Phentermine is a prescription medication used for weight management. Its active ingredient is phentermine hydrochloride. It helps individuals lose weight when diet and exercise are insufficient.
The Core Chemical
Phentermine, as a chemical compound, is classified as a sympathomimetic amine. Its structure bears a similarity to amphetamines, though it is considered an atypical amphetamine.
Mechanism of Action
Phentermine hydrochloride primarily exerts its effects by influencing certain neurotransmitters within the brain. It acts as a norepinephrine and dopamine releasing agent, increasing the levels of these chemical messengers in the central nervous system. This increase in neurotransmitter activity stimulates the sympathetic nervous system, mimicking a “fight-or-flight” response.
This physiological response helps to suppress appetite and promote feelings of fullness. Phentermine is thought to reduce hunger signals and may also contribute to increased energy expenditure and the breakdown of stored fat for energy. Some reports also suggest it can inhibit neuropeptide Y, which is involved in hunger induction, and may indirectly affect serotonin levels.
Therapeutic Use
Phentermine is prescribed for short-term weight loss as an adjunct to a regimen that includes exercise, behavioral changes, and caloric restriction. It is usually recommended for individuals with a Body Mass Index (BMI) of 30 kg/m² or greater. The medication may also be considered for those with a BMI of 27 kg/m² or greater who have other weight-related risk factors, such as controlled hypertension, diabetes, or high cholesterol.
Key Safety Information
Taking phentermine can lead to common side effects, including dry mouth, insomnia, headache, and restlessness. It can also cause increased heart rate, elevated blood pressure, and gastrointestinal issues like constipation or diarrhea.
Phentermine is not suitable for everyone and has specific contraindications. It should not be used by individuals with a history of cardiovascular disease, including coronary artery disease, stroke, or uncontrolled high blood pressure. Other contraindications include hyperthyroidism, glaucoma, agitated states, a history of drug abuse, and pregnancy or breastfeeding.
Due to its potential for abuse and dependence, phentermine is classified as a Schedule IV controlled substance by the Drug Enforcement Administration (DEA). This classification means it has an accepted medical use but carries a risk of misuse. A prescription is required for this medication, and it is generally not intended for long-term use.