One year follow-up of hyperuricaemic hypertensive patients treated with tienilic acid or a diuretic with or without uric acid-lowering drugs

Tienilic acid in patients with impaired renal function

Diuretic therapy is usually accompanied by biochemical changes, such as hypokalemia, impaired glucose tolerance and hyperuricaemia. Tienilic acid is a new long-acting diuretic with antihypertensive effect, combined with uricosuric property. For the purpose of evaluating the effect of tienilic acid in patients with impaired renal function, eleven patients with hypertension and slight to moderate renal impairment were randomized to either hydrochlorothiazide or tienilic acid therapy. During eight weeks of treatment no changes occurred in serum-creatinine, creatinine-clearance, serum-sodium, or urea. Despite renal impairment, serum uric acid decreased during tienilic acid treatment. Compared with placebo, a significant decrease in uric acid was seen as early as after one week of treatment (p less than 0.01) and after 8 weeks the difference was still of the same order (p less than 0.01). During hydrochlorothiazide therapy, serum uric acid increased progressively. The difference was p less than 0.002 at 4 weeks and p less than 0.0005 at 8 weeks of treatment, compared with placebo. The results of this study show that the uricosuric effect of tienilic acid is maintained in patients with mild to moderate renal impairment.

Interaction of allopurinol and hydrochlorothiazide during prolonged oral administration of both drugs in normal subjects. I. Uric acid kinetics

The interaction of allopurinol (300 mg/day) and hydrochlorothiazide (50 mg/day) was studied in seven healthy male volunteers during prolonged coadministration of the two drugs using defined dietary conditions. A formula diet was administered with the allopurinol throughout the 24-day study, while hydrochlorothiazide was added during days 11-21. After the addition of hydrochlorothiazide both plasma uric acid and plasma oxipurinol rose for 6 days--24% and 30%, respectively, compared to steady-state levels during allopurinol alone (P < 0.01 each). In neither substance were variations in renal excretion significant. By the end of combined treatment (day 21), the changes induced by hydrochlorothiazide had already been reversed to a considerable extent. It is concluded that both in normal individuals and in patients with normal renal clearance of uric acid the effect of hydrochlorothiazide on the plasma concentration and renal excretion of oxipurinol is small. When taking both drugs, there is no increased risk during long-term treatment, and a risk is even questionable during the first days.

Angiotensin I converting enzyme inhibitors and the renal excretion of urate

Hyperuricaemia carries with it a high risk of tophi development affecting connective tissue in kidney, skin and joints, its overt clinical expression being gout. Diuretics, which are invariably prescribed in congestive heart failure and widely used for the treatment of essential hypertension, may cause hyperuricaemia and predispose to gout by inducing renal retention of urate. The angiotensin I converting enzyme inhibitors captopril and enalapril have been found to augment renal urate excretion both in normal volunteers and in hypertensive patients. Current evidence appears to indicate that the uricosuric effect of captopril and enalapril could be due to the rises in renin and angiotensin I these drugs elicit by angiotensin I converting enzyme inhibition, and/or to pharmacological actions not related, at least directly, to the renin-angiotensin-aldosterone system. Serum urate levels have been significantly reduced by monotherapy with captopril in hypertensive patients suffering from hyperuricaemia. Diuretic-induced hyperuricaemia in hypertensive patients can be prevented or counteracted by the administration of captopril and enalapril. Available clinical data support the argument that captopril and enalapril should be used as first choice drugs for the treatment of hyperuricaemic hypertensive patients. When diuretic-induced hyperuricaemia develops in patients suffering from congestive heart failure, captopril or enalapril should be added to the therapeutic regime in doses capable of countering the shift in plasma urate concentration, provided the clinical condition of the patients permits such additional pharmacological treatment. Therapy with captopril and enalapril should preferably be instituted in a gradual manner, especially in patients with hyperuricaemia, in order to prevent the precipitation of urate in the kidney and in the urinary tract.

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.