Antihypertensive and hemodynamic effects of ticrynafen compared with hydrochlorothiazide

Plasma atrial natriuretic peptide and the renin-aldosterone system during long-term administration of the diuretic xipamide in man

We have studied the effect of xipamide on plasma alpha-atrial natriuretic peptide and the renin-aldosterone-kallikrein system in twelve healthy men, using a double-blind cross-over design. After a run-in period on placebo for 1 week the subjects were treated with either placebo (n = 6) or xipamide 20 mg once daily (n = 6) for 16 weeks and were then switched to the alternative medication for another 16 weeks. The plasma concentration of alpha-atrial natriuretic peptide fell after 1 week of xipamide administration and increased during prolonged xipamide administration but remained suppressed. The changes in plasma alpha-ANP observed after 1 week of xipamide were negatively correlated with the changes in haematocrit and haemoglobin. Plasma renin activity (PRA), aldosterone concentration (PAC), and urinary excretion of aldosterone and kallikrein increased after 1 week of xipamide administration, levelled off during the second and fourth weeks, but remained elevated during further prolonged xipamide administration for 16 weeks. The xipamide-induced changes in PRA and PAC were positively correlated with the changes in the haematocrit and haemoglobin. Our data suggest that the changes in plasma renin, aldosterone, and alpha-atrial natriuretic peptide during xipamide administration may be related to diuretic-induced volume contraction.

Comparison of propranolol or hydrochlorothiazide alone for treatment of hypertension. III. Evaluation of the renin-angiotensin system

In this study, the relation between renin activity and therapeutic response to hydrochlorothiazide or propranolol was studied. Patients with a diastolic blood pressure of 95 to 114 mm Hg were treated with propranolol (40 to 320 mg twice daily) or hydrochlorothiazide (25 to 100 mg twice daily). The initial renin profiles were: low, 56 percent (n = 300); normal, 33 percent (n = 174); high, 11 percent (n = 60). A greater incidence of low and fewer high renin profiles (p less than 0.001) were observed in blacks. After furosemide administration (40 mg intravenously), 55 percent of patients (n = 291) had a low renin response and 45 percent (n = 240) had a normal renin response. No correlation between renin profile and renin response was observed, although low renin response and low renin profile occurred more frequently in older patients. Hydrochlorothiazide administration resulted in a greater decrement in diastolic blood pressure (p less than 0.05) in the total group. Irrespective of renin activity, both hydrochlorothiazide and propranolol reduced diastolic blood pressure. When renin profile was considered, no significant variation in response to hydrochlorothiazide therapy was observed, and there was a greater reduction in diastolic blood pressure in the patients with a high renin profile receiving propranolol. In comparing therapeutic response, patients with a low renin profile had a better response to hydrochlorothiazide, and propranolol was more effective in patients with a high renin profile. The anticipated effect of therapy on plasma renin activity was observed. Although these results are consistent with a volume-vasoconstrictor analysis of hypertension, the results of therapy could not have been prejudged from renin profile or responsivity. The slight differences observed do not warrant the expense of renin determinations when a simple determination of therapeutic response is sufficient.

Multicentre controlled trial of tienilic acid in hyperuricaemic, hypertensive subjects, with intensive monitoring of liver function

1 Tienilic acid, a diuretic with potent uricosuric properties, has been compared with conventional diuretic therapy, mainly thiazide, in a parallel group (random allocation) multicentre study in hyperuricaemic hypertensives (n = 96). 2 The study was designed to last 1 year but tienilic acid was withdrawn for suspected hepatotoxicity before the study was complete. Mean follow-up was 8.5 (range 1-12) months and the mean daily dose of tienilic acid was 278 (range 125-500 mg). 3 Blood pressure levels on tienilic acid and on conventional diuretics were similar. 4 Serum potassium and sodium levels were also similar in the two groups, but serum urea and creatinine rose somewhat more in the tienilic acid group. 5 Serum uric acid fell dramatically in the patients on tienilic acid from 0.56 to 0.32 mmol/l, but did not alter significantly in the control group. 6 There were no problems with renal failure or urate deposition probably because patients were instructed to drink plenty of fluid when tienilic acid was started, because initial dose was low and because all previous diuretics were stopped for 3 days before tienilic acid was started. 7 Mean liver function indices did not rise in either group. Mild elevation in liver enzymes occurred in one control patient and one patient on tienilic acid; the latter drug was stopped and the values returned to normal. 8 The general incidence of side-effects was low. 9 Our impression was that tienilic acid was a useful drug. Whether it could have been used safely with monitoring of liver function will not now be known.

Effect of chronic diuretic treatment on the plasma renin-angiotensin-aldosterone system in essential hypertension

1 Chronic treatment with a constant dose of hydrochlorothiazide or tienilic acid increases plasma renin activity (PRA) acutely to reach a maximum within the first week. 2 During chronic diuretic therapy from 1 month to 1 year, PRA remained elevated at a rather constant level, though this was somewhat lower than the maximum level reached after 1 week. 3 A significant (P less than 0.01) correlation (r = 0.74) between changes in plasma angiotensin II and renin activity provoked by chronic treatment for 3 months with hydrochlorothiazide and tienilic acid was found. 4 The increase in plasma aldosterone during chronic treatment with hydrochlorothiazide and tienilic acid (1000 mg) is related (r = 0.68; P less than 0.01) to the rise in plasma angiotensin II.

Effect of tienilic acid and amiloride in healthy volunteers and in hypertensives with normal renal function

1 A double-blind comparison of the effect of tienilic acid (250 mg) and amiloride (5 mg) on renal function in healthy volunteers and of tienilic acid plus amiloride compared to hydrochlorothiazide (50 mg) plus amiloride in patients with mild to moderate essential hypertension for safety and hypotensive efficacy was made.

2 Renal plasma flow ([I¹²⁵] iodohippurate clearance) and glomerular filtration rate ([I¹³¹] iothalamate clearance and 24 h creatinine clearance) were not affected by tienilic acid or amiloride alone or in combination despite a rise in plasma urea and plasma creatinine (within the normal range) in healthy volunteers.

3 In hypertensive patients tienilic acid and tienilic acid plus amiloride treatments caused a rise in plasma urea and plasma creatinine similar to hydrochlorothiazide and hydrochlorothiazide plus amiloride but no significant change in creatinine clearance occurred with any of the treatments.

4 Tienilic acid and hydrochlorothiazide caused hypokalaemia in the patients which was normalized by addition of amiloride. Fewer subjects became hypokalaemic when amiloride was added to tienilic acid than when tienilic acid was given alone.

5 The antihypertensive effect of tienilic acid and tienilic acid plus amiloride was similar to hydrochlorothiazide and hydrochlorothiazide plus amiloride in patients with hypertension. No effect on blood pressure was observed in the healthy volunteers.

6 Plasma uric acid was significantly reduced by tienilic acid alone and in combination in patients and subjects whereas a significant elevation occurred with hydrochlorothiazide.

7 Side effects were increased when amiloride was added to either tienilic acid or hydrochlorothiazide, but side effects were less common after treatment with tienilic acid than following hydrochlorothiazide.

8 The combination of tienilic acid plus amiloride significantly reduces blood pressure and appears to be well tolerated with no adverse effects on renal function or plasma potassium in patients with mild to moderate hypertension and normal renal function. Addition of amiloride may be useful if hypokalaemia occurs following tienilic acid therapy in such patients.