Clinical trial of mefruside, a new diuretic

Comparison of withdrawing antihypertensive therapy between diuretics and angiotensin converting enzyme inhibitors in essential hypertensives

One hundred thirteen patients with essential hypertension receiving single or multiple antihypertensive agents were enrolled in the study. All had had mild to severe hypertension before treatment, but their diastolic blood pressure (DBP) at study entry was lower than 90 mm Hg for all measurements. In half of the subjects, non-thiazide diuretics (n = 35) or angiotensin-converting enzyme inhibitors (ACEI, n = 37) were discontinued, and their remaining drugs were maintained throughout the study. The other patients (n = 41) continued all their medications. Forty-one percent of subjects remained normotensive for 12 months after withdrawal of diuretics, and 37% of patients with ACEI discontinuation remained normotensive, although the recurrence of hypertension after withdrawal of ACEI tended to be earlier than its recurrence after withdrawal of diuretics. Serum uric acid and creatinine concentration decreased after diuretic withdrawal, but not after ACEI withdrawal. Diuretic withdrawal resulted in an increase in serum potassium, but ACEI withdrawal induced a decrease in serum potassium. Withdrawal of diuretics or ACEI both significantly reduced plasma renin activity. The present study may be indicative of the ability to withdraw some medications in many patients being treated with multiple antihypertensive agents.

Haemodynamic effects of four months' mefruside therapy in hypertensive patients

The haemodynamic changes after 4 months' mefruside therapy in 13 patients with essential hypertension have been studied. Intraarterial BP was significantly reduced both at rest supine and during standardized leg exercise in sitting position. The reduction was caused mainly by a decrease in cardiac output in about half of the patients and mainly by a decrease in total peripheral vascular resistance in the remainder. Thus, for the total material there was no significant change in either cardiac output or total peripheral vascular resistance. At rest, however, there was a significant decrease in storke volume (p less than 0.05) and an increase in heart rate (p less than 0.05). On changing from supine to sitting position, the average systolic and diastolic pressures increased before and decreased after therapy, the differences being significant. The results indicate that the hypotensive effect of long-term saluretic therapy is accomplished by a decrease in cardiac output and/or peripheral vascular resistance, with large interindividual variations.

Effect of equivalent antihypertensive doses of mefruside and cyclopenthiazide on serum electrolytes, uric acid and glucose tolerance in hypertensive patients

1. A comparative cross-over trial of mefruside and cyclopenthiazide, each drug being given for 6 weeks, was conducted on thirty hypertensive patients with diabetes mellitus or impaired glucose tolerance. Other antihypertensive therapy, any antidiabetic therapy and potassium supplementation were kept constant throughout the trial. Dosages of mefruside and cyclopenthiazide were adjusted to give approximately equal blood pressure levels in the two drug periods. 2. There was no significant difference in the following parameters studied during the sixth week of each of the two periods of drug therapy: serum electrolytes, total CO2, chloride, urea, amylase, haemoglobin, erythrocyte sedimentation rate, platelet and white blood cell counts, lying and standing blood pressure and pulse rate, weight, fasting and 2-h glucose and insulin levels and five-value glucose and insulin curve areas, fasting calcium and phosphate. 3. Serum creatinine and uric acid showed a small but significant fall during mefruside therapy.

Xipamid, a potent new diuretic

The effects of xipamid and frusemide were comapred in 9 oedematous patients. Xipamid was found to be equipotent with frusemide in doses of 40 mg. and 80 mg., with respect to its effect on sodium and water excretion. The time course of action of xipamid was observed to be more prolonged than that of frusemide. It is concluded that xipamid is a potent and safe diuretic.

Diuretics: mechanism of action and clinical application

Despite the bewildering number of diuretics available to the physician, these drugs can be divided into 4 main groups, characterised by their site of action on sodium reabsorption in the kidney. Drugs acting on the ascending limb of the loop of Henle have a powerful but short acting diuretic effect; they include frusemide, ethacrynic acid and bumetanide. The benzothiadiazines and related compounds have a moderate diuretic action spread over a longer period, whilst the potassium-sparing diuretics, triamterene, amiloride and spironolactone, have only a weak diuretic effect but a marked ability to diminish urinary potassium excretion. The fourth group is made up of miscellaneous substances which function as vasodilator or osmotic agents. The pathogenesis of oedema formation in heart failure is outlined and a logical approach to treatment suggested. Duiretics are being increasingly used in the treatment of non-oedematous states, in particular hypertension, diabetes insipidus and hypercalciuria; their exact role in pregnancy and acute renal failure remains controversial. Side-effects can be related to their effect on electrolyte excretion and include hypokalaemia, hyponatraemia, hyperkalaemia and hyperuricaemia. The incidence of disturbed carbohydrate tolerance in previously normal individuals is low. Other less common side-effects are also discussed.