MDMA Toxicity: Practice Essentials, Background, Pathophysiology

MDMA is a member of a family of amphetamine derivatives known as MDA. Structurally, MDMA is similar to the stimulant methamphetamine and the hallucinogen mescaline. Like other amphetamines (in particular, dopamine and norepinephrine), it causes catecholamine release from presynaptic vesicles. However, MDMA also is a selective serotonergic neurotoxin that causes massive release of serotonin (ie, 5-hydroxytryptamine [5-HT]) and is postulated to inhibit its uptake. In animal models, it has been demonstrated to cause long-term destruction of 5-HT axons and axon terminals [7, 8, 9] . No randomized clinical human studies exist, and one always must be cautious when extrapolating animal study data and applying it to human models. However, studies demonstrate lowered concentrations of the 5-HT metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the cerebrospinal fluid of regular MDMA users. This correlates with a similar decrease reported in primates with brain damage induced by MDMA.

The effects of MDMA can be described as those of a hallucinogenic amphetamine, combining some effects of amphetamine (ie, "speed") with that of LSD (ie, "acid"). However, many of the effects are dose dependent, and auditory and/or visual hallucinations are not commonly observed. Much of the abuse potential lies in its pleasurable subjective effects (eg, empathy, euphoria, disinhibition, increased sensuality); MDMA is often described as the “hug drug,” due to the amplified desire to be touched and socialize.

MDMA is available as a tablet, capsule, powder, and liquid; however, it most commonly is used in capsule or tablet form. The pure crystalline powder form of MDMA is usually sold in capsules and is popularly known as Molly (slang for “molecular”). [10] Tablets often are engraved with various motif symbols and brands, ranging from birds (eg, doves) and animals (eg, blue elephants), numbers (eg, 8 1/2), cartoon characters (eg, Bugs Bunny), and cars (eg, Ferrari).

MDMA is usually swallowed, although reports of smoking, snorting, and injecting MDMA have been found. Users may place a crushed or powdered dose of MDMA in a small piece of soft paper (eg, toilet paper) and swallow it—so-called parachuting—to speed onset of the drug's effect. [11] Following oral intake, the duration of action is 8-24 hours with a half-life of 12-34 hours, though this can depend on the purity of the drug ingested.

About 75% is excreted unchanged by the kidneys; the rest is metabolized in the liver, specifically by the liver enzyme CYP2D6 and catechol–O–methyl transferase (COMT). [12] Of note, a small subset of the population has a CYP2D6 genotype that results in absent or low CYP2D6 enzyme activity, or a COMT genotype that results in low COMT enzyme activity. Decreased enzyme function may also be due to inhibition from medications such as the protease inhibitor ritonavir, which may be implicated in severe toxicity such as serotonin syndrome, hepatitis, disseminated intravascular coagulation, hyponatremia, and fatalities caused by the inability to metabolize MDMA. [13]

Typically, a tablet contains approximately 50-100 mg of MDMA and costs approximately $20-25. Effective doses are 1-2 mg/kg, and initial effects occur in 30-60 minutes. Peak effects occur at 90 minutes and may persist 4-8 hours. Tolerance to the psychoactive properties of MDMA develops rapidly, and an increase in adverse effects is reported because of frequent use. Repeated doses cause sympathomimetic responses to predominate and can result in amphetamine-like toxicity. Severe hyperthermia has been reported at doses of 4-5 mg/kg.

One of the problems in assessing the causes and effects of MDMA toxicity is determining the purity of the ingested substance. Synthesis of MDMA is relatively simple, and it often is produced in illicit laboratories or clandestine locations, such as basements and garages. In addition to the less than ideal quality control measures, these synthesized tablets also may be cut or mixed with other psychoactive substances. Substances found mixed with MDMA have included heroin, ketamine, and ephedrine (ie, herbal ecstasy).

General medical adverse effects

The acute effects of MDMA have an initial onset of 30 minutes after oral intake and are characterized by anxiety, tachycardia, and elevated blood pressures. Associated symptoms include diaphoresis, bruxism, jaw clenching, paresthesias, dry mouth, increased psychomotor activity, and blurred vision. Within 1 hour, these sympathomimetic effects are replaced by feelings of relaxation, euphoria, and increased empathy and communication. While overt auditory and/or visual hallucinations are uncommon, patients report increased sensory tactile enhancement and mild visual distortions, such as halos. These effects plateau for up to 90 minutes and then diminish over 3-4 hours.

Many users attempt to prolong these effects by taking additional doses of the drug. However, when too much additional MDMA is consumed in a single session, individuals report unpleasant symptoms of autonomic hyperarousal associated with feelings of restlessness, paranoia, and anxiety. Tolerance to the psychoactive properties of MDMA develops rapidly, and the user is unable to restore the euphoric effects with repeated doses. Instead, sympathomimetic effects predominate, placing the patient at risk for cardiovascular instability, arrhythmias, and hyperthermia.

In addition, following the acute effects of MDMA, users often report a 24- to 48-hour period characterized by lethargy, anorexia, and dysphoria. This period of lethargy is known as the blues or colloquially “suicide Tuesday” after weekend ecstasy use and is dangerous because other drugs often are co-ingested to help ease the "crash" after psychostimulant administration.

Cardiovascular effects

Autonomic hyperactivity is a major feature in patients presenting with MDMA toxicity and is dose-dependent. Typically, MDMA has only 1/10 the CNS stimulant effect of amphetamine. The proposed mechanism is the amphetamine-induced catecholamine and 5-HT surge that causes tachycardia, hypertension, and hyperthermia. Hyperthermia is especially dangerous because many cases involve patients dancing for prolonged periods with inadequate fluid intake in crowded dance halls with hot temperatures and poor ventilation.

As with any amphetamine, the risk of cardiac dysrhythmias and cardiovascular collapse is always a possibility. Fatal dysrhythmias have been reported following MDMA use, resulting in ventricular fibrillation and asystole. Individuals with underlying cardiac and/or pulmonary disease and preexisting conditions such as Wolff-Parkinson-White syndrome are especially at risk for heart failure and fatal arrhythmias.

Serotonin syndrome

Serotonin syndrome is a condition in which central 5-HT receptor hyperstimulation results in classic findings of hyperthermia, mental status changes, autonomic instability, and altered muscle tone and/or rigidity. MDMA causes massive serotonin release, and numerous case reports link MDMA toxicity to the serotonin syndrome. [13, 7] The mechanism is unclear, but a direct effect by MDMA on the thermoregulatory centers may be potentiated by sustained physical activity, high temperatures, and inadequate fluid intake as observed at rave parties. Vigorous dancing for long hours in these conditions can predispose patients to hyperthermia, dehydration, and muscle breakdown leading to rhabdomyolysis. [14] Further complications include disseminated intravascular coagulation (DIC), hepatotoxicity, and acute kidney injury. [15] Most cases of toxicity have been idiosyncratic and did not depend on massive overdoses.

Hyponatremia

Various cases of seizure and death secondary to hyponatremia have been reported. The occurrence of hyponatremia after MDMA use is multifactorial, stemming from increased water intake, excessive sweating with physical exertion, and the release of vasopressin leading to the syndrome of inappropriate antidiuretic hormone secretion (SIADH). [16, 17] In severe cases of hyponatremia, patients can develop cerebral edema with subsequent seizures and, possibly, coma. These patients invariably show high urine osmolarity and continued sodium excretion despite low serum osmolality and hyponatremia, which is consistent with the criteria for diagnosis of SIADH. In the ED, always consider hyponatremia with resultant cerebral edema in any patient with known MDMA ingestion who presents with an altered mental status or seizure.

Neurologic effects

MDMA, like other amphetamines, can lead to a variety of potentially fatal neurologic outcomes, including subarachnoid hemorrhage, cerebral infarction, or intracranial bleeds. Underlying mechanisms involve the short-term hypertensive surges and subsequent disruption of cerebral blood vessels, especially in patients with congenital arteriovenous malformations or cerebral angiomas. While these fatalities are rare, always consider amphetamine use as a possible cause of stroke.

Hepatotoxicity

Growing evidence suggests that MDMA may harm the liver. Hepatotoxicity ranges from asymptomatic liver injury with confirmation of elevation of the liver function tests to fulminant acute hepatic failure. Different patterns of liver injury are recognized, including benign lesions, viral hepatitis, extensive or focal hepatic necrosis, total loss of liver parenchyma and function with accompanying encephalopathy, cerebral edema, and multiorgan system failure.

In the setting of grade III or IV hepatic encephalopathy, without a liver transplant, the mortality rate is more than 50%. The presentation of MDMA hepatotoxicity varies. The timing of ingestion and onset of symptoms, as well as doses, do not seem to correlate with the clinical severity, and recurrence can also occur due to chronic use. Chronic use of MDMA leads to fibrotic changes that are related to an increase of collagen I production by the stellate cells.

Histopathologically, hepatotoxicity associated with hyperthermia demonstrates a picture of centrolobular necrosis and microvesicular steatosis. Without hyperthermia present, hepatotoxic changes noted are consistent with acute cholestatic hepatitis with eosinophils and macrophage infiltrates. The reasons for the different patterns of injury are still not completely understood, although theories include hyperthermia, increased efflux of neurotransmitters, oxidation of biogenic amines, mitochondrial impairment, apoptosis, and genetic polymorphisms. [18]

CYP2D6 catalyzes the metabolism of MDMA in the liver via O-demethylenation pathway. So atypical responses to MDMA may be related to genetic polymorphisms of this isoenzyme. Subjects known to be slow metabolizers had elevated levels of MDMA and lower levels of the demethylenated product after being administered two 100-mg doses with a 24-hour interval period in a clinical trial. Clinically, a slow metabolizer may be at greater risk for developing acute MDMA toxicity.

Finally, MDMA is synthesized, and often the source as well as well as the purity of the drug is unknown. One must consider whether the liver toxicity was caused by MDMA, another psychoactive compound contained in the ecstasy tablet, a contaminant, or coingestion of another drug. Nevertheless, MDMA may exert harmful effects on the liver and may cause significant damage, especially when combined with other hepatotoxic substances.

Long-term neuropsychiatric effects

The literature suggests the possibility of long-term psychiatric complications involving regular use of MDMA. The long-term effects may be related to the decrease in serotonin reuptake transporter (SERT) function and numbers. Recovery of SERT may take weeks and months; ultimately, persistent use may lead to permanent serotonergic damage of the axons and terminals sparing the cell bodies. Patients have reported symptoms of depression, anxiety, panic attacks, and insomnia after ending MDMA use. Further studies report that patients using MDMA have difficulty concentrating and short-term memory impairment. [19] Although much of the focus in the ED involves managing the acute toxic effects of MDMA, educate patients that long-term neurologic and psychiatric complications may occur.