Fast Five Quiz: Drug Overdoses

Richard H. Sinert, DO

Disclosures

October 23, 2019

Acute and long-term methamphetamine use may lead to abnormal findings on examination of the following organ systems:

  • Cardiovascular

  • CNS

  • Gastrointestinal

  • Renal

  • Skin

  • Dental

There are specific cardiovascular findings associated with acute and long-term methamphetamine use:

  • Tachycardia and hypertension is frequently observed

  • Atrial and ventricular arrhythmias may occur

  • Chest pain from cardiac ischemia and infarction following methamphetamine use has been reported, and patients are at risk because of accelerated atherosclerosis from chronic use; acute aortic dissection or aneurysm has been associated with methamphetamine abuse

  • Hypotension may be observed with methamphetamine overdose with profound depletion of catecholamines

  • Acute and chronic cardiomyopathy results directly from methamphetamine cardiac toxicity and indirectly from chronic hypertension and ischemia; intravenous use may result in endocarditis; patients may have dyspnea, edema, and other signs of acute congestive heart failure exacerbation

The euphoric effects produced by methamphetamine, cocaine, and various designer amphetamines are similar and may be difficult to clinically differentiate. A distinguishing clinical feature is the longer pharmacokinetic and pharmacodynamic half-life of methamphetamine, which may be as much as 10 times longer than that of cocaine.

Methamphetamine can cause significant CNS and psychiatric activation, so patients who present to emergency departments for acute intoxication often require physical restraint and pharmacologic intervention. Hyperactive or agitated patients can be treated with droperidol or haloperidol, which are butyrophenones that antagonize CNS dopamine receptors and mitigate the excess dopamine produced from methamphetamine toxicity. These medications should be administered intravenously, with doses adjusted based on the symptoms. Droperidol has been subject to a black box warning by the US Food and Drug Administration based on concerns of QT prolongation and the potential for torsades de pointes. As a result, some institutions restrict its use. However, it is important to note that the black box warning specifies dementia-related psychosis and is not supported by the literature for doses below 2.5 mg.

If sedation fails to reduce blood pressure, antihypertensive agents such as beta-blockers and vasodilators are effective in reversing methamphetamine-induced hypertension and tachycardia. With regard to choice of beta-blockers, labetalol is preferred because of its combined anti–alpha-adrenergic and anti–beta-adrenergic effects. Labetalol has been shown to safely lower mean arterial pressure in patients with positive cocaine test results. Carvedilol, like labetalol, is a nonselective beta-blocker with alpha-blocking activity and may also be effective for this indication. Esmolol is advantageous because of its short half-life but must be administered via intravenous drip. Metoprolol has excellent CNS penetration characteristics and may also ameliorate agitation.

Read more about methamphetamine toxicity.

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