Prescription weight loss medications
Phentermine (Adipex-P®) and phentermine
The Centers for Disease Control and Prevention (CDC) defines overweight as “weight that is higher than what is considered healthy for a given height.” Obesity is a chronic disease state that is further distinguished from the overweight category via the body-mass index (BMI), which is a person’s weight-to-height ratio. Specifically, a BMI of ≥ 25 is considered overweight, while a BMI of ≥ 30 is considered obese. Because obesity increases your risk of metabolic disease states such as hypertension, hyperlipidemia, and type 2 diabetes mellitus as well as mental health conditions such as depression, treating it is pertinent to optimizing one’s health and well-being. Aside from bariatric surgery, patients can treat obesity with increased exercise, improved diet, and utilizing help from FDA-approved medications. Adipex-P® and Ozempic® are two of the most common medications indicated for weight loss.
Phentermine is a stimulant medication that suppresses appetite similarly to amphetamines by increasing noradrenergic (adrenaline) activity. Because it is similar to other central nervous system stimulants, it is a controlled substance in the CIV category. It is most commonly prescribed as a once-daily tablet to be taken in the morning and is indicated for short-term use only (< 12 weeks) and as an adjunct to a healthier diet and increased exercise.
The most common side effects of phentermine are high blood pressure, increased heart rate, heart palpitations, ischemia (lack of oxygen to the heart due to blockage), change in bowel habits, dry mouth, euphoria, dysphoria, restlessness, insomnia, and tremor.
Because of its stimulant properties, phentermine should not be taken by patients with heart disease, high blood pressure, pulmonary hypertension, or a history of addiction or substance abuse.
Topiramate is formulated with phentermine in a combination medication known as Qsymia ®. Topiramate reduces appetite by several unique mechanisms different than phentermine. When combined with phentermine, the indication extends from short-term use (< 12 weeks) to use as a chronic weight management medication. Adipex-P® is also a once-daily medication. The most common side effects of topiramate include headache, paresthesia (skin tingling), dizziness, nausea, change in bowel habits, and taste changes (particularly to carbonated beverages). Topiramate or Qsymia® should not be prescribed (in addition to previously mentioned conditions) to patients with a history of kidney stones, hyperthyroidism, glaucoma, or pregnancy.
Semaglutide (Ozempic®)
Ozempic® is a once-weekly subcutaneous injection that works as a glucagon-like peptide-1 (GLP-1) receptor agonist. It mimics natural body hormones that increase insulin activity and decreases gastric emptying (keeps food in your stomach longer, therefore decreasing appetite). Because it is not a stimulant, it does not have cardiovascular effects (if any, low blood pressure may occur) and the most notable side effects include nausea, vomiting, diarrhea, constipation, fatigue, and headache. There are fewer contraindications for Ozempic® as compared to phentermine – only in patients with a person or family history of certain types of cancer – and it is also not a controlled substance.
Which has better effectiveness?
Always be sure to speak with your doctor and provide a thorough personal and family history before discussing weight-loss medications. There are contraindications and side effects for both phentermine and Ozempic® that would preclude its use in some patients. Similarly, certain histories may promote the use of one medication over another. For example, if you have a history of type 2 diabetes mellitus, then Ozempic® may be a better choice. Someone with no cardiovascular or addiction history who has low energy and motivation may benefit from both appetite and stimulant effects of phentermine.
In a 2022 study pooling data from nearly fifty thousand patients, researchers found that both phentermine-topiramate and Ozempic® decreased body weight by a greater amount than diet and exercise alone – nearly 6-11% of body weight was shed. It was initially noted that phentermine-topiramate had the best effectiveness compared to other weight loss medications. However, Ozempic® was not studied specifically for weight loss when the study was originally completed. Later analysis showed that Ozempic® had a greater weight loss effect compared to phentermine-topiramate and with fewer side effects reported by patients.
