Granulomatous interstitial nephritis associated with hydrochlorothiazide/amiloride

A 74-year-old woman developed acute renal failure and granulomatous interstitial nephritis associated with hydrochlorothiazide/amiloride. On stopping the drug the renal function improved, but not significantly. Around 20 months after prednisone administration, the renal function had stabilized, with a moderate degree of renal insufficiency. The case is discussed, and some aspects of acute interstitial nephritis induced by diuretics are briefly reviewed.

Amiloride-quinidine interaction: adverse outcomes

OBJECTIVES

Previous studies have reported beneficial antiarrhythmic effects when selected drugs were combined. The purpose of this study was to assess whether a favorable interaction would occur with amiloride and quinidine.

DESIGN

The antiarrhythmic and electrophysiologic effects of quinidine alone and in combination with amiloride were assessed in 10 patients with inducible sustained ventricular tachycardia. Parallel electrophysiologic studies assessed this drug combination in guinea pig papillary muscle.

RESULTS

None of the patients had adverse effects during quinidine monotherapy. However, seven of 10 patients had adverse responses to the combination treatment: three patients had suppression of inducible ventricular tachycardia during quinidine monotherapy but had sustained ventricular tachycardia induced during combination treatment; three other patients had somatic side effects that resulted in discontinuation of the combination therapy but were absent during quinidine monotherapy; and one patient had 12 episodes of sustained ventricular tachycardia during this combination therapy. The patient had no such response during monotherapy. Surface QRS duration was significantly more prolonged during combination therapy than during monotherapy. Parallel electrophysiologic effects assessed this drug combination in guinea pig papillary muscle. The combination of amiloride (1 mumol/L) and quinidine (10 mumol/L) synergistically decreased the maximum rate of rise of phase 0 of the action potential (Vmax) (43 +/- 12 V/sec) compared with quinidine alone (24 +/- 9 V/sec) because of a greater degree of tonic block of Vmax (14% +/- 6%) as compared to quinidine alone (3% +/- 3%) with no significant change in action potential duration.

CONCLUSIONS

Amiloride exaggerates the effects of quinidine on QRS duration in patients and on Vmax during in vitro study, which implies that the proarrhythmic effect of the combination of amiloride and quinidine may be associated with synergistic increase in sodium channel blockade.

Antihypertensive efficacy and tolerability of different drug regimens in isolated systolic hypertension in the elderly

The pharmacological treatment, mainly based on diuretics, of isolated systolic hypertension (ISH) has recently been shown to reduce the risk of stroke and coronary heart disease in the elderly. The purpose of this study was to compare the antihypertensive effect and tolerability of different drug regimens in elderly subjects with ISH (systolic blood pressure--SBP-- > or = 160 mmHg and diastolic blood pressure--DBP-- < 90 mmHg). A multicentre, randomized, controlled open trial was planned in the general practice setting. Four widely used treatment schedules were tested: hydrochlorothiazide 25 mg plus amiloride 2.5 mg (H+Am), nifedipine slow release 20 mg (N), atenolol 50 mg (At) and atenolol 25 mg plus chlorthalidone 6.25 mg (At+C). After a baseline evaluation, 308 patients (76.3% female, mean age 75.3 +/- 7.1 years) were randomized and followed up for 6 months. After 3 months the drug dosage was doubled if the systolic blood pressure goal (SBP < 160 mmHg and SBP reduction of at least 20 mmHg) had not been reached. Ninety-four subjects (30.5%) presented contraindications to beta-blockers. At the 3rd- and 6th-month visits all treatment groups, except At, showed a significant reduction in SBP compared to the control group; DBP showed no significant reduction in any group at any time. At the end of the follow-up the percentage of hypertensives who had reached the BP goal was 14.6% in the control group, 52.9% in H+Am, 54.8% in N, 28.6% in At and 52.2% in At+C.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of moduretic on plasma lipid and lipoprotein levels in hypertensive African patients

Twenty patients with essential hypertension aged 39-70 years, underwent 20 weeks (short-term) and 30 weeks (long-term) lipid and lipoprotein assessment following moduretic (combination of hydrochlorothiazide and amloride) therapy. Moduretic caused adverse alterations in plasma lipid and lipoprotein concentrations at 20 weeks, characterized by increases in total cholesterol (TC) (9-23%), low-density lipoprotein-cholesterol (LDL-C) (18-42%), Triglycerides (TG) (12-26%) and LDL-C/HDL-C (36-92%), as well as decreases in high density lipoprotein-cholesterol (HDL-C) (-14 to -26%) and HDL-C/TC (-23 to -39%). For 12 patients who were continued on the same therapy for the longer period of 30 weeks, the adverse effects were less pronounced when compared with the short-term effects. The increases in TC (9.6%), in LDL-C (21%), and in LDL-C/HDL-C (48%), and the decreases in the mean HDL-C (-20%), and in HDL-C/TC (-25%), were all significant. In contrast, the slight increase in TG noted during the long-term moduretic therapy was not significant. Our data suggest that moduretic therapy induces altered lipid-lipoprotein patterns in hypertensive patients. However, the possible influence of baseline cholesterol concentration and the duration of therapy, may be important factors in the lipid response to moduretic therapy.

A study of plasma sodium levels in elderly people taking amiloride or triamterene in combination with hydrochlorothiazide

This study was performed to compare the effect of one month's treatment with hydrochlorothiazide (25 mg) in combination with either amiloride (2.5 mg) or triamterene (50 mg) on plasma sodium levels in elderly people in institutional care. Fifty residents of NHS nursing or social service residential care established on diuretics for congestive cardiac failure and aged 64 years or over were recruited. Forty-one patients were included in the final data analysis. Patients on hydrochlorothiazide/amiloride had a significantly lower plasma sodium (137 vs 139 mmol/l, 95% confidence interval for difference between medians 0-2 mmol/l) than those on hydrochlorthiazide/triamterene (P = 0.01). In equivalent potassium-retaining doses, amiloride is associated with significantly lower plasma sodium levels than triamterene, when given in combination with hydrochlorothiazide in elderly patients with congestive cardiac failure. This finding adds weight to uncontrolled observations implicating thiazide/amiloride diuretic combinations in causing serious hyponatraemia. This danger, although uncommon, should perhaps influence prescribing habits in an at-risk population.

[Amiloride inhalation therapy in mucoviscidosis]

The defective regulation of the secretory chloride channel and the accelerated rate of sodium absorption in the airway epithelia of patients with cystic fibrosis (CF) contribute to the dehydration of airway secretions which is responsible for secondary damage in the respiratory tract. The sodium-blocker amiloride inhibits sodium absorption depending on the dosage of the drug. This effect is documented by means of measuring transepithelial potential difference which is decreased following to inhalative amiloride administration in CF patients. Clinical long term efficiency has been shown to be probable, but has to be confirmed. Investigation in this field is difficult, because there are some other important factors which influence viscosity of mucus. The use of amiloride can best be evaluated, if it is given immediately after birth. However, the answer to some important questions has to be found before.

A comparison of the potassium and magnesium-sparing properties of amiloride and spironolactone in diuretic-treated normal subjects

1. The relative potencies of amiloride (5 and 20 mg) and spironolactone (25 and 100 mg) for plasma and erythrocyte electrolytes were investigated in a double-blind, randomised, balanced, crossover study in 12 normal men treated concomitantly with hydrochlorothiazide 100 mg daily for 1 week. 2. Participants satisfied an a priori requirement for a fall in plasma potassium concentration of at least 0.5 mmol l-1 after 7 days of treatment with hydrochlorothiazide alone. 3. After hydrochlorothiazide alone, plasma potassium and sodium concentrations fell (P < 0.001). There were associated reductions in erythrocyte sodium (P < 0.01). Plasma magnesium concentration did not change, although erythrocyte magnesium decreased (P < 0.001). 4. Both amiloride and spironolactone attenuated the thiazide-induced fall in plasma potassium (relative potency, amiloride:spironolactone 10:1, 95% confidence interval 6.3-16.2:1). Amiloride but not spironolactone was associated with a dose-related increase in plasma magnesium; a relative potency estimation was precluded. There was little evidence of influences of amiloride or spironolactone on erythrocyte electrolytes. 5. On a weight basis, amiloride is ten times more potent than spironolactone as a potassium-sparing agent in diuretic-treated subjects but neither agent had major effects on erythrocyte potassium. The drugs may have divergent actions on magnesium handling; hydrochlorothiazide alone had no influence on plasma magnesium.

Muscular paralysis and ventilatory failure caused by hyperkalaemia

We report the history of a diabetic man presenting with hyperkalaemia and rapidly progressing muscular paralysis with severe respiratory embarrassment. His symptoms resolved rapidly with reduction of the serum potassium concentration. Similar cases have been reported previously but this is a problem that few will have encountered and is a diagnosis which should not be overlooked before artificial ventilation is commenced.

Impaired salivary gland function after radiotherapy compounded by commonly prescribed medications

Impaired salivary gland function can be a major cause of late morbidity following the treatment of head and neck cancer with radiotherapy. A large number of commonly prescribed medications can also reduce salivary gland function. We report three patients with already impaired salivary gland function following successful radiotherapy in whom additional prescribed medication led to an increased reduction in salivary flow, thus further impairing the quality of life of these patients. Stopping the medication resulted in subjective and objective improvement in salivary gland function.

Preventable sudden death in patients receiving angiotensin converting enzyme inhibitors and loop/potassium sparing diuretic combinations

Angiotensin-converting-enzyme inhibitors are frequently used in conjunction with diuretics in the treatment of congestive cardiac failure. We report two cases in which use of a proprietary combination diuretic containing a loop diuretic and potassium sparing agent with an angiotensin converting enzyme inhibitor was associated with hyperkalaemic cardiac arrest. Successful resuscitation from the arrest permitted elucidation of its mechanism. We believe that this outcome has not previously been reported, and emphasise the importance of electrolyte monitoring in patients receiving angiotensin converting enzyme inhibitors particularly if prescribed in addition to fixed combination proprietary diuretics.

A double-blind comparison of perindopril and hydrochlorothiazide-amiloride in mild to moderate essential hypertension

The aim of this 3-month double-blind multicenter trial was to compare the antihypertensive efficacy and tolerability of the ACE inhibitor perindopril with those of a diuretic combination. After 1 month of receiving placebo, 165 patients with essential hypertension were randomised to perindopril 4 mg (n = 82) or to 50 mg hydrochlorothiazide + 5 mg amiloride (n = 83). The patients were treated for 3 months with monthly assessments, "uncontrolled" patients (DBP greater than 90 mm Hg) had their dosage doubled and then, if necessary, atenolol 50 mg was added. At the end of the 3-month study, mean decreases in supine and standing systolic and diastolic blood pressures were similar in both groups. In the perindopril group, BP control was obtained in 56% of the patients with the 4 mg dosage and required an increase to 8 mg alone in 16% and with atenolol in 5%. The corresponding percentages in the diuretic group were 48, 23 and 13%. The overall percentage of "controlled" patients was similar in the 2 groups, respectively 78 and 84%. The nature and incidence of complaints were comparable in the 2 groups. Adverse laboratory changes were more frequent in the diuretic group: decrease in blood sodium (140.5 vs 139.1 mmol/l; P less than 0.01), potassium (4.2 vs 3.9 mmol/l; P less than 0.01) with 10 patients having significant hypokalemia, increase in blood urea, triglycerides and uric acid. By contrast, a transient increase in blood potassium with a decrease in triglycerides was observed in the perindopril group.

[Pulmonary edema induced by hydrochlorothiazide/amiloride (Moduretic)]

A 44-year-old woman was seen on three separate occasions for acute pulmonary edema which had developed 30 minutes after ingestion of a single hydrochlorothiazide-amiloride (Moduretic) tablet. Eighteen cases of hydrochlorothiazide-induced pulmonary edema have been reported previously. Clinical findings and investigations in the present and previous cases indicate a noncardiogenic cause for the pulmonary edema. Increased pulmonary vascular permeability is probably involved. So far, attempts to demonstrate an immunological mechanism have failed and the pathophysiology remains uncertain. The reaction may be difficult to differentiate from left ventricular failure in patients with cardiac disease. Attention should be drawn to this severe but rare side effect of a frequently used diuretic.

Cardiac conduction defects associated with hyponatremia

Cardiac conduction defects have not been previously described in association with hyponatremia, although in patients with congestive heart failure the frequency of ventricular premature beats was found to correlate to the severity of hyponatremia. We describe three patients with second-degree or complete atrioventricular (AV) block which occurred during or shortly after an episode of severe hyponatremia. The first had thiazide-induced hyponatremia while on amiodarone. In the second, definite etiology for hyponatremia which was associated with longstanding polydipsia could not be established. The third had ischemic heart disease and intermittent conversion of his first-degree to second-degree AV block while hyponatremic after diuretics use. Although it is usually difficult to single out hyponatremia as the cause of conduction defects which usually occur in the presence of cardiac disease, potent medications or other electrolyte abnormalities, we suggest that hyponatremia may play a role in the pathogenesis of conduction defects in the diseased heart.

Acute hyponatraemia following total hip replacement

An elderly woman who had been taking a fixed-dose combination of a thiazide and potassium-sparing diuretic for eight days, became severely hyponatraemic following total hip replacement. Her hyponatraemia resolved with fluid restriction, intravenous normal saline, and withdrawal of the drug. Hyponatraemia is a well-described side-effect of diuretic therapy; however, we are not aware of any previous reports of this condition developing acutely in the postoperative state. We attribute this to the natriuretic nature of the drug, compounded by the postoperative, anti-diuretic surge which itself may have been exacerbated by the drug. We thus advise caution in the use of this preparation in the elderly patient about to undergo major surgery.

Bumetanide/amiloride ('Burinex A'): a new combined preparation for the control of patients with congestive cardiac failure

Two hundred and thirty-three patients (66 males and 167 females), aged 24 to 92 years, with congestive cardiac failure were entered into a long-term study to evaluate the efficacy and tolerability of treatment with a fixed dose combination tablet containing 1 mg bumetanide and 5 mg amiloride. One hundred and fifty-five patients were treated for 52 weeks. The daily dosages were 1 tablet (113 patients), 2 tablets (35 patients), 3 or 4 tablets (7 patients). Treatment was associated with a marked reduction in the prevalence of ankle oedema, dyspnoea and pulmonary crepitations, and with statistically significant decreases in body weight, pulse rate and calf measurement. Mean serum potassium showed a small but statistically significant increase, but serious hyperkalaemia was not encountered. Although serum sodium decreased, serious hyponatraemia did not occur. No clinically significant effects on hepatic, renal or haemopoietic function were observed. Minor adverse effects, most of which resolved spontaneously, were reported by 60 patients. Only 14 (6.0%) patients ceased treatment because of adverse effects.

Antihypertensive efficacy and influence on physical activity of three different treatments in elderly hypertensive patients

The antihypertensive efficacy and subjective and physical tolerability of three different pharmacological treatments (metoprolol, captopril and the combination of hydrochlorothiazide + amiloride) were compared with placebo in 36 elderly hypertensives (aged 61-79 years), according to a Latin-square double-blind design. The placebo and the active treatments were administered for 2 months. Seated blood pressure was significantly reduced by all the pharmacological treatments compared with placebo, but only metoprolol significantly reduced the heart rate. No haematological or biochemical changes were observed during the study. Physical fitness, evaluated as endurance in a standard cycle ergometer exercise test, was slightly decreased after the treatment with metoprolol and the diuretic combination and slightly improved after treatment with captopril. Subjective tolerability, evaluated by a check-list of symptoms, was better during the active therapies, and in particular during the captopril treatment, than during the placebo treatment. Our results indicate that all three active treatment regimens significantly reduce blood pressure in elderly hypertensives and that captopril appears slightly better tolerated physically and subjectively.

Ibopamine versus hydrochlorothiazide/amiloride in patients with mild congestive heart failure. SK & F Ibopamine Working Group

The clinical efficacy and safety of ibopamine and diuretic therapy were compared in a multicenter, multinational, parallel, positive-controlled, randomized, double-blind, 12-week study, involving 103 patients with mild CHF (NYHA Class II). Body weight, NYHA functional class, symptom assessment scores, laboratory blood tests, and exercise testing were evaluated at baseline at interim visits and at the end of 12 weeks. Clinical events were monitored throughout the study. There was no difference in any of the considered parameters between the two patient groups at baseline and at the end of the 12-week evaluation. A trend of improvement in clinical conditions that did not reach statistical significance was noted in each group throughout the study, as a probably "trial effect." Five patients on ibopamine had severe clinical events leading to drug discontinuation (CHF worsening, ventricular tachycardia, elevation of liver transaminases, headache, gastrointestinal disorders) and five on diuretic therapy experienced serious side effects (skin rash, palpitation, atrial fibrillation, elevation of liver transaminases, manic episode). One patient died while on diuretic therapy. Only headache and skin rash were considered to be related to the therapy (ibopamine and diuretic therapy, respectively). Our trial suggests that ibopamine can be safely and effectively used as an alternative for diuretics for up to 3 months in patients with mild CHF.

Comparison of indapamide and hydrochlorothiazide plus amiloride as a third drug in the treatment of arterial hypertension

In a randomized, double-blind crossover trial, indapamide (IND) 2.5 mg and hydrochlorothiazide 25 mg + amiloride 2.5 mg (HCTZ + A) were found to be equally effective in reducing blood pressure (BP) in 13 patients with moderate to severe hypertension already receiving chronic treatment with a beta blocker and a vasodilatator (supine BP during run-in: 169/103 +/- 21/5 mmHg; on IND: 149/91 +/- 21/14 mmHg; on HCTZ + A 144/88 +/- 23/5 mmHg). Both drugs induced insignificant reductions in body weight, and no change in plasma volume was seen. Serum potassium was significantly reduced on both regimens--the values recorded on IND being significantly lower than those seen on HCTZ + A. Values below 3.0 mmol/l were found in two patients receiving IND, but no subjective side effects were reported. Hyperuricemia occurred with the same frequency on both regimens. It is concluded that IND, just like the thiazide diuretics, is useful as the third drug in patients needing triple drug therapy to control BP, but metabolic adverse effects are not avoided by the choice of this drug.