiazide plus amiloride in essential hypertension, a randomized double-blind study

Beta blocker monotherapy is often considered to be inadequate in essential hypertension. It was the aim of this study to compare the antihypertensive activity of the new betablocker bisoprolol with the diuretic combination: hydrochlorothiazide plus amiloride. Forty hypertensive patients (DBP 95-120 mmHg) were enrolled in the study, of which 34 were evaluable for efficacy. The patients were, under double-blind conditions, randomly allocated to receive 10 mg bisoprolol (B) or 50 mg hydrochlorothiazide plus 5 mg amiloride (HA) as single daily doses for 30 days. Patients whose DBP had been normalized (less than or equal to 90 mmHg) after 30 days (D 30) continued the monotherapy for another 30 days. Patients whose DBP remained over 90 mmHg were, under single-blind conditions, kept on their initial treatment but received in addition the alternative drug for another 30 days (D 60). Blood pressure measurements were performed 24 hours after drug intake. The two groups comprising 17 patients each were comparable with regard to the patients' characteristics and baseline blood pressure values. After 30 days of treatment supine SBP, DBP and HR were significantly more reduced with B than with HA. The mean reduction of DBP was 16.8 +/- 8.0 mmHg with B and 8.4 +/- 6.4 mmHg with HA (P less than 0.002). After 30 days of monotherapy, blood pressure was within the normal range in 15/17 (88.2%) patients treated with B but in only 4/17 (23.5%) patients treated with HA (B vs HA: P less than 0.001). In the B group, there was a further slight decrease in SBP, DBP and HR during the second 30 day period.(ABSTRACT TRUNCATED AT 250 WORDS)

Atenolol vs. amiloride-hydrochlorothiazide in the treatment of mild to moderate hypertension: a double-blind, crossover, placebo-controlled study

The antihypertensive effect of atenolol 100 mg was compared to that of amiloride HCl 5 mg + hydrochlorothiazide 50 mg (AHCZ) in a double-blind, crossover, placebo-controlled study of 128 patients. Both drugs were given once daily. Atenolol produced a significant decline in lying, standing, and postexercise blood pressure and pulse rate values. The corresponding values on AHCZ were not significantly different from placebo. Both the beta-blocking agent and the thiazide diuretic with amiloride were relatively well tolerated. More than half of all adverse effects were nonspecific and also observed in patients on placebo. In the population studied, atenolol proved to be a superior antihypertensive agent to AHCZ.

A comparative study of the pharmacokinetics and pharmacodynamics of atenolol, hydrochlorothiazide and amiloride in normal young and elderly subjects and elderly hypertensive patients

Six normal young and six normal elderly volunteers and six elderly hypertensive patients took part in an acute and chronic dose study of a combination capsule containing atenolol (50 mg), hydrochlorothiazide (25 mg) and amiloride (2.5 mg) designed for the treatment of hypertension. No difference in any of the drug pharmacokinetic parameters could be detected between the hypertensives and the normal elderly subjects. The bio-availability and the 24-h blood concentrations of all three drugs, half-life of atenolol and amiloride and the peak concentration of hydrochlorothiazide was significantly greater in the elderly. The 24-h blood concentrations of atenolol and hydrochlorothiazide did not alter with chronic dosing, but amiloride concentrations were significantly higher at this time in all groups. A significant fall in the blood pressure was observed in the hypertensive group. Heart rate fell more in the normal and hypertensive elderly subjects than in the young. The combination has shown to be an effective and well tolerated antihypertensive in the elderly patient with a 24-h duration of action.

Felodipine versus Moduretic. A double-blind parallel-group multicentre study

In a double-blind parallel-group study 133 patients with mild to moderate essential hypertension were randomised to felodipine 5mg twice daily or Moduretic mite every morning after a run-in placebo period of 1 to 2 weeks. All previous antihypertensive therapy was withdrawn at the start of the run-in period. After 4 weeks the dose of felodipine was increased to 10mg twice daily, and Moduretic mite was replaced by Moduretic in patients with a diastolic blood pressure of greater than 80mm Hg. On the low dose, the supine blood pressure on felodipine was reduced by 24/14mm Hg from 174/105mm Hg, and on Moduretic mite by 19/11mm Hg from 171/103mm Hg. After the increase in dosage blood pressure was lowered further. There was no statistically significant difference in blood pressure reduction between the 2 groups. Severe adverse drug experiences (ADEs) were few and equally distributed. However, more felodipine patients were withdrawn because of ADEs. Potassium levels decreased and uric acid levels increased significantly in the Moduretic group.

Clinical efficacy and safety of long-term diuretic treatment in renal parenchymal hypertension

In 48 patients with early stage renal disease and mild to moderate hypertension, control of high blood pressure and metabolic alterations during long-term diuretic treatment (mean duration, 71 months) were assessed. Compared to the untreated state, administration of thiazide-potassium sparing diuretics, a single table per day, supplemented by dietary sodium restriction, led to normalization of high blood pressure. Renal function was preserved. Gross abnormalities in electrolyte metabolism did not occur. Deterioration of glucose tolerance was noted in 3 patients. Preexisting hyperlipidemia was aggravated by the diuretics in men and postmenopausal women, but premenopausal women were protected. Long-term diuretic treatment was well tolerated, and caused remarkably few significant untoward reactions. The unfavorable metabolic response to diuretic treatment may, however, cancel part of the potential benefit of blood pressure control in certain patients. During long-term diuretic treatment of renal patients, attention should be given to monitoring of metabolic parameters and the introduction of specific dietary treatment may become the cornerstone of patient management.

Arrhythmogenic potential of diuretic induced hypokalaemia in patients with mild hypertension and ischaemic heart disease

In view of evidence suggesting an association of mild hypokalaemia with cardiac arrhythmia, the arrhythmogenic potentials of potassium losing and potassium sparing diuretic treatments were compared in a controlled prospective crossover study of 10 patients with mild hypertension and ischaemic heart disease. Mean (SEM) plasma potassium was 4.3(0.06) mmol/l and 3.3(0.07) mmol/l after potassium sparing and potassium losing treatments respectively. Blood pressure and volume depletion as assessed by weight change, plasma renin activity, and noradrenaline concentrations did not differ significantly in the two treatment periods. The potassium losing treatment phase was associated with an increased frequency of ventricular extrasystoles, a higher Lown grading during ambulatory electrocardiographic monitoring, prolonged duration and decreased phase 0 velocity of the monophasic action potential, a prolonged ventricular effective refractory period, and increased myocardial electrical instability as assessed by programmed ventricular stimulation. It is concluded that minor changes in plasma potassium concentration are associated with increased ventricular electrical instability in patients with ischaemic heart disease. Mild hypokalaemia in such patients may predispose to life threatening arrhythmias and should be avoided.

Renal failure with potassium-sparing diuretics

In one year 19 patients aged 73 SD 8 yr were referred with renal failure (plasma creatinine 0.14-0.52 mmol/l; urea 7.9-39.5 mmol/l; potassium 2.9-6.1 mmol/l, who were taking amiloride/hydrochlorothiazide (ten), amiloride alone (one) or triamterene/hydrochlorothiazide (eight). Six patients were taking other diuretics. Sixteen patients were being treated for hypertension and three for fluid retention; five hypertensive patients were also taking non-steroidal anti-inflammatory drugs (NSAID). Four patients were hypokalaemic, three were volume-depleted. All potassium-sparing diuretics and NSAID were stopped (four required another diuretic). Six-100 days later renal function was improved in 17 patients, unchanged in one and one patient had died of uraemia. Blood pressure was satisfactory on no therapy in 11 patients and two normotensive patients were oedema-free. In elderly patients with renal impairment potassium-sparing diuretics may cause renal failure, sometimes secondary to hypovolaemia, and NSAID may potentiate the effect.

Hydrochlorothiazide-amiloride versus hydrochlorothiazide alone for essential hypertension: effects on blood pressure and serum potassium level

In a double-blind randomized controlled trial the effects on the blood pressure and the serum potassium concentration of hydrochlorothiazide-amiloride hydrochloride (Moduret) and hydrochlorothiazide alone were compared in 266 adults who were normokalemic and had a diastolic blood pressure greater than 95 mm Hg at the time of entry into the study. The mean ages (52.2 and 53.8 years) and the proportions of men (66% and 56%) in the groups given the combination drug and hydrochlorothiazide alone respectively were similar. In the group given the combination drug the mean blood pressure, measured while the patients were supine, and the mean serum potassium level fell significantly, from 156/99 to 138/88 mm Hg and from 4.23 to 3.91 mmol/L, after 8 weeks of treatment. In the other group both measures also fell significantly, the blood pressure from 157/99 to 138/87 mm Hg and the potassium level from 4.16 to 3.69 mmol/L. The proportions of patients in the two groups with hypokalemia (14% and 29% respectively), defined as a serum potassium level below 3.5 mmol/L, differed significantly (p = 0.0026), whereas the proportions with a potassium level exceeding 4.5 mmol/L (4.5% and 3.9% respectively) were similar. Thus, the combination drug reduced the blood pressure to the same extent as hydrochlorothiazide alone but significantly less often caused hypokalemia. In light of growing concerns about the cardiovascular complications of hypokalemia, hydrochlorothiazide-amiloride appears preferable to hydrochlorothiazide alone for the treatment of some patients with hypertension.

Limitation on the use of amiloride in early renal failure

The effect of a single oral dose of 10 mg amiloride was studied on urinary excretion of Na+, K+, Ca++ and Mg++ in healthy subjects and in patients with varying degrees of renal impairment. Amiloride produced a moderate diuresis and sodium excretion, and a slight calciuresis. Urinary excretion of potassium was significantly reduced as compared to the controls. Despite its diuretic and natriuretic effects, amiloride did not change the excretion of Mg++ as compared to the pretreatment period. When the creatinine clearance was below 50 ml/min, the net excretion of Na+ and Ca++ was drastically reduced. However, K+ retention and neutrality of Mg++ excretion were maintained down to end-stage renal disease. In the healthy volunteers the mean elimination half-life of amiloride was 20 h, and it rose to about 100 h in end-stage renal disease. This was because about 3/4 of native amiloride was eliminated through the kidney. Nonrenal elimination of amiloride was calculated to amount to only 1/4 of the total elimination. Therefore, the anticaliuretic amiloride is a valuable comedication in subjects with normal kidney function to prevent K+ and Mg++ loss. However, its use is hazardous if plasma creatinine is raised.

Metabolic consequences of long-term thiazide-based antihypertensive treatment of renal hypertension

In 72 outpatients with early stage disease and mild to moderate hypertension, metabolic parameters were evaluated before and during 6 years of treatment with two different thiazide diuretic-based antihypertensive therapy regimens. Compared to the untreated state, chronic diuretic treatment caused a persisting increase in serum lipids in men or postmenopausal women. The high incidence of electrocardiographic abnormalities indicative of ischemic changes suggests a possible negative influence of diuretic-induced metabolic alterations on coronary heart disease in these patients.