Epidemiology

Recreational abuse of hallucinogens and other drugs is common among patients in the emergency department (ED) and is directly responsible for many ED visits. Although the exact prevalence of drug abuse in patients in the ED is unknown because so much drug abuse goes undetected, various surveillance studies all indicate that ED visits related to drug use continue to rise yearly.^1–3

Patients who present to an ED immediately after using a drug do so for various reasons: an unfavorable or unanticipated reaction to the drug, an unintentional overdose, a traumatic injury, altered mental status, or suicidal and other dangerous behavior. In addition to the acute complications directly related to drug use, many cardiovascular, neurologic, infectious, psychiatric, and social health problems treated in the ED are linked to chronic drug abuse. Because drug abuse is often not declared by the patient at the time of arrival, recognition and optimal treatment require vigilance from the emergency physician, as well as attention to historical, clinical, and laboratory clues.

Recreational drug use today knows no demographic, age, or socioeconomic boundaries. Drug use is just as common (although perhaps less frequently suspected) in white, employed, and insured individuals as in patients who are nonwhite, unemployed, or homeless.^1,4 In the last 2 decades, first-time drug use has become more common among adolescents, and the variety of drugs used has exploded.^5,6 Drug use is no longer limited to what can be identified on a standard hospital toxicology screen, and many of the drugs people abuse to become high are not illegal, such as cough and cold products and prescription medications.^7–10 The rampant growth of drug use is likely linked to the proliferation of the Internet and the wide availability of unregulated partisan drug sites that enable potential users to learn about drugs, to order the raw ingredients and supplies to manufacture their own drugs, or simply to purchase drugs online in the safety of their own homes.⁶

Pathophysiology

The drugs available for recreational abuse are countless and are constantly evolving. In the past, recreational drugs were categorized, for the purposes of discussion, identification, and treatment, somewhat arbitrarily on the basis of structural class, predominant biochemical or neurotransmitter activity (e.g., dopaminergic versus serotonergic versus gamma-aminobutyric acid [GABA]–ergic), or expected clinical effect (e.g., hallucinogen versus stimulant versus entactogen). In reality, most drugs exhibit multiple biochemical effects of varying intensity that are not limited to a particular structural class, and clinical findings vary widely among different individuals even when these persons are exposed to the same drug. Physicians now recognize that clinical variability depends not only on the specific type of drug but also on the dose used, the form of drug (e.g., crystal versus powder versus liquid), the purity of the drug, the route of delivery (e.g., intranasal versus ingestion versus injection), the concomitant use of coingestants, individual genetic polymorphisms, and individual biochemical and physiologic adaptations from long-term exposure.

Most recreational drugs are highly lipophilic and easily cross the blood-brain barrier, so most result in some euphoria; otherwise, patients would have little reason to abuse them.³ Although the exact mechanisms are still incompletely understood, modulation of central dopaminergic activity, which is responsible for pleasure seeking and reward reinforcement, is an important factor in the euphoric response and the development of drug addiction.³ Recreational drugs also affect, to variable extents, peripheral and central norepinephrine, serotonin (5-HT), N-methyl-D aspartate (NMDA), and GABA activity.

Presenting Signs and Symptoms

The most common presenting feature in all patients with recreational drug use is some degree of altered mental status. It may range from seemingly benign giddiness to life-threatening agitation or obtundation. Drug-associated altered mental status may be associated with any kind of vital sign abnormalities or evidence of end-organ damage. Cardiovascular, neurologic, infectious, and psychiatric complaints are also common (Table 150.1). Because the predominant drugs seen in a particular ED vary depending on local geographic preferences and because the types of drugs abused change far more quickly than published medical literature can keep up with, optimal treatment depends on symptom-based (rather than drug-based) diagnostic strategies and interventions.

Table 150.1 Signs and Symptoms of Recreational Drug Use

Amphetamine