By Ruby Nguyen, Music and Neurobiology, Physiology, and Behavior, ‘19

Author’s note: I wrote this literature review for UWP104F, Writing for Health Professions. The assignment was to write a literature review on a health-related topic of our choosing. I decided to write this literature review on ecstasy-induced hyperthermia, the primary cause of death in ecstasy overdoses. I want to inform researchers on potential drug options or treatments that could be further explored for use in treating ecstasy-using patients. I also want to reveal areas for further consideration. My hope is that this literature review will spark greater interest on the topic and guide future research into exploring new treatment options for ecstasy-induced hyperthermia.

Abstract

Background: Ecstasy-induced hyperthermia is a public health concern that plagues the music scene. Few studies exist that evaluate mechanisms and treatment options for hyperthermia. These mechanisms and treatment options are complex and expansive, and little research has been conducted to fully evaluate our understanding of the disease.

Aim: The aim of this literature review is to provide a comprehensive evaluation of ecstasy-induced hyperthermia by describing, summarizing, and comparing current literature on the topic. This literature review hopes to guide future research into treatment options for ecstasy-induced hyperthermia.

Results: Ecstasy-induced hyperthermia was found to be a result of two processes in the body: thermogenesis via UCP-3 uncoupling, and vasoconstriction via multiple mechanisms. These processes are complex, and this literature review provides a general overview of pathways involving hyperthermia. Treatment options were evaluated from animal studies and case studies conducted on humans. The results of this review show that few drug options exist for humans. Current palliative options for treating ecstasy-induced hyperthermia have also been shown to be largely ineffective in attenuating the disease.

Conclusions: The findings of this literature review show that potential and new drug candidates should be evaluated for use in treating ecstasy-induced hyperthermia in humans. The results also indicate a number of new palliative options for treating ecstasy-induced hyperthermia, including new cooling methods and surgical interventions.

Keywords

Ecstasy, MDMA, 3-4-Methylenedioxymethamphetamine, Hyperthermia, Hyperpyrexia, Thermogenesis, Temperature management, Treatment, SSO, Clozapine, Carvedilol, THC, Cooling, Fasciotomy, Cervical sympathectomy, Multiorgan support, Literature review

Introduction

For decades, psychoactive stimulants have been used to enhance musical experiences. One of the most commonly abused of these stimulants is the illegal substance ecstasy, also known as 3,4-Methylenedioxymethamphetamine or MDMA. Ecstasy has become the quintessential party drug for concert-goers across the United States (6). In a case study of a rave event in San Francisco, twelve patients were admitted to the hospital for complications arising from ecstasy use, with two succumbing to death (2). Many of these deaths were a consequence of organ failure as a result of ecstasy-induced hyperthermia, or overheating of the body (1). Ecstasy has become a public health concern that plagues the live music scene, and will continue to be a problem for the foreseeable future.

This literature review will evaluate the current state of knowledge on ecstasy-induced hyperthermia. Because ecstasy is a difficult substance to acquire and test for research purposes, much of this knowledge will come from research conducted on animal models. However, results from these experiments will reveal potential mechanisms of hyperthermia in humans, and implicate treatment options that should be investigated by medical researchers. The next section of this literature review will describe these mechanisms to provide background on how hyperthermia is induced. These mechanisms will describe major pathways that are currently targeted by drug options to alleviate hyperthermia. The discussion section at the end of this literature review will describe areas of consideration for medical researchers, using our current understanding of the mechanisms of hyperthermia and gaps in our current knowledge to guide medical researchers on potential targets and pathways of interest. This literature review will thus provide a comprehensive background on the mechanisms and treatment options for ecstasy-induced hyperthermia, and guide future research to combat this public health concern.

Mechanisms of Ecstasy-Induced Hyperthermia

Hyperthermia is an adverse effect that presents following ecstasy consumption. However, there is no one pathway that characterizes hyperthermia in its entirety. The following sections will describe the currently understood mechanisms of ecstasy-induced hyperthermia. Although many of these mechanisms were determined using animal models, these mechanisms give valuable insight into potential mechanisms of human thermogenesis.

Vasoconstriction via the 5-HT pathway modulates thermogenesis

In an early study to investigate the mechanisms of ecstasy-induced hyperthermia, Pedersen and Blessing (2001) measured changes in cutaneous blood flow in rabbits to elucidate whether hyperthermia was a result of increased or decreased blood flow in the body. The researchers administered ecstasy and measured “blood flow, pressure, and temperature signals,” (13, p. 8649) as well as heart rate, using a probe inserted into the rabbits (13). Rabbits underwent unilateral cervical sympathectomies and the blood flow in each ear was compared (13). Heart pressure was observed to have increased, with no change to heart rate (13). In addition, the unilateral cervical sympathectomy was shown to increase blood flow in the ear and minimize the effects of hyperthermia (13). These findings suggested that vasoconstriction was the primary cause of hyperthermia in the rabbits (13). These findings also pointed to the influence of the sympathetic nervous system on vasoconstriction and thus hyperthermia in the rabbits (13). Previous studies, conducted by Blessing and Nalivaiko (2000), found that 5-HT (serotonin) released from “raphe magnus-pallidus neurons” (4, p. 289) acted upon 5-HT2A receptors in the spine, leading to vasoconstriction in rabbits (12; 13). Pedersen & Blessing (2001) thus hypothesized that ecstasy stimulated the release of 5-HT to activate 5-HT2A receptors on the “perikarya and dendrites of preganglionic sympathetic cutaneous vasomotor neurons,” (13, p. 8653) leading to the vasoconstriction observed in the animals. This vasoconstriction would prevent the release of heat in the blood to the environment, leading to hyperthermia (13). These findings reveal important mechanisms and pathways of ecstasy-induced hyperthermia that should be targeted for treatment.

Thermogenesis via the UCP3 pathway

Research conducted by Mills et al. (2003) later showed that a different pathway also mediated ecstasy-induced hyperthermia. To investigate the role of uncoupling protein-3 (UCP-3) in ecstasy-induced hyperthermia, Mills et al. (2003) administered ecstasy to UCP-3 deficient mice. The study found that UCP-3 deficient mice showed reduced thermogenesis after ecstasy administration compared to wild type mice (9). In addition, UCP-3 deficient mice showed greater tolerance to ecstasy, and could survive a typically lethal dose (9). In a subsequent review, Mills, Rusyniak, and Sprague (2004) clarify the mechanism of heat production by UCP-3. Previous studies have shown that UCPs are mitochondrial membrane proteins that transport protons (H+ ions) from one side of the membrane to the other, producing energy that would normally be used to convert ADP to ATP (10). With UCP-3, a process known as uncoupling may occur, where this energy is lost as heat (10). It has also been shown that ecstasy can induce release of norepinephrine, which in turn leads to activation of UCP, resulting in thermogenesis (10). However, the precise mechanism in which norepinephrine affects UCP is not currently known (10). Despite this, it is clear that UCP-3 is involved in ecstasy-induced hyperthermia.

Insulin, Glucose, and Free Fatty Acids (FFA) Facilitate Uncoupling through UCP-3

Following prior research conducted on UCP-3, Banks et al. (2009) investigated the role of insulin on ecstasy-induced hyperthermia. Prior research had shown that increased free fatty acid (FFA) levels in the blood amplified hyperthermia following ecstasy administration by increasing uncoupling in UCP-3 (3). Banks et al. (2009) hypothesized that insulin, which is involved in the transport of FFA and glucose into cells, would play a role in ecstasy-induced hyperthermia. In the study, healthy and insulin-resistant rats were given different treatments of saline (control), ecstasy, or ecstasy/ glucose/ insulin (3). Hyperthermia was observed following administration of ecstasy, and rats that were also given insulin and glucose experienced a greater degree of hyperthermia than the other treatment groups (3). In addition, rats that were given ecstasy also exhibited increased insulin levels (3). The findings supported the conclusion that insulin modulates ecstasy-induced hyperthermia through transport of FFA and glucose into the cell that would lead to uncoupling in UCP-3 (3). However, it remains unclear how ecstasy increases insulin levels in the body3 (3).

FAT/CD36 as Transporter of FFA

Much like insulin, the transporter FAT/CD36 is known to be a regulator of FFA levels in the blood (7). In a study conducted on rodent models, Hrometz et al. (2016) investigated the contribution of FAT/CD36 in ecstasy-induced hyperthermia. Exercised and sedentary rats were given either DMSO (a control), SSO (an inhibitor of FAT/CD36), ecstasy, or ecstasy/SSO and monitored for hyperthermia (7). The results revealed that treatment with SSO led to a reduction in hyperthermia in both the sedentary and exercised rats (7). In addition, UCP-3 expression was found to have increased in the exercise group (7). These findings suggested that FAT/CD36 is an important mediator of hyperthermia, and that exercise could exacerbate hyperthermia by increasing levels of UCP-3 in the mitochondria (7). The mechanisms in which exercise increases expression of UCP-3 is still unclear (11).

Strategies to Combat Ecstasy-Induced Hyperthermia

In the following sections, I will briefly highlight potential treatment options that have implications in combating ecstasy-induced hyperthermia. These treatment options fall into two categories: drug options that target the pathways described above, or palliative options that target the symptoms of hyperthermia.

Drug Options

SSO (Sulfo-N-succinimidyl oleate)

As described in the previous section, SSO is an inhibitor of FAT/CD36 that can reduce ecstasy-induced hyperthermia (7). SSO acts an antagonist of FAT/CD36, binding to the transporter to prevent the interaction of FAT/CD36 with FFA (5). When administered to rats, SSO was shown to reduce ecstasy-induced hyperthermia (7). However, SSO is not a currently used drug, and has not been tested on humans.

Clozapine

Clozapine is an antipsychotic drug that has potential to reduce ecstasy-induced hyperthermia in humans (8). Experiments conducted by Kiyatkin et al. (2015) on rats have shown that clozapine can significantly reduce hyperthermia in situations mimicking recreational human use. As described by Kiyatkin et al. (2015), clozapine acts as a inhibitor of vasoconstriction in the body, increasing heat exchange between the body and the environment. The results of the study also showed that rats that were given clozapine following ecstasy administration showed “good health” (8, p. 553) compared to the control group, which was observed to have a 25% death rate (8). It is important to note, however, that these findings only apply to the rats in the study. Clozapine has yet to be tested on humans to treat ecstasy-induced hyperthermia.

Carvedilol

Kiyatkin et al. (2015) showed that carvedilol, an -adrenoceptor and -adrenoceptor antagonist, could also reduce the magnitude of ecstasy-induced hyperthermia in rats following ecstasy administration. These findings are a result of inhibition of the sympathetic nervous system by carvedilol, reducing vasoconstriction in the body (8). Like clozapine, rats given carvedilol showed no signs of illness following ecstasy administration (8). Despite the success of carvedilol to treat ecstasy-induced hyperthermia in rats, carvedilol has yet to be tested on humans to treat hyperthermia.

THC (Δ9-Tetrahydrocannabinol)

THC is a drug that is typically found in cannabis, or marijuana. As described by Taffe (2012), THC has often been taken in conjunction with ecstasy to reduce negative side effects of ecstasy. In a study to investigate the potential for THC to reduce ecstasy-induced hyperthermia in humans, Taffe (2012) administered ecstasy to rhesus monkeys with and without THC. The results of the study showed that THC could reduce significantly reduce hyperthermia in monkeys (14). This is due to the action of THC on the CB1 receptor in the brain, since activating the CB1 receptor has been shown to induce hypothermia (14). Although CB1 receptors are found in the human body, the efficacy of THC to treat ecstasy-induced hyperthermia in humans has yet to be evaluated.

Figure 1. Potential drug options to treat ecstasy-induced hyperthermia, based on literature evaluated in this review.

Palliative Options

Ice packs, cooling blankets, endovascular cooling catheter

Direct cooling of the body is one type of palliative treatment used to combat ecstasy-induced hyperthermia. Ice packs can be “placed in the groin and/or axillae,” (2, p. 255) or cooling blankets can be placed over the body (2). Although these methods of cooling are typical for many hospitals, it can often take hours before body temperatures are lowered to acceptable levels (1). This presents an issue, as increases in duration of hyperthermia is associated with increases in mortality (1). Endovascular cooling catheters can also be used, and have been shown to have success in clinical outcomes (1). However, the case study conducted by Antoine et al. (2018) is the only known use of endovascular cooling catheters to treat ecstasy-induced hyperthermia.

Multiorgan support

Multiorgan support is another type of palliative treatment used to combat complications arising from ecstasy-induced hyperthermia. Although multiorgan support does not address the hyperthermia itself, it can prolong life and increase prognosis for patients who are undergoing cooling (1). In the case study presented by Antoine et al. (2018), “escalating vasopressor and inotropic support” (1) were used to support the patient’s organs after organ failure was detected. Despite the success of multiorgan support, however, multiorgan support merely serves as a bandaid to slow-acting cooling methods that are currently used.

Fasciotomy

Surgical intervention by fasciotomy, where fibers are cut to relieve tension in muscles, have also shown promise in treating ecstasy-induced hyperthermia (1). Ecstasy toxicity has been shown to lead to compartment syndrome, where muscle tension can lead to pressure and constriction of blood vessels (1). A fasciotomy can thus be administered to relieve blood flow in affected areas of the body, allowing for generalized reduction of vasoconstriction and leading to increased heat dissipation to the environment (1). According to Antoine et al. (2018), fasciotomies are not commonly used to treat hyperthermia. The case study presented by Antoine et al. (2018) is one of the few that have shown the procedure’s success.

Cervical sympathectomy

Another surgical intervention that has shown promise is the cervical sympathectomy, which was conducted by Pedersen and Blessing (2001) in their study on rabbits. The procedure was shown to have increased blood flow in the ear of the rabbit and minimize the effects of hyperthermia (13). However, the procedure has not been explored on humans, and its efficacy has only been shown in rabbits (13).

Figure 2. Potential palliative options to treat ecstasy-induced hyperthermia, based on literature evaluated in this review.

Areas for Consideration and Further Research

As shown in the previous section of this literature review, treatment options for ecstasy-induced hyperthermia in humans are limited. Carvedilol, clozapine, SSO, and THC are four potential drug options that have been shown to be effective in rodents (7; 8) and rhesus monkeys (14), but have not been tested in humans. Clinical research is needed to determine the efficacy of these drugs to treat ecstasy-induced hyperthermia in humans.

Pathways of hyperthermia can also serve as potential pharmacological targets for drugs. The 5-HT/ 5-HT2A receptor pathway, for example, has been implicated in ecstasy-induced vasoconstriction (13). Research should be conducted to evaluate drugs that can inhibit the 5-HT/ 5-HT2A receptor pathway. In addition, vasodilating drugs such as nitroglycerin should also be considered for use in reducing ecstasy-induced vasoconstriction.

Thermogenesis is another mechanism of ecstasy-induced hyperthermia that lacks drug options for treatment. Previous studies have shown that uncoupling in UCP-3 induces ecstasy-induced hyperthermia (3; 9; 10). Research should be conducted to evaluate drugs that can reduce insulin levels in the body, or decrease sensitivity to insulin. In addition, research should be conducted to evaluate drugs that can sequester FFA levels in the blood and reduce UCP-3 expression in the mitochondria. These findings may lead to clinical applications in reducing mitochondrial thermogenesis.

Much like the drug options described in this literature review, palliative options for treating ecstasy-induced hyperthermia are also limited (see Figure 2). Surgical therapy and fasciotomies are palliative treatment options that can be used to counteract vasoconstriction in humans. Cervical sympathectomies have also been shown to reduce vasoconstriction in rabbit models, but have not been proven in humans (13). Further research is necessary to determine the efficacy of surgical interventions in attenuating ecstasy-induced hyperthermia.

Other palliative options for treating ecstasy-induced hyperthermia generally involved active cooling procedures, including the use of cooling blankets, ice packs, and endovascular catheters (1; 2). However, many of these procedures have not been shown to be effective (2). Antoine et al. (2018), in their case study, found that the endovascular catheters were more effective than the other cooling procedures. However, this study was the only one of its kind to utilize the endovascular catheter to treat ecstasy-induced hyperthermia (1). Further research should be conducted to evaluate the efficacy of the endovascular catheter in treating ecstasy-induced hyperthermia. In addition, alternative cooling methods should also be investigated, including the use of chilled artificial respirators as a supplement to organ support and industrial fans to increase convection of heat away from the body.

Limitations

This literature review incorporates articles that are greater than 5 years old, with the oldest article published in 2000. However, these articles serve as major findings in the literature for ecstasy-induced hyperthermia, and are continuously cited and self-cited by researchers in the field. Many of these articles were thus included in the article despite age concerns. This literature review may not fully address every possible drug or palliative option for treating ecstasy-induced hyperthermia, but should serve as a suitable starting point to guide further research in the area.

Conclusion

Ecstasy-induced hyperthermia is a growing public health concern that plagues the live music scene. This literature review provides a limited report on our current understanding of the disease in order to guide future research in the area. The findings of this review have revealed two mechanisms of ecstasy-induced hyperthermia: thermogenesis via UCP-3 uncoupling, and vasoconstriction via complex mechanisms. Further research should evaluate the efficacy of potential drug options, including clozapine, carvedilol, THC, SSO, in treating ecstasy-induced hyperthermia in humans. In addition, new drug candidates should be explored that target the pathways of ecstasy-induced hyperthermia described in this review, including the UCP-3/FFA/insulin pathway and the 5-HT/5-HT2A pathway. Furthermore, palliative treatment options for use in clinical settings, including current and new cooling options, need to be disseminated to healthcare practitioners. Chilled artificial respirators and industrial fans are cooling options that may have implications in alleviating hyperthermia in most clinical settings. Surgical therapies such as the fasciotomy and cervical sympathectomy should also be explored for use in alleviating hyperthermia in humans. The findings presented in this review may one day lead to new and effective treatment options for ecstasy-induced hyperthermia. These new treatment options will be crucial in the fight against a growing epidemic in public health and may, with any luck, eventually save lives.

References

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15. Tinsley, G. M., Spillane, M., Grandjean, P. W., Ramirez, A., Willoughby, D. S. (2017). BAIBA Does Not Regulate UCP-3 Expression in Human Skeletal Muscle as a Response to Aerobic Exercise. Journal of the American College of Nutrition,36(3), 200-209. doi:10.1080/07315724.2016.1256240