Use of Prazosin at the Dunedin Hypertension Clinic: Controlled and Open Studies and Pharmacokinetic Observations

Prazosin has been used as an antihypertensive drug in the treatment of 93 patients in Dunedin since 1971-1972, mainly those whose previous control was unsatisfactory. It has led to very significant improvement of control in many cases; 48 patients now receiving the drug have taken it for an average of 30 months. Forty-five patients have stopped taking the drug for various reasons, such as failure to respond (11-8%), side effects (20-4%), myocardial infarction (8-6%) or unrelated reasons (7-5%). This reflects to some extent the use ofa new drug in patients who are difficult to control, and its use initially without concomitant diuretic and beta-blocker therapy. We believe that the place of praxosin is primarily as a third drug for patients whose hypertension does not respond satisfactorirly to a diuretic and a beta-blocker. The first dose must be kept small, preferably 0-25 mg, and even with this dose a small proportion of patients receiving diuretic and beta-blocker therapy seem to become hypotensive; patients should be warned about this. The plasma half-life in normal volunteers was 3-8 hours but in some patients it seems to be considerably longer.