phentermine
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What is phentermine?
Phentermine is a sympathomimetic amine drug used as a short-term treatment for obesity. It stimulates the sympathetic nervous system by prompting the release of catecholamines, like dopamine, epinephrine, and norepinephrine, which reduces hunger sensations and promotes fat use.
Common side effects include dizziness, headache, and insomnia. Phentermine is typically used as a monotherapy because it has a high likelihood of drug interactions, which can have severe and potentially fatal reactions. For example, combining phentermine with monoamine oxidase inhibitors (MAOIs) can induce a hypertensive crisis.
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What is phentermine used for?
Phentermine is a drug used short-term alongside exercise and a healthy diet to treat obesity. It works by stimulating the sympathetic nervous system through the release of catecholamines, which reduces hunger sensations and promotes fat use for energy, leading to weight loss.
Common side effects include dizziness, headache, and insomnia. Phentermine has a high likelihood of drug interactions, some of which can be dangerous. The combination of fenfluramine and phentermine (fen-phen) was withdrawn from the market in 1997 due to potentially fatal cardiovascular risks.
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How does phentermine help with weight loss?
Phentermine is a drug used alongside diet and exercise for short-term obesity treatment. It stimulates the sympathetic nervous system by releasing catecholamines like norepinephrine, dopamine, and epinephrine.
Norepinephrine triggers the fight-or-flight response, reducing appetite and increasing fat breakdown, which promotes weight loss. Weight loss varies, but many individuals lose about 3% of their body weight within three months.
Common side effects include dizziness, headache, and gastrointestinal issues. Phentermine is typically used alone due to its high risk of drug interactions.
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What are common side effects of phentermine?
Common side effects of phentermine are largely linked to its stimulatory effects on the nervous system. They can include dizziness, headache, high blood pressure, insomnia, irregular heart rate, restlessness, and tremor. Gastrointestinal issues like constipation, diarrhea, and vomiting are also common. Some people may also have changes in libido or impotence.
Phentermine has a high likelihood of drug-drug interactions. Combining fenfluramine-phentermine (fen-phen) can cause potentially fatal cardiovascular disease. Because of this risk, the combination was withdrawn from the market in 1997.
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Who should not take phentermine?
Phentermine's side effects, such as dizziness, headache, and high blood pressure, mainly arise from its stimulation of the nervous system. It also commonly causes gastrointestinal issues like constipation, diarrhea, and vomiting. Some patients may also experience changes in libido or impotence.
Due to its high likelihood of drug-drug interactions, phentermine is usually taken as a monotherapy. Combining phentermine with monoamine oxidase inhibitors (MAOIs) can induce a hypertensive crisis. The combination of fenfluramine-phentermine (fen-phen) can cause potentially fatal cardiovascular disease.
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How is phentermine different from other weight loss drugs?
Phentermine is a drug used to treat obesity. It is the oldest and most commonly prescribed weight loss drug, and has been available since 1959.
Phentermine is a sympathomimetic amine, which means it stimulates the sympathetic nervous system by releasing catecholamines, such as dopamine, epinephrine, and norepinephrine. This process helps to suppress appetite and increase the breakdown of stored fat for energy, which leads to weight loss.
Phentermine differs from other weight loss drugs, such as Belviq and Wegovy, in its mechanism of action and composition. Belviq decreases cravings for carbohydrates by stimulating the release of serotonin. Qsymia combines phentermine and topiramate to leverage the weight-loss side effects of topiramate, an antiepileptic drug, and the stimulant properties of phentermine.
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phentermine, drug used in the treatment of obesity. Phentermine is the most commonly prescribed drug for weight loss, and it is the oldest such drug still in use, having been first made available by prescription in 1959. Phentermine is available in capsule or tablet form and is used only as a short-term treatment, in conjunction with a healthy eating plan and exercise, to help patients lose weight. It is known by several trade names, among them Adipex-P, Duromine, Lomaira, and Suprenza. An anti-obesity treatment marketed as Qsymia consists of a combination of phentermine and topiramate, a drug used in the treatment of epilepsy and migraine.
Mechanism of action
Phentermine is classified as a sympathomimetic amine. It activates the sympathetic nervous system in a manner similar to naturally occurring catecholamine substances in the body, and, similar to those substances, its chemical structure contains an amine (a nitrogen-containing compound), the presence of which influences drug activity. Catecholamines include the neurotransmitters dopamine, epinephrine, and norepinephrine. Although the precise mechanism of action of phentermine remains unclear, the drug appears to stimulate the sympathetic nervous system by prompting the release of catecholamines to varying degrees. The drug also appears to prevent the reuptake of catecholamines by neurons, thereby extending their activity, and may affect the release and reuptake of the neurotransmitter serotonin.
The most notable actions associated with phentermine involve norepinephrine. Norepinephrine activates the fight-or-flight response, which is marked by changes in activity in the nervous system and the endocrine system that prepare an individual to react or retreat in response to a threat. Among the effects of these changes are suppression of appetite and increased breakdown of stored fat for energy. Via these processes, phentermine helps reduce sensations of hunger and promotes fat use, leading to weight loss. The amount of weight that is lost varies by individual, and most weight loss occurs within the first weeks of treatment, with many patients losing about 3 percent of body weight by the end of three months.
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Side effects and drug interactions
Side effects of phentermine are largely associated with its stimulatory actions on the nervous system and may include dizziness, headache, high blood pressure, insomnia, irregular heart rate, restlessness, and tremor. Gastrointestinal disturbances are common; examples include constipation, diarrhea, and vomiting. Some patients also experience changes in libido or impotence.
Phentermine is usually taken as a monotherapy (single-drug therapy), owing to its high likelihood for drug-drug interactions, wherein phentermine reduces the effectiveness of certain drugs, other drugs reduce the effectiveness of phentermine, or the drugs interact in ways that significantly increase the risk for severe and potentially fatal reactions. Notable interactions include those that can occur between phentermine and monoamine oxidase inhibitors (MAOIs) to induce a hypertensive crisis, in which blood pressure escalates to dangerously high levels. The combination of fenfluramine-phentermine (fen-phen), an anti-obesity treatment that was popular in the 1990s, causes potentially fatal cardiovascular disease; owing to this risk, the combination was withdrawn from the market in 1997.