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

The use of cocaine is associated with a wide variety of adverse effects:

Cardiovascular effects

• myocardial infarction
• both tachycardia and bradycardia may occur
• hypertension
• QRS widening and QT prolongation
• aortic dissection

Neurological effects

• 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 benzodiazipines are generally first-line for most cocaine related problems
• chest pain: benzodiazipines + glyceryl trinitrate. If myocardial infarction develops then primary percutaneous coronary intervention
• hypertension: benzodiazipines + 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