How Do Amphetamines Affect Body Temperature?
Understanding Amphetamines
Amphetamines are a class of potent drugs that have significant effects on the body's central nervous system. They function by increasing the amounts of certain neurotransmitters in the brain, which in turn increase heart rate, blood pressure, and body temperature. This initial section aims to create a deeper understanding of these substances, including their mechanism of action and the various types of amphetamines available.
Mechanism of Action
Amphetamine is a central nervous system stimulant that increases the amounts of dopamine, norepinephrine, and serotonin in the synaptic cleft through a variety of mechanisms. It enters the presynaptic axon terminal through diffusion or uptake by the monoamine transporters DAT, NET, and SERT, and inhibits the metabolism of monoamine neurotransmitters by inhibiting monoamine oxidase (MAO).
In addition, amphetamine stimulates the intracellular receptor TAAR1, which induces internalization or transporter reversal of DAT. This results in an increased efflux of dopamine into the synaptic cleft and reuptake inhibition in the synaptic cleft through DAT internalization and direct competition. The effects of TAAR1 on DAT may also extend to NET and SERT.
Types of Amphetamines
Amphetamine medications predominantly or exclusively contain the d-isomer of amphetamine, which is more potent and clinically effective than the l-isomer. The proper use of these medications for ADHD and narcolepsy treatment is based on factors such as cost, patient preference, and concern for abuse. They are available in various forms, including immediate-release tablets, extended-release capsules, oral solutions, capsules, and chewable tablets. Dosages usually range from 5 mg to 40 mg daily and should not exceed 60 mg, which is the maximum dose for certain adults.
Lisdexamfetamine, a long-acting amphetamine medication, is FDA-approved for the treatment of binge-eating disorder. It is important to note that the use of these substances can lead to side effects such as insomnia, headache, dry mouth, tachycardia, increased systolic blood pressure, restlessness, irritability, and a reduced appetite associated with stunted growth in children who consistently take the medication. In some patients, serious cardiovascular events such as myocardial infarction and sudden cardiac death have been reported. However, several follow-up studies have failed to demonstrate an increased risk of severe cardiovascular events in patients treated with these stimulant medications.
Amphetamine is contraindicated in patients with a range of health conditions, including hypersensitivity to any component of the drug formulation, symptomatic cardiovascular disease, advanced arteriosclerosis, glaucoma, hyperthyroidism, severe hypertension, agitated states, and a history of drug misuse. Furthermore, close monitoring for signs and symptoms of serotonin syndrome is required when amphetamine is used in combination with other serotonergic agents and/or CYP2D6 inhibitors [1].
In conclusion, it is essential to have a comprehensive understanding of amphetamines, including how they work and the various types available, to fully grasp how they affect the body's temperature and other physiological functions.
Effects on Body Temperature
The influence of amphetamines on body temperature is a key area of interest in understanding the overall effects of these substances. The changes in core temperature and the risks associated with hyperthermia are significant aspects to consider when discussing how amphetamines affect body temperature.
Impact on Core Temperature
Amphetamines can cause an elevation in body temperature by impacting the hypothalamus, a region of the brain involved in maintaining homeostasis. This can lead to an increase in body temperature, contributing to a range of physiological responses.
Interestingly, amphetamines have been found to enhance endurance in rats by increasing heat dissipation. This mechanism leads to a slower rise in core body temperature during exercise, enabling the rats to run longer before reaching exhaustion [3]. Similarly, in humans, amphetamine use can improve physical performance by increasing heat dissipation, which delays the rise of core body temperature during physical activity. This allows for improved endurance and extended periods of physical activity.
Hyperthermia Risks
While the impact on core temperature can potentially enhance physical performance, it's crucial to understand the risks associated with elevated body temperatures, particularly hyperthermia. Hyperthermia induced by amphetamines can have detrimental effects on the body, particularly on the brain.
Exposure to amphetamines can disrupt protein function, ion channels, and enhance the production of reactive oxygen species (ROS). This disruption of normal cellular processes can lead to neurotoxicity and damage to brain cells. The risk of hyperthermia underscores the importance of understanding the broad implications of amphetamine use on body temperature.
In conclusion, while amphetamines can potentially delay the rise in core body temperature during physical activity, enhancing endurance, they also carry significant risks due to the potential for hyperthermia. Further research is needed to fully understand these effects and develop strategies to mitigate the associated risks.
Cardiovascular Effects
One of the significant impacts of amphetamines is on the cardiovascular system. These effects can be observed in changes in blood pressure and heart rate, as well as a variety of neurological effects.
Blood Pressure and Heart Rate
Amphetamine use has been associated with an increase in both blood pressure and heart rate. According to a study cited on PubMed, amphetamine use in ischemic stroke patients resulted in a significant increase in peripheral and central systolic blood pressure by 11.2 mm Hg and 9.5 mm Hg respectively, and heart rate by 7 beats per minute. It is important to note that these changes occurred without alterations in cerebral hemodynamics.
The abuse of stimulants like amphetamines is likely to have a stressful effect on the cardiovascular system over time, due to its impact on heart rate, blood vessels, and blood pressure. Medical News Today also reports that research indicates that amphetamine users have 'older' hearts compared to smokers and methadone users, implying a quicker rate of aging in the cardiovascular system.
Neurological Effects
Apart from cardiovascular changes, amphetamines also lead to a number of neurological effects. An overdose of amphetamines can lead to severe intoxication and a range of complications such as respiratory depression, seizures, metabolic acidosis, renal failure, hepatic injury, and coma. Neurological effects such as agitation, aggressive behavior, irritability, headache, and hallucinations have also been documented.
These impacts are not limited to illicit use of amphetamines. Even medical use of amphetamines, such as lisdexamfetamine for treating ADHD, can cause these effects. However, lisdexamfetamine has a longer duration of action, lasting up to 13 hours, due to its slow metabolism.
The cardiovascular and neurological effects of amphetamines underscore the need for caution and medical supervision in their use. Understanding these effects is integral to answering the question of 'how do amphetamines affect body temperature?' as these changes in the body's functioning can lead to an increase in core body temperature and a heightened risk of hyperthermia.
Physical Performance Enhancement
While the potential risks and side effects of amphetamines are well-known, it is also important to explore the reasons behind their use. In particular, many individuals take amphetamines for their performance-enhancing effects. This section will delve into how amphetamines can boost endurance and improve physical activity, despite the potential for increased body temperature.
Endurance and Heat Dissipation
Amphetamines have been found to enhance endurance in rats by increasing heat dissipation. This process leads to a slower rise in core body temperature during exercise, enabling the rats to run for longer periods before reaching exhaustion. Similarly, in humans, amphetamine use can improve endurance by increasing heat dissipation, which delays the rise of core body temperature during physical activity.
However, it's important to note that this effect can also be risky. While it may allow for extended periods of activity, the delayed rise in body temperature can also potentially lead to hyperthermia, a dangerous condition where the body overheats.
Improved Physical Activity
Beyond endurance, amphetamines can also influence general physical performance. Amphetamines work by causing the brain to release dopamine, a neurotransmitter associated with feelings of pleasure and reward. This increase in dopamine can make physical activity more enjoyable, potentially motivating individuals to engage in more extended or intense exercise sessions.
Additionally, certain types of amphetamines, such as lisdexamfetamine, are used for treating conditions like ADHD due to their ability to enhance neurotransmission in the central nervous system. This effect, along with the drug's long-lasting action, can aid in focus and concentration, potentially improving performance in activities requiring sustained attention.
Despite these potential benefits, the use of amphetamines for physical performance enhancement is not without risk. Increased body temperature, cardiovascular effects, and potential for neurological damage are serious considerations. Therefore, any use of amphetamines should be under the guidance of a healthcare professional to ensure safety.
Neurotoxicity and Damage
The physiological impacts of amphetamines extend beyond the immediate effects on body temperature. Long-term use or exposure to these substances, particularly in high doses, can lead to serious neurotoxicity and damage in the brain.
Brain Cell Damage
One of the primary ways amphetamines can affect the brain is through the disruption of normal cellular processes. Amphetamines, particularly when they cause hyperthermia, can disrupt protein function and ion channels, as well as enhance the production of reactive oxygen species (ROS). This disruption can lead to neurotoxicity and damage to brain cells.
Furthermore, hyperthermia likely enhances amphetamine and methamphetamine neurotoxicity directly through these disruptions. This damage can be exacerbated by repetitive seizures, which greatly enhance neurodegeneration in the hippocampus, thalamus, and amygdala under conditions of breakdown of the blood-brain barrier (BBB).
Vascular and Neurological Risk
Beyond the potential for direct brain cell damage, amphetamines also carry a risk of vascular damage, particularly when they induce hyperthermia. Indeed, forebrain neurotoxicity can be indirectly influenced through the effects of amphetamine and methamphetamine-induced hyperthermia on vasculature.
Further, liver damage and elevated cytokines in blood can result when amphetamines produce hyperthermia. These effects could potentially enhance vascular damage and neurotoxicity.
In conclusion, while the immediate effects of amphetamines on body temperature may be the most noticeable, the potential for long-term, irreversible damage to the brain and vascular system is a serious consequence that warrants attention and further study. These findings also underscore the importance of seeking help for amphetamine abuse and addiction, as the risks and potential damage extend far beyond temporary changes in body temperature.
Considerations and Contraindications
Understanding and considering the health risks associated with amphetamines, as well as their contraindications, is crucial for ensuring safety. This section will delve into these aspects, offering insight into how amphetamines affect body temperature and overall health, and who should refrain from their use.
Health Risks
Amphetamines, though they can offer medical benefits when used correctly, also pose significant health risks. Chief among them is the potential for amphetamine abuse to accelerate the degeneration of physiological systems. This may occur due to interference with stem cell functioning and normal cell division, leading to impeded tissue repair and increased tissue injury [7].
Additionally, abuse of stimulants like amphetamines is likely to exert a stressful effect on the cardiovascular system over time. This is due to the impact on heart rate, blood vessels, and blood pressure, which can lead to long-term cardiovascular complications [7].
In fact, research indicates that amphetamine users have 'older' hearts compared to smokers and methadone users. This implies a quicker rate of aging in the cardiovascular system, which can lead to a higher risk of heart-related health issues [7]. However, it's important to note that due to the observational nature of this study, no firm conclusion can be drawn regarding a cause-and-effect relationship between amphetamine abuse and accelerated heart aging.
Contraindications and Monitoring
Certain individuals should refrain from using amphetamines due to pre-existing health conditions. Amphetamines are contraindicated in patients with hypersensitivity to any component of the drug formulation, during or within 14 days of MAOI therapy, and in patients with symptomatic cardiovascular disease, advanced arteriosclerosis, glaucoma, hyperthyroidism, severe hypertension, agitated states, and a history of drug misuse.
For individuals who are using amphetamines, close monitoring for signs and symptoms of serotonin syndrome is required, especially when amphetamines are used in conjunction with other serotonergic agents and/or CYP2D6 inhibitors.
Adverse effects of amphetamine use may be managed with benzodiazepines, antipsychotics, beta-blockers, and intravenous nitrates, depending on the specific symptoms and severity of intoxication.
In conclusion, while amphetamines can offer certain medical benefits, they also pose significant health risks and require careful monitoring. Individuals with pre-existing health conditions or a history of drug misuse should avoid using amphetamines, and those who do use these substances should do so under close medical supervision.
References
[1]: https://www.ncbi.nlm.nih.gov/books/NBK556103/
[2]: https://www.northstarbehavioralhealthmn.com/resources/how-do-amphetamines-affect-body-temperature
[3]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5027360/
[4]: https://go.drugbank.com/drugs/DB00182
[5]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3666194/