An evaluation of the efficacy and safety of doxazosin in the treatment of hypertension associated with renal insufficiency.

The efficacy, safety and potential effect on renal function of doxazosin were studied in hypertensive patients with renal impairment. Thirty adult patients with moderate hypertension (DBP between 95-114 mmHg and SBP less than 210 mmHg) and moderately impaired renal function of varying underlying pathology (serum creatinine between 220-640 mumol/l) were given doxazosin, either as monotherapy or part of polytherapy, in an open study. Their average duration of doxazosin therapy was 75 days and the median dose was 2 mg. With doxazosin treatment, the mean supine and standing SBPs were reduced by 15 mmHg and 13 mmHg, respectively. These changes were highly significant (P less than 0.0001). Supine and standing DBPs were also significantly reduced by 16 mmHg and 17 mmHg, respectively (P less than 0.0001). Heart rate was increased by 4 beats/min (mean maximum change); this was statistically, but not clinically, significant. There was a small but significant rise in serum creatinine (mean value, 35 mumol/l) in the group as a whole over a mean period of 75 days. This was considered to be compatible with the natural progression of the underlying renal pathology. Retrospective plotting of the reciprocal of available serum creatinine values against time during the months before doxazosin therapy yielded a linear relationship which supported this hypothesis. One patient withdrew from the study because of a rapid rise in serum creatinine concentration during the placebo run-in phase. Overall, side effects were minimal and did not necessitate reducing the dosage or discontinuing active therapy. The results of this study indicate that doxazosin is effective and well-tolerated in the treatment of hypertension with concomitant renal insufficiency and does not appear to compromise renal function.