eMedicine Specialties > Emergency Medicine > Toxicology

Toxicity, Methamphetamine: Treatment & Medication

Author: Robert Derlet, MD, Professor of Emergency Medicine, University of California at Davis School of Medicine; Chief Emeritus, Emergency Department, University of California at Davis Health System
Coauthor(s): Timothy E Albertson, MD, MPH, PhD, Professor of Pharmacology and Toxicology, Division Chief and Professor of Medicine, Division of Pulmonary and Critical Care Medicine, Vice-Chair, Department of Internal Medicine, University of California, Davis, School of Medicine; Professor of Anesthesiology, Associate Dean, Academic Clinical Programs, University of California, Davis Health System; Professor of Emergency Medicine and Clinical Toxicology, Davis Medical Center; Chief of Pulmonary and Critical Care, Veterans Affairs, Northern California Health Care System; Medical Director of Poison Control System, University of California at San Francisco, School of Pharmacy.
Contributor Information and Disclosures

Updated: Jul 10, 2008

Treatment

Prehospital Care

Patients with acute methamphetamine intoxication may be highly agitated and present a serious safety risk to prehospital personnel. Seek additional help from police or other EMS providers before patient transport, if possible. Prehospital IV access is warranted with patient consent, allowing for treatment of seizures and agitation using IV benzodiazepines according to medical direction or protocol.

Patient mental function may be sufficiently impaired, precluding the patient from making an informed decision to refuse treatment and transport.

Emergency Department Care

Most cases of amphetamine toxicity can be managed supportively. In the case of a severe overdose, immediate supportive care, including airway control, oxygenation and ventilation support, and appropriate monitoring is required. Specific treatments for heavy metal toxicity caused by contaminants in some methamphetamine preparations may be needed. Animal studies suggest that orally ingested but not IV amphetaminelike compounds can be decontaminated with oral activated charcoal. In severe overdoses, termination of amphetamine-induced seizure activity and arrhythmias are of immediate importance. Correction of hypertension, hypotension, hyperthermia, metabolic and electrolyte abnormalities, and control of severe psychiatric agitation are indicated. Consider health maintenance activities, such as testing for hepatitis and HIV disease.

• Agitation
  • Because of the ability of methamphetamine to cause significant CNS and psychiatric activation, patients who present to EDs for acute intoxication may require pharmacologic intervention.
  • Treat hyperactive or agitated persons with droperidol or haloperidol. Haloperidol and droperidol are butyrophenones and dopamine blocking agents that specifically antagonize the central behavioral effects of methamphetamine. Multiple clinical reports attest to the efficacy of droperidol and haloperidol in acute amphetamine toxicity.
    • An animal study has shown the superiority of haloperidol over diazepam in protecting against amphetamine-induced fatality.
    • Patients with acute choreoathetoid syndrome associated with amphetamines may show rapid improvement with haloperidol.
    • The doses of these medications should be titrated to the symptoms and be given IV (see Medication).
  • Diazepam, a benzodiazepine that enhances GABA neurotransmission (probably nonspecifically), affects methamphetamine-induced behavioral and psychiatric intoxication. It is also used to terminate amphetamine-induced seizures.
  • Diazepam was found to be highly effective in antagonizing the toxic effects of cocaine but not as effective against amphetamines in animal models. In a recent study of 146 patients presenting to the ED agitated, violent, or psychotic from methamphetamine, droperidol produced more rapid and profound sedation than lorazepam. Droperidol and lorazepam produced clinically significant reductions in pulse, systolic blood pressure, respiration rate, and temperature over a 60-minute period.
  • Significant social and psychiatric intervention is needed to reduce long-term dependency on amphetamines.
• Hypertension
  • If sedation fails, several antihypertensive agents, including short-acting IV beta-blockers or direct short-acting vasodilators, are effective in reversing some methamphetamine-induced hypertension.
  • Theoretically, IV labetalol would be the best agent because of combined anti–alpha-adrenergic and anti–beta-adrenergic effects. However, when given IV, labetalol loses much of its anti–alpha-adrenergic effect.
  • These drugs should be given in small IV doses and titrated to effect. However, clinical experience has shown labetalol and esmolol to be equally effective.
  • In rare instances, agents such as nitroprusside or fenoldopam are necessary.
• Myocardial infarction
  • The approach to the patient with methamphetamine-induced cardiac ischemia should be no different than in other cases. Nitrates, thrombolytics, beta-blockers, and other commonly used agents can also be used in the case of methamphetamine toxicity.
  • Carefully monitor blood pressure to ensure that it does not exceed contraindicated levels for thrombolytics.
  • Beta-blockers are very helpful in reducing oxygen demand because most patients have significant tachycardia.
• Seizures
  • Treat methamphetamine-induced seizures like other seizures of unknown etiology.
  • Administer benzodiazepines IV (see Medication).
  • In those patients who do not have IV access, an agent that has good IM absorption can be used (eg, lorazepam, midazolam).
  • After control of the acute episode, administer longer-acting stabilizing agents, such as phenobarbital.
  • All patients with methamphetamine-induced seizures are at high risk for intracranial bleeding and should receive a head CT scan as soon as possible.
• Rhabdomyolysis
  • Suspect rhabdomyolysis, and rule it out by drawing initial CK levels in patients who present to the ED with severe agitation from amphetamines.
  • Aggressively treat patients with rhabdomyolysis with fluids and admit them to the hospital.
  • Closely monitor renal function, vital signs, and fluid input and output.
  • Early and aggressive fluid and electrolyte treatment of potential rhabdomyolysis can improve the clinical outcome and decrease potential nephrotoxicity.

Consultations

Consult with a regional poison control center or a local medical toxicologist (certified through the American Board of Medical Toxicology and/or the American Board of Emergency Medicine) to obtain additional information and patient care recommendations.

Medication

The goals of pharmacotherapy are to reduce the toxic effects of the drug, reduce morbidity, and prevent complications.

GI decontaminant

Empirically used to minimize systemic absorption of the toxin.

Activated charcoal (Liqui-Char)

Most useful if administered within 4 h of ingestion. Repeat doses may be used, especially with ingestion of sustained release agents. Limited outcome studies exist, especially when administration is more than 1 h postingestion.
Administration of charcoal by itself (in aqueous solution), as opposed to coadministration with a cathartic, is becoming the current practice standard. This is because studies have not shown benefit from cathartics, and, while most drugs and toxins are absorbed within 30-90 min, laxatives take hours to work. Dangerous fluid and electrolyte shifts have occurred when cathartics are used in small children.
When ingested dose is known, charcoal may be administered at 10 times ingested dose of agent over 1 or 2 doses.

Benzodiazepines and other sedatives

By increasing the action of GABA, which is a major inhibitory neurotransmitter in the brain, benzodiazepines depress all levels of CNS, including limbic and reticular formation. Neuroleptic agents are useful for control of severely disturbed and/or violent patients.

Haloperidol (Haldol)

DOC for patients with acute psychosis when no contraindications are present. Parenteral dosage form may be admixed in syringe with 2-mg lorazepam for better anxiolytic effects. May be administered IM if unable to establish IV access.

Droperidol (Inapsine)

Somewhat faster-acting and more sedating than haloperidol but more likely to cause hypotension.
May exert antipsychotic activity through dopaminergic system. Evidence suggests that it alters dopamine action in CNS.
Administer IV in small boluses and titrate to effect. IM route may also be used if IV access is not yet established.

Diazepam (Valium)

Administered IV. Additional doses are titrated to effect. Less effective than the butyrophenones in controlling agitation.

Lorazepam (Ativan)

Sedative hypnotic with short onset of effects and relatively long half-life.
Benzodiazepine of choice in the ED. Can be given PO or SL (for rapid effect in panic attack) and IM or IV (mixed in the same syringe with the antipsychotic). Has longer CNS effects than diazepam and is preferred over antipsychotics for treatment of psychosis secondary to acute intoxication with hallucinogens, cocaine, PCP, and stimulants. Can be used as adjunctive therapy in nonorganic acute psychosis in which DOC is a high potency antipsychotic.
If given IM, may take 30-60 min to observe desired effect.

Midazolam (Versed)

Used as alternative in termination of refractory status epilepticus. Because water soluble, takes approximately 3 times longer than diazepam to peak EEG effects. Thus, clinician must wait 2-3 min to fully evaluate sedative effects before initiating procedure or repeating dose. Has twice the affinity for benzodiazepine receptors than diazepam. May be administered IM if unable to obtain vascular access.

Cardiovascular agents

Used to control catecholamine-induced hypertension.

Labetalol (Normodyne, Trandate)

Blocks beta1-, alpha-, and beta2-adrenergic receptor sites, decreasing blood pressure. When given IV, acts primarily as a beta-receptor antagonist.

• Search for CME/CE on This Topic »

• Toxicity, Sympathomimetic (Emergency Medicine)
• Stimulants (Psychiatry)
• Toxicity, Lidocaine (Emergency Medicine)
• Toxicity, Mercury (Emergency Medicine)

• Activated Charcoal
• Poisoning - First Aid and Emergency Center
• Mental Health and Behavior Center
• Substance Abuse Center
• Drug Dependence and Abuse Overview
• Poisoning Overview
• Club Drugs Introduction
• Substance Abuse Overview

• Serotonin Toxicity, ECG Abnormalities Seen With Escitalopram Overdose
• Genetically Diverse Mouse Panel Predicts Individual Variability in Drug Toxicity
• "Substantial" Toxicity With Peginterferon Use: FDA Staff

• The Clinical Pharmacology of Intranasal l-Methamphetamine
• Bottoms Up: Methamphetamine Toxicity From an Unusual Route
• Myocardial Infarction Associated With Adderall XR and Alcohol Use in a Young Man