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 CCPU (RCE, Biliary, DVT, E-FAST, AAA) Rob is an Emergency Medicine Advanced Trainee based in Melbourne, Australia. He has special interests in medical education, ECG interpretation, and the use of diagnostic and procedural ultrasound in the undifferentiated and unwell patient.

Follow him on twitter: @rob_buttner | ECG Library |

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