Effects of xanthine oxidase inhibition with allopurinol on arterial blood pressure depending on antihypertensive therapy

Background Arterial hypertension is commonly associated with hyperuricemia. Numerous clinical studies have shown that xanthine oxidase inhibition reduces arterial blood pressure in animal models. Furthermore, allopurinol appears to reduce blood pressure in adolescents with newly diagnosed hypertension. The results of studies represent a potentially new therapeutic approach, that of control of biochemical cause of hypertension, rather than non-specifically lowering blood pressure. Allopurinol appears to have effect an endothelial function in hypertensives in contrast to uricosuric agents. The aim of our study was to determine the effects of allopurinol on arterial blood pressure depending on hypouremic action of angiotensin converting enzyme inhibitor (ACE-I) or thiazide therapy. Material and Methods The research was carried out in years 2006-2008 in the Department of Hypertension, Angiology and Internal Diseases, University of Medical Sciences in Poznan. 66 patients with primary, mild-to-moderate arterial hypertension diagnosis based on traditional measurements were qualified for research. The patients with suspected or diagnosed secondary hypertension, white-coat hypertension, unstable coronary heart disease, myocardial infarction in history, diabetes and other coexisting chronic illness were excluded. Patients aged 25 to 70 (mean age 46.17 +/- 10.89) have been studied. Antihypertensive therapy was based on perindopril (n = 35) and hydrochlo-rothiazide (n = 31). After 8 weeks of antihypertensive therapy, allopurinol 150 mg daily was added for 2 months. Vitits were conducted in the morning. Following 1-h of rest, blood samples were collected for measurement of urate, urea, creatinine, glucose, renin acivity, liver function tests, electrolytes, plasma lipids, morphology. Ambulatory blood pressure monitoring (ABPM) was made. Twentyfour-hour urate excretion was evaluated. Measurements were taken at baseline, after 8 weeks of antihypertensive therapy and after next 8-week of antihypertensive therapy plus allopurinol. Results In the whole studied group SBP at visit V4 was 134,45 +/- 7,37 mm Hg, DBP 83,72 +/- 5,87 mm Hg, PP 50,78 +/- 7,31 mm Hg. In V5, the mean SBP, DBP and PP were: 134,89 +/- 7,93 mm Hg, 84,35 +/- 7,29 mm Hg and 50,54 +/- 7,53 mm Hg (no significant changes). In P+II group, at V4 the mean SBP24h was 128,87 +/- 9,1 mm Hg, DBP24h 78,20 +/- 6,82 mm Hg and PP24h 50,67 +/- 6,99 mm Hg. After allopurinol treatment in whole group, no significant changes in office SBP, DBP and ambulatory SBP, DBP were observed. Also, no significant changes in office BP and ambulatory BP were observed after treatment with allopurinol in group P and H. Conclusions 1. There were no significant changes in blood pressure after allopurinol treatment regardless of uric acid level reduction. 2. Arterial blood pressure after the antihypertensive therapy was correlated with the effectiveness of allopurinol. The lower was arterial blood pressure, the less effective was allopurinol.