Research Article

Influence of dosage and dietary sodium on the first-dose effects of prazosin.

Br Med J 1977; 1 doi: (Published 11 June 1977) Cite this as: Br Med J 1977;1:1507
  1. G S Stokes,
  2. R M Graham,
  3. J M Gain,
  4. P R Davis


    The effects of the first dose of prazosin were assessed in hypertensive patients on different sodium intakes. Patients received 250, 100, or 30 mmol sodium per 24 hours for a week before taking 2 mg or 0-5 mg prazosin. The acute effects of prazosin on blood pressure and pulse rate were milder with a high sodium intake. On the 100-mmol intake symptomatic postural hypotension occurred in five out of seven patients given 2 mg prazosin and in two out of four given a 0-5-mg dose, whereas those taking 2 mg or 0-5 mg and a 250-mmol sodium intake experienced no postural symptoms. These findings indicate that particular care should be taken in starting prazosin treatment in sodium-depleted patients.