Effects of tiodazosin, a new antihypertensive, hemodynamics and clinical variables

Tiodazosin, a new antihypertensive, resembles prazosin in structure and α-adrenergic-blocking activity, and it also exerts a direct vasodilator effect. We evaluated its long-term hemodynamic and systemic effects in patients with essential hypertension. Our data show that after 10 wk of therapy with tiodazosin, 7 of our 10 patients had significant reduction in intra-arterial mean blood pressure as a result of a fall in systemic vascular resistance. Heart rate, cardiac output, and plasma volume did not change. Systemic effects were minor and included a gain in weight and a reduction in hemoglobin, hematocrit, platelet count, serum protein, albumin, bilirubin, and specific gravity of urine. No patient initially developed orthostatic symptoms after the first dose, but there were transient episodes of light-headedness in three patients, palpitations in two, increased urinary frequency in one, and drooping of eyelid in another during the trial period. One patient developed profound orthostatic hypotension, which could be attributed to the drug. Because of such side effects and the failure to lower blood pressure in 30% of patients with essential hypertension, tiodazosin appears to have several important drawbacks and little advantage over currently available antihypertensives. Clinical Pharmacology and Therapeutics (1983) 34, 290–296; doi:10.1038/clpt.1983.170