Medicine & USMLE

Alpha-1 Blockers

Cardio Drugs - Blood Pressure
  1. ACE Inhibitors
  2. Angiotensin II Receptor Blockers (ARBs)
  3. Beta Blockers: Mechanisms and Clinical Uses
  4. Beta Blockers: Side Effects
  5. DHP Calcium Channel Blockers
  6. Hydralazine
  7. Aliskiren
  8. Nitroprusside
  9. Alpha-1 Blockers
  10. Clonidine


Alpha-1 blockers are recognizable by their “-osin” ending, including the drug name tamsulosin.

They work by causing smooth muscle relaxation, leading to vasodilation.

Alpha-1 blockers can be used to treat BPH. They also can treat hypertension, with the exception of tamsulosin.

A common side effect is orthostatic hypotension, especially after the first dose. Other side effects include edema, nasal congestion, and reflex tachycardia.

They should be taken at night to minimize the risk of falls associated with orthostatic hypotension.

Key Points

  • Alpha-1 Blockers
    • Drug Names
      • -osin Ending
        • Tamsulosin
        • Prazosin
        • Doxazosin
        • Terazosin
    • Mechanism
      • Smooth muscle relaxation
        • Relaxation of the arteries - vasodilation
        • Relaxation of the smooth muscle in the bladder, ureters and prostate
    • Clinical Use
      • Hypertension
        • Except tamsulosin
        • Vasodilation causes pressure inside the arterial walls to decrease
      • Benign Prostate Hyperplasia (BPH)
        • Relaxation of the smooth muscle in the urinary tract allows for easier urine flow
        • Helps relieve urine retention in patients with BPH
    • Side Effects
      • Cause first dose orthostatic hypotension
        • A sudden drop in blood pressure caused by sudden changes in movement. Often leads to dizziness and/or lightheadedness.
        • Most likely to occur with the initial dose
      • Cause nasal congestion
        • Vasodilation of blood vessels in the nose leads to swelling of the nasal mucosa
      • Cause reflex tachycardia
        • As the blood pressure drops, the body responds by increasing the heart rate
      • Cause edema
    • Administration
      • Take at night/bedtime
        • Reduces risk of falls due to orthostatic hypotension