Contrasting effects of vasodilators on blood pressure and sodium balance in the hypertension of autonomic failure

Supine hypertension, which is very common in patients with autonomic failur e, limits the use of presser agents and induces nighttime natriuresis. In 1 3 patients with severe orthostatic hypotension due to autonomic failure (7 women, 6 men, 72 +/- 3 yr) and supine hypertension, the effect of 30 mg nif edipine (n = 10) and 0.025 to 0.2 mg/h nitroglycerin patch (n = 11) on supi ne BP, renal sodium handling, and orthostatic tolerance was determined. Med ications were given at 8 p.m.; patients stood up at 8 a.m. Nitroglycerin wa s removed at 6 a.m. Compared with placebo, nifedipine and nitroglycerin dec reased systolic BP during the night by a maximum of 37 +/- 9 and 36 +/- 10 mmHg, respectively (P < 0.01). At 8 a.m., supine systolic BP was 23 +/- 7 m mHg lower with nifedipine than with placebo (P < 0.05), but was similar wit h nitroglycerin and placebo. Sodium excretion during the night was not redu ced with nitroglycerin (0.13 +/- 0.02 mmol/mg creatinine [Cr] versus 0.15 /- 0.03 mmol/mg Cr with placebo), but it was increased with nifedipine (0.3 5 +/- 0.06 mmol/mg Cr versus 0.13 +/- 0.02 mmol/mg Cr with placebo, P < 0.0 5). Nifedipine but not nitroglycerin worsened orthostatic hypotension in th e morning. It is concluded that nifedipine and transdermal nitroglycerin ar e effective in controlling supine hypertension in patients with autonomic f ailure. However, nifedipine has a prolonged depressor effect and worsens or thostatic hypotension in the morning. The decrease in pressure natriuresis that would be expected with the substantial decrease in BP obtained with ni troglycerin and nifedipine may be offset by a direct effect of both drugs o n renal sodium handling.