Alpha-1 receptor blocker

  • Selective alpha-1 receptor blocker in arterioles and venules
    • Affinity 1000-fold greater than that for alpha-2 receptors
  • Reduces BP by dilating both resistance and capacitance vessels
  • Alpha-1 selectivity allows noradrenaline to exert unopposed negative feedback (mediated by presynaptic alpha-2 receptors) on its own release
  • 50% first pass metabolism
  • Extensive metabolism
  • Half-life 3 hours
Clinical uses
  • Chronic hypertension
  • Benign prostatic hyperplasia
  • Raynaud’s phenomenon (uncommon)
Adverse effects
  • Postural hypotension
  • Headache, lassitude
  • Reduced prostate smooth muscle tone, thus alleviating prostatic urinary obstruction
  • Positive serum antinuclear factor
  • Increased HDL concentration

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

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