d-methamphetamine

CAS RN: 537-46-2

Treatment Overview

0.4.2 ORAL EXPOSURE
  • A) MANAGEMENT OF MILD TO MODERATE TOXICITY
    • 1) Most amphetamine related toxicity may be safely managed with supportive care that includes monitoring airway, breathing, and circulation, and control of agitation with benzodiazepines. Intravenous fluids may be needed for mild dehydration, and sedation for agitation. Charcoal may be indicated if recent ingestion, airway controlled, and low seizure risk.
  • B) MANAGEMENT OF SEVERE TOXICITY
    • 1) Severe agitation requires aggressive treatment to avoid malignant hypertension, rhabdomyolysis, hyperthermia, and seizures. Large doses of benzodiazepines may be needed. Severe cases may require neuromuscular paralysis, intubation, and active cooling measures. For tachycardia, treat with intravenous fluids, sedation. For severe hypertension unresponsive to sedation, consider IV nitroprusside. Rhabdomyolysis is best treated with adequate 0.9% normal saline; monitor CK, electrolytes, and creatinine. Diuretics and urinary alkalinization are not recommended. Ventricular dysrhythmias should be treated with standard ACLS protocols.
  • C) DECONTAMINATION
    • 1) PREHOSPITAL: Not recommended because of potential for agitation, seizures.
    • 2) HOSPITAL: Activated charcoal binds amphetamines. For oral exposures, consider charcoal administration if patient is able to drink safely, low risk for seizures.
  • D) AIRWAY MANAGEMENT
    • 1) Intubate if unable to protect airway, to control agitation, hyperthermia, and status epilepticus.
  • E) ANTIDOTE
    • 1) None
  • F) PSYCHOMOTOR AGITATION
    • 1) Sedate patient with benzodiazepines as necessary; large doses may be required.
  • G) HYPERTENSIVE EPISODE
    • 1) Consider IV nitroprusside for severe hypertension unresponsive to sedation. DOSE: Start at 0.5 to 1 mcg/kg/min and titrate as needed.
  • H) ENHANCED ELIMINATION
    • 1) Hemodialysis and hemoperfusion are not useful because of the large volume of distribution.
  • I) PATIENT DISPOSITION
    • 1) HOME CRITERIA: Inadvertent ingestions in asymptomatic patients, and pediatric exposures of commercial pharmaceutical agents within published pediatric therapeutic dose, who have no synergistic co-ingestions, may be monitored at home.
    • 2) OBSERVATION CRITERIA: Patients with deliberate ingestions, synergistic co-ingestions, unclear history, symptomatic or intoxicated patients, exposure to doses outside published therapeutic ranges, or those in unstable social situations should be sent to a healthcare facility for observation.
    • 3) ADMISSION CRITERIA: Patients with persistent or worsening vital sign abnormalities, continued or difficult to control agitation or psychosis, multiple seizures, cardiac ischemia, or dysrhythmias should be admitted. Intensive care unit is indicated for aggressive airway or cardiac monitoring.
    • 4) CONSULT CRITERIA: Consult a poison center or medical toxicologist for assistance in managing patients with severe toxicity (ie, progressive agitation, psychosis, dysrhythmias, malignant hypertension, hyperthermia), concerns about decontamination, or in whom the diagnosis is unclear.
  • J) PITFALLS
    • 1) Drug effect may be prolonged, requiring extended observation times or admission until symptoms resolve. Prolonged toxicity may develop after ingestion of sustained-release formulations. Other complications of drug abuse may be present (eg, trauma, infection).
  • K) PHARMACOKINETICS
    • 1) Most amphetamines are well absorbed from the gastrointestinal tract. Peak plasma levels occur in about 2 to 3 hours after oral amphetamine exposure. Amphetamine protein binding is approximately 16%. Volume of distribution for amphetamine is 3.2 to 5.6 L/kg. Amphetamine is hepatically metabolized by hydroxylation and n-dealkylation pathways. P-hydroxyamphetamine, a potent hallucinogen, is a major metabolite of amphetamine. Non-metabolized amphetamine is excreted in the urine. Duration of effect varies depending on agent and urine pH. Excretion is enhanced in more acidic urine. Half-life is 7 to 34 hours and is, in part, dependent on urine pH (half-life is longer with alkaline urine).
  • L) DIFFERENTIAL DIAGNOSIS
    • 1) Cocaine intoxication, phencyclidine (PCP) toxicity, anticholinergic poisoning, sepsis, encephalitis, trauma. In pediatric population, also consider scorpion envenomation, intussusception, meningitis, and sepsis.
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