It is common to encounter confusion surrounding phentermine and a historical weight-loss combination known as “Phen-Fen.” While both names contain “phen,” they refer to distinct entities with different historical uses and associated health considerations. Understanding the nuances between them is important for clarity regarding past and present weight management approaches.
Understanding “Phen-Fen”
“Phen-Fen” was a widely used prescription weight-loss treatment in the 1990s. It was a combination of two separate medications: fenfluramine (marketed as Pondimin) and phentermine. A related combination, Dexfen-Phen, used dexfenfluramine (marketed as Redux) instead of fenfluramine. Both fenfluramine and dexfenfluramine functioned as appetite suppressants.
The rationale behind combining these drugs was to achieve greater appetite suppression with potentially fewer side effects than either drug alone. Despite never receiving formal FDA approval as a combined product, this therapy was broadly prescribed. The FDA requested the withdrawal of fenfluramine and dexfenfluramine from the market in September 1997 due to safety concerns.
The Risks of “Phen-Fen”
The “Phen-Fen” combination became associated with severe health risks. A primary concern was primary pulmonary hypertension (PPH), a serious and potentially fatal lung disease characterized by high blood pressure in the arteries of the lungs. This condition can lead to shortness of breath, reduced energy, and other troubling symptoms.
Another significant risk was valvular heart disease, specifically affecting the heart valves, such as the aortic and mitral valves. Studies indicated that approximately 30% of patients evaluated after taking these drugs had abnormal echocardiograms, even without symptoms. The heart valves could develop an unusual morphology, including glistening white plaque-like encasement of leaflets, impairing their proper function and leading to regurgitation.
The Distinction Between Phentermine and “Phen-Fen”
Phentermine is not the same as “Phen-Fen.” The dangerous components responsible for the severe heart and lung problems were fenfluramine and dexfenfluramine.
Phentermine, when prescribed alone, has a different safety profile and remains an FDA-approved medication. Unlike the banned combination, phentermine itself was not withdrawn from the market by the FDA in 1997.
Phentermine’s Current Use and Considerations
Phentermine is an FDA-approved prescription medication for short-term weight loss. It is generally used as an adjunct to a regimen of caloric restriction, exercise, and behavioral modification in individuals with exogenous obesity. Its mechanism of action involves stimulating the central nervous system, primarily by increasing the release of norepinephrine in the hypothalamus, which suppresses appetite and may increase resting energy expenditure.
The medication is typically prescribed for a period of a few weeks, generally up to 12 weeks, as its appetite-suppressing effects may diminish over time. Common side effects can include dry mouth, insomnia, constipation, dizziness, and headache. Cardiovascular effects like palpitations, increased heart rate, and elevated blood pressure have also been reported.
Phentermine is contraindicated for individuals with a history of cardiovascular disease, uncontrolled high blood pressure, hyperthyroidism, glaucoma, or a history of drug abuse. It is classified as a Schedule IV controlled substance due to its stimulant properties and potential for abuse or dependence, although the risk of addiction is considered low when used as prescribed. Medical supervision is necessary to monitor for side effects and ensure appropriate use.