CHANGES IN URINARY ENZYME LEVELS FOLLOWING THE USE OF ANTIHYPERTENSIVE AGENTS IN PATIENTS WITH ESSENTIAL-HYPERTENSION

When choosing antihypertensive agents for the treatment of hypertensio n, it is necessary to consider the predisposition of individuals to re nal damage, which may be associated with the long-term effect of such agents. In this respect, this study examined the effect of two commonl y used antihypertensive drugs (Brinerdin and Minizide) on renal functi on over 24 months in patients diagnosed as having essential hypertensi on. We utilized urinary enzyme studies, which are indicators of subtle renal dysfunction. Other parameters of glomerular and tubular functio n were also determined in the pretreatment period, as well as during a nd at the end of treatment of 28 patients (16 males and 12 females) wi th therapeutic doses of Brinerdin and 22 patients (12 males and 10 fem ales) with conventional doses of Minizide. During the follow-up period , blood pressure (BP) fell from a mean of 160/108 +/- 9/4 (SD) mmHg to 130/90 +/- 7/4 on Brinerdin and from a mean of 160/106 +/- 5/2 (SD) m mHg to 130/90 +/- 8/5 on Minizide. There was no significant difference in the levels of BP between the patients taking Minizide and those ta king Brinerdin before, during, and at the end of treatment. Significan t elevation (p < 0.05) of the levels of urinary protein, lactate dehyd rogenase (LDH), and N-acetyl-B-D-glycosaminidase (NAG) was observed in patients on Minizide during treatment, and these levels remained elev ated during the latter part of the study. Normotensive, untreated, age - and sex-matched control subjects showed no such urinary parameter ch anges. While NAG activity was significantly elevated in the Brinerdin- treated patients, other parameters remained within comparable levels t o those of normotensive, untreated control subjects throughout the per iod of study. However, a significant reduction in the serum potassium level (-0.58 +/- 0.06 mmol/l) was observed following Minizide therapy compared with a mild reduction (-0.25 +/- 0.05 mmol/1) following Brine rdin treatment. Female and male patients exhibited similar patterns of response to the two drugs. The results of the present study suggest t hat transient but subtle tubular injury has been induced by the use of the two drugs with a more profound effect from the use of Minizide.