What medication should be given to a patient with acute methamphetamine intoxication?

Management of Acute Methamphetamine Intoxication

For patients with acute methamphetamine intoxication, benzodiazepines are the first-line treatment for agitation, hypertension, and tachycardia, either alone or in combination with nitroglycerin. 1, 2

Initial Approach to Agitation and Sympathetic Hyperactivity

• Administer benzodiazepines immediately as they address both central and peripheral manifestations of acute methamphetamine intoxication, including hypertension, tachycardia, and agitation. 1, 2

• Lorazepam 0.5-1 mg IV/IM can be given every 30-60 minutes as needed for agitation (maximum 4 mg in 24 hours for adults). 1

• Midazolam 2.5-5 mg subcutaneously every 2-4 hours is an alternative if the patient cannot swallow or IV access is difficult. 1

• Benzodiazepines work by reducing the central sympathetic outflow and peripheral catecholamine effects without the risk of unopposed alpha-adrenergic stimulation. 1, 2

Management of Hypertension and Tachycardia

• Combine benzodiazepines with nitroglycerin if hypertension persists after benzodiazepine administration alone. 1, 2

• Phentolamine (an alpha-blocker), nicardipine, or nitroprusside can be considered if additional blood pressure control is needed beyond benzodiazepines and nitroglycerin. 1

• Clonidine is an alternative option that provides both sympathicolytic and sedative effects. 1

Management of Chest Pain and Suspected Coronary Vasospasm

• Start with benzodiazepines as first-line therapy for methamphetamine-associated chest pain. 2

• Add nitroglycerin to benzodiazepines for coronary vasodilation. 2

• Calcium channel blockers (diltiazem or verapamil) are specifically indicated for coronary vasospasm associated with methamphetamine use. 2

• Administer aspirin and anticoagulation (unfractionated heparin or low-molecular-weight heparin) unless contraindicated, as methamphetamine increases platelet aggregation. 2

Critical Medications to AVOID

• NEVER administer beta-blockers (including labetalol) to patients showing signs of acute methamphetamine intoxication (euphoria, tachycardia, hypertension). 1, 2

• Beta-blockers are absolutely contraindicated because methamphetamine stimulates both alpha- and beta-adrenergic receptors; blocking beta receptors leaves unopposed alpha-adrenergic stimulation, which worsens coronary vasospasm and hypertension. 1, 2

• This contraindication applies during the acute intoxication phase; beta-blockers may be used once signs of acute intoxication have resolved. 1

Management of Severe Agitation Requiring Chemical Sedation

• For patients with medical/intoxication-related agitation, benzodiazepines are preferred first-line; consider adding a first-generation antipsychotic (haloperidol) only if benzodiazepines alone are insufficient. 1

• Droperidol produces more rapid and profound sedation than lorazepam for methamphetamine toxicity, though it requires more careful monitoring for extrapyramidal symptoms. 3

• Haloperidol 5-10 mg IM can be added to benzodiazepines for severe agitation, repeated every 20-30 minutes as needed. 1

Management of Psychosis

• Most methamphetamine-induced psychosis is self-limiting and resolves within 24 hours without specific antipsychotic treatment. 4

• Benzodiazepines alone are often sufficient for managing acute behavioral disturbance associated with psychosis. 4

• Antipsychotics (haloperidol) should be reserved for cases where benzodiazepines fail to control severe agitation or psychotic symptoms persist beyond the acute intoxication phase. 1

Common Pitfalls to Avoid

• Failing to recognize signs of acute intoxication before administering beta-blockers is the most dangerous error and can result in fatal coronary vasospasm. 2

• Administering beta-blockers before vasodilators in methamphetamine-induced hypertension or chest pain. 2

• Using diltiazem in patients with heart failure with reduced ejection fraction due to negative inotropic effects. 2

• Combining diltiazem with beta-blockers increases risk of bradycardia and heart block. 2

• Underestimating the duration of observation needed: most patients require 15-20 hours in a short-stay unit for complete resolution of symptoms. 4

Disposition and Follow-up

• Most patients with acute methamphetamine intoxication can be managed in the emergency department or short-stay unit, with median length of stay around 15 hours. 4

• Only 4% of presentations require psychiatric admission for persistent psychotic symptoms. 4

• Complete resolution of psychotic symptoms occurs in 83% of cases within the ED observation period. 4