Class

Alpha-1 receptor blocker


Pharmacodynamics
  • 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

Pharmacokinetics
  • 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

References

Pharm 101 700

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) 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

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.