prazosin

Last reviewed 01/2018

This is an alpha-adrenoceptor blocker.

The first dose of prazosin may provoke hypotensive collapse so it should be given in the evening with the patient in bed. Blood pressure should be monitored.

The indications for prazosin are:

  • cardiovascular disease:

    • hypertension:
      • 500 mcg 2-3x/day
      • increase dose to 1 g 2-3x/day after a week
      • maximum daily dose is 20 mg

    • congestive cardiac failure:
      • 500 mcg 2-4x/day
      • increase dose to 1 g 4x/day after a week
      • maximum daily dose is 20 mg

    • Raynaud's syndrome:
      • 500 mcg 2x/day
      • increase dose to 1-2 g 2x/day after a week

  • symptomatic benign prostatic hyperplasia:
    • causes relaxation of smooth muscle in the bladder neck
    • 500 mcg 2x/day
    • after a week increase dose according to response
    • usual maintenance dose is 2 mg 2x/day