Cocaine

Cocaine is an alkaloid derived from the coca plant. It is widely used as a recreational stimulant. The price of cocaine has fallen sharply in the past decade resulting in cocaine toxicity becoming a much more frequent clinical problem. This increase has made cocaine a favourite topic of question writers.

Mechanism of action

• cocaine blocks the uptake of dopamine, noradrenaline and serotonin

Adverse effects

• cardiovascular
  • coronary artery spasm → myocardial ischaemia/infarction
  • both tachycardia and bradycardia may occur
  • hypertension
  • QRS widening and QT prolongation
  • aortic dissection
• neurological
  • seizures
  • mydriasis
  • hypertonia
  • hyperreflexia
• psychiatric effects
  • agitation
  • psychosis
  • hallucinations
• others
  • ischaemic colitis is recognised in patients following cocaine ingestion. This should be considered if patients complain of abdominal pain or rectal bleeding
  • hyperthermia
  • metabolic acidosis
  • rhabdomyolysis

Management of cocaine toxicity

• in general, benzodiazepines are generally first-line for most cocaine-related problems
• chest pain:
  • benzodiazepines + glyceryl trinitrate
  • if myocardial infarction develops then primary percutaneous coronary intervention
• hypertension: benzodiazepines + sodium nitroprusside
• the use of beta-blockers in cocaine-induced cardiovascular problems is a controversial issue
  • the American Heart Association issued a statement in 2008 warning against the use of beta-blockers (due to the risk of unopposed alpha-mediated coronary vasospasm) but many cardiologists since have questioned whether this is valid
  • if a reasonable alternative is given in an exam it is probably wise to choose it