Cocaine overdose
Pharmacology
- Absorbed across all mucosal surfaces
- Hydrochloride form insufflated or injected IV
- Ether extraction produces crack cocaine, which is heat stable and can be smoked
- Nasal use = peak effect after 30 mins / duration of 1-3 hours - delayed and prolonged effect due to vasoconstriction
- IV and inhaled routes = rapid peak effect (30 secs - 2 mins) with duration 15-30 mins.
Pathophysiology
- Sodium channel blockade
resulting in:
- Local
anaesthesia
- Quinidine-like
effect with QRS widening and QTc prolongation
- In
high doses a direct toxic effect on the myocardium with
negative inotrope
- CNS stimulation through
activation of the sympathetic nervous system by blockade of
presynaptic reuptake of adrenaline, dopamine and serotonin (alpha
stimulation).
- Platelet aggregation
enhanced
Clinical Features
Cardiac
- Please see Cocaine Associated Chest Pain page
- Coronary vasoconstriction/spasm = acute coronary syndrome [Bestbets]
- Exacerbated by increased myocardial oxygen demand, smoking and enhanced platelet aggregation
- Ventricular arrhythmias
- Hypertension with risk of aortic dissection
CNS
- Severe hypertension and focal cerebral vasospasm (enhanced by lactic acidosis,
increased platelet aggregation and hyperpyrexia)
- Cerebral infarction or haemorrhage
- Euphoria and sense of alertness
- Occasionally acute psychosis
- Generalised complex epilepsy
Pulmonary
- Pulmonary ooedema - ? catecholamine mediated.
- Pneumonitis, asthma and bronchiolitis - due to immunological effects or due to
adulterants in cocaine.
- Barotrauma with smoking crack cocaine due to valsava manoeuvres thought to
enhance the drug effect
Renal
- Rhabdomyolysis-induced renal failure- exacerbated by vasoconstriction
Obstetric
- Increased risk of spontaneous abortion, placental abruption
- Intrauterine growth retardation - due to disruption of uteroplacental blood flow
due to vasoconstriction and maternal hypertension
Diagnosis
- Tachycardia, hypertension +/- arrhythmias
- Tachypnoea
- Hyperthermia
- Altered mental state leading to coma +/- fits
- Mydriasis
- Diaphoresis
- Consider occult trauma and associated drug use
Treatment
- Sedation with benzodiazepines which decrease central sympathetic outflow
- Management of cocaine associated chest pain
- Aggressive cooling for hyperthermia
- Aggressive fluid resuscitation to maintain urine output
- Treat seizures with benzodiazepines and further Rx as necessary
- Urgent CT brain for all seizures as high incidence of primary intracranial pathology
- Treat myocardial ischaemia with aspirin, nitrates and/or benzodiazepines [BestBets], heparin, opiates
- Β-blockers contraindicated (unopposed alpha stimulation worsens coronary and peripheral
vasoconstriction)
- Exclude myocardial injury in all cases of chest pain (see cocaine associated chest pain)
- Treat ventricular tachyarrhythmias and QTc prolongation with bicarbonate +/- magnesium
- Avoid anti-arrhythmics (including amiodarone)
- Avoid epinephrine if cardiac arrest occurs
- Treat severe hypertension with nitroprusside. (Avoid labetalol as despite alpha and beta blockade the predominant effect is beta-blockade.)
- Prolonged neuromuscular blockade occurs with suxamethonium due to acquired pseudocholinesterase deficiency. Blockade rarely lasts more than 20 minutes
- Body stuffers are people who swallow poorly packed cocaine to avoid arrest. Treatment is supportive as drug quantities are usually relatively small
- Body packers are people who ingest large quantities of well packed cocaine in order to smuggle it. Severe toxicity and even death occur if even 1 pack ruptures
- Asymptomatic - Conservative management [BestBets] with activated charcoal followed by whole bowel irrigation ("Klean-prep")with radiological imaging to ensure all packs are passed
- Symptomatic - supportive treatment and laparotomy. Endoscopy can result in pack rupture
