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Amphetamines as a class may be abused by ingestion, insufflation (“snorting”), parenteral injection, and smoking. “Ice” refers to a pure preparation of methamphetamine hydrochloride in a large crystalline form. Designer amphetamines include 3,4-methylenedioxymethamphetamine (MDMA, “ecstasy”), paramethoxyamphetamine (PMA), and synthetic cathinones (ingredients in “bath salts”). While the central nervous system (CNS) targets of these compounds are serotonergic and dopaminergic pathways, the clinical presentation is manifested as a sympathomimetic toxidrome.
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Although clinically indistinguishable from cocaine toxicity, the duration of effects is appreciably longer. The most common cardiovascular manifestations of toxicity are tachycardia and hypertension, although myocardial ischemia has been reported. Despite the cardiovascular effects, CNS toxicity is the primary reason most amphetamine users present for medical care. Presentations may range from increased anxiety to life-threatening agitated delirium with hyperthermia. Visual and tactile hallucinations and psychoses are common. Poor dentition is common among chronic users (“meth mouth”), and appears multifactorial in nature.
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Management and Disposition
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Treatment focuses upon the signs and symptoms of toxicity. As with other causes of sympathomimetic toxicity, initial management includes control of the agitation to prevent other complications (eg, rhabdomyolysis). Benzodiazepines are the first-line therapy for agitation; large repeated doses may be required. Severe hyperthermia requires evaporative cooling techniques. Hypertonic sodium may be useful for MDMA-associated cerebral edema and seizures.
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In addition to the medical complications associated with methamphetamine use, the manufacture of methamphetamine is associated with exposure to a number of toxic chemicals and risk for severe burns.
The hyperthermia associated with acute amphetamine poisoning may result in end-organ damage similar to patients with heat-stroke-like illness.
MDMA may result in syndrome of inappropriate antidiuretic hormone (SIADH) with subsequent hyponatremia and cerebral edema.
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NEW DESIGNER DRUGS: “BATH SALTS” AND “SPICE”
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