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.