Pharm 101: Colchicine

Class

Antiinflammatory agent

Pharmacodynamics

• Anti-inflammatory effect:
  • Binds to intracellular protein tubulin
  • Results in depolymerisation of microtubules and reduced cell motility
  • Prevents migration of neutrophils into joint
• Also inhibits formation of leukotriene B4 and IL-1B
• No effect on uric acid metabolism

Pharmacokinetics

• PO administration, well absorbed
• Peak plasma level 2 hours
• Half-life 9 hours
• Metabolites excreted in GIT and urine

Clinical uses

• Acute treatment of gout
  • Relieves and pain and inflammation of gouty arthritis in 12-24 hours without altering metabolism or excretion of urates
  • Single 1.2mg dose followed by 0.6mg dose
• Prophylaxis of gout
  • Most common use
  • In between attacks
  • 0.6mg 1-3x per day
• Pericarditis

Adverse effects

• GIT upset:
  • Diarrhoea
  • Nausea/vomiting/abdominal pain less commonly
• Uncommon (previously with IV administration):
  • Hepatic necrosis
  • Acute renal failure
  • DIC
  • Seizures
• Rare:
  • Hair loss
  • Bone marrow depression

Further reading

• Robinson P, Stamp L. The management of gout: Much has changed. RACGP, Australian Family Physician. Vol 45:5. 2016: 299-302

References

• Katzung BG. Basic and Clinical Pharmacology. 14e. 2018: 660-661