Author:  Donielle Sturgis, DO, MPH, Emergency Medicine Resident, PGY I

Faculty:  Alexis Cates, DO, Medical Toxicology/Emergency Medicine Attending

The Case:

A 33-year-old male presents to the emergency department accompanied by his girlfriend with a chief complaint of mouth sores.  He appears older than his stated age and very diaphoretic so he is immediately evaluated with vital signs in triage.  He’s found to have a heart rate of 120 bpm, a blood pressure of 162/96 mm Hg, and a temperature of 40°C.  The patient and his girlfriend are both sent back to a room where a full history and physical exam can be obtained.

At this point, the patient seems altered and not able to provide a clear history so his girlfriend provides the physician with the information.  She states that for the past 2 years, there has been a drastic change in his appearance and behavior.  He’s developed mouth sores and significant tooth decay.  She thinks that he may be using methamphetamines ever since they both tried it at a party one time.

Learning point 1:  Methamphetamine Toxicity

Methamphetamine is a sympathomimetic amine that belongs to the phenylethylamine group, and has a variety of stimulant, euphoric and hallucinogenic effects.  It was first synthesized in 1887 and used as a treatment for nasal congestion and asthma.  Recreational use of methamphetamine and other amphetamine-derived stimulants has reached epidemic proportions in the United States, Southern Asia, the Philippines, and Japan.  Approximately 5% of the US population has used methamphetamine in their lifetime, with an estimated 500,000 people using the drug in a given month.  It is the most widely abused illicit drug worldwide after cannabis.  

Methamphetamine is readily absorbed following administration via oral, pulmonary, nasal, intramuscular (IM), intravenous (IV) and vaginal routes.  It is lipophilic and readily crosses the blood brain barrier.  It is metabolized by CYP2D6 in the liver and eliminated renally.  The onset of action occurs within seconds after smoking or injection, and effects may be observed within 5 minutes after intranasal use or within 20 minutes following oral ingestion.  Peak plasma concentrations are achieved approximately 30 minutes following IV or IM administration and up to 2-3 hours after ingestion.  The plasma half-life of methamphetamine is 12-34 hours, and the duration of its effect commonly persists beyond 24 hours.

The clinical features of methamphetamine use are the result of their sympathomimetic, vasoconstrictive, psychoactive, and local anesthetic properties that affect a variety of organ systems.  Clinicians should consider the diagnosis of methamphetamine intoxication in any diaphoretic patient with hypertension, tachycardia, severe agitation, and psychosis.  The prognostic factors for mortality include coma, shock, body temperature >39°C, acute renal failure, metabolic acidosis, and hyperkalemia.  Methamphetamine users will have abrupt changes in behavior, becoming extraordinarily violent in severe acute intoxication.  Chronic users may appear malnourished, agitated, and disheveled.  Poor dentition with halitosis and accelerated age often occur.

Learning Point 2:  Work-up of Methamphetamine Intoxication in the Emergency Department

Laboratory values and imaging studies may vary depending on the clinical scenario of the intoxication.  

• Fingerstick glucose 
  • In order to rule out hypoglycemia as the cause of any alteration in mental status
•  Acetaminophen and salicylate levels 
  • Should be considered to rule out co-ingestion
• Complete metabolic panel
  • To evaluate renal function, electrolyte status and liver function tests
• Serum lactate 
• Creatinine kinase
  • Rhabdomyolysis is common following agitation
• Coagulation studies
  • To evaluate for synthetic liver dysfunction
• Troponin 
  • If there is concern for cardiac ischemia
• Pregnancy test
  • When of child-bearing age
• Urine drug screen 
  • To evaluate for other possible exposures
• EKG
  • To identify if any conduction abnormalities or dysrhythmias are present as a result of the intoxication or electrolyte distubances
• Imaging studies (Ex:  chest x-ray and/or echocardiogram, computed tomography for trauma)

Learning Point 3:  Treatment for Methamphetamine Intoxication 

Figure 1:  Methamphetamine Intoxication in Adults:  Rapid Review of Emergency Management, adapted from Up-to-date

• Control of agitation and hyperthermia comprise the core of the acute management of methamphetamine intoxication
  • Benzodiazepines are  first-line therapy for agitation and delirium
• If critical hyperthermia or agitation is not controlled, intubation and sedation with propofol and paralytics may be indicated
• Tachycardia can be treated with benzodiazepines
  • Reduces CNS catecholamine release
• Gastrointestinal decontamination with activated charcoal or whole bowel irrigation is rarely beneficial

Case Conclusion:

The patient was found to have a normal glucose level.  His UDS and confirmatory testing was positive for methamphetamines only.  The remainder of his work-up was unrevealing.  He was treated with benzodiazepines to control his tachycardia and hypertension and observed for several hours until he no longer had any apparent clinical effects of intoxication.  There were no significant lab abnormalities.  He was given dental follow-up for his profound dental caries as a result of methamphetamine misuse, as well as behavioral and addiction medicine follow-up.

References

Boyer, E. W., Siefert, S. A., & Hernon, C. (2019, December 24). Methamphetamine: Acute intoxication. UpToDate. https://www.uptodate.com/contents/methamphetamine-acute-intoxication?search=methamphetamine%20toxicity&source=search_result&selectedTitle=1~37&usage_type=default&display_rank=1#H9

Wightman, R. S., & Perrone, J. (2020). Chapter 187: Cocaine and Amphetamines. In Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 9e (pp. 1238-1242). McGraw-Hill Education. doi: 10.1097/MEJ.0b013e328355386b