Amphetamine (“TIK”) toxicity

Mechanism of toxicity
Toxic dose
Symptoms and signs of acute poisoning
Special investigations
Management

Mechanism of toxicity

Potent central cortical and peripheral sympathetic nervous system stimulator.

Toxic dose

Dose response variable as chronic amphetamine abusers develop tolerance.

Symptoms and signs of acute poisoning

• General: diaphoresis, flushing, mydriasis, hyperthermia
• Central nervous system: agitation, hyperactivity, confusion, delirium, hallucinations, seizures, intracranial haemorrhage, stroke, coma
• Musculoskeletal: rigidity, fasciculations, rhabdomyolysis
• Cardiovascular: chest pain, acute coronary syndrome, hypertension, tachycardia, palpitations, dysrhythmias
• Gastrointestinal: nausea, vomiting, diarrhoea

Special investigations

• No specific investigations required in patients with mild toxicity
• Qualitative (reported as negative or positive) urine amphetamine to confirm diagnosis
• In severe toxicity, consider: ECG, electrolytes, creatinine, CK, troponin as guided by clinical picture

Management

Symptomatic and supportive:

• Convulsions: convulsions can be controlled by slow IV administration of diazepam.
• Hypertension: transient and generally do not require treatment. Sedation with benzodiazepines often sufficient.
• Agitation and psychosis: benzodiazepines agent of choice as haloperidol may lower seizure threshold and is associated with neuroleptic malignant syndrome.