Obesity: When to consider medication
These 4 cases illustrate how weight loss drugs—including the 4 newest—can be integrated into a treatment plan that includes diet, exercise, and behavior modification
Ask 2 important questions
When considering an antiobesity agent for any patient, there are 2 important questions to ask:
- Are there contraindications, drug-drug interactions, or undesirable adverse effects associated with this medication that could be problematic for the patient?
- Can this medication improve other symptoms or conditions the patient has?
In addition, see “Before prescribing antiobesity medication . . .” below.
Have a frank discussion with the patient and be sure to cover the following points:
,The rationale for pharmacologic treatment is to counteract adaptive physiologic responses, which increase appetite and reduce energy expenditure, in response to diet-induced weight loss.
Antiobesity medication is only one component of a comprehensive treatment plan, which also includes diet, physical activity, and behavior modification.
Antiobesity agents are intended for long-term use, as obesity is a chronic disease. If/when you stop the medication, there may be some weight regain, similar to an increase in blood pressure after discontinuing an antihypertensive agent.
Because antiobesity medications improve many parameters including glucose/hemoglobin A1c, lipids, blood pressure, and waist circumference, it is possible that the addition of one antiobesity medication can reduce, or even eliminate, the need for several other medications.
Remember that many patients who present for obesity management have experienced weight bias. It is important to not be judgmental, but rather explain why obesity is a chronic disease. If patients understand the physiology of their condition, they will understand that their limited success with weight loss in the past is not just a matter of willpower. Lifestyle change and weight loss are extremely difficult, so it is important to provide encouragement and support for ongoing behavioral modification.
Phentermine/topiramate ER
Phentermine/topiramate ER is a good first choice for this young patient with class I (BMI 30–34.9 kg/m2) obesity and migraines, as she can likely tolerate a stimulant and her migraines might improve with topiramate. Before starting the medication, ask about insomnia and nephrolithiasis in addition to anxiety and other contraindications (ie, glaucoma, hyperthyroidism, recent monoamine oxidase inhibitor use, or a known hypersensitivity or idiosyncrasy to sympathomimetic amines).23 The most common adverse events reported in phase III trials were dry mouth, paresthesia, and constipation.24–26
Not for pregnant women. Women of childbearing age must have a negative pregnancy test before starting phentermine/topiramate ER and every month while taking the medication. The FDA requires a Risk Evaluation and Mitigation Strategy (REMS) to inform prescribers and patients about the increased risk of congenital malformation, specifically orofacial clefts, in infants exposed to topiramate during the first trimester of pregnancy.42 REMS focuses on the importance of pregnancy prevention, the consistent use of birth control, and the need to discontinue phentermine/topiramate ER immediately if pregnancy occurs.
Flexible dosing. Phentermine/topiramate ER is available in 4 dosages: phentermine 3.75 mg/topiramate 23 mg ER; phentermine 7.5 mg/topiramate 46 mg ER; phentermine 11.25 mg/topiramate 69 mg ER; and phentermine 15 mg/topiramate 92 mg ER. Gradual dose escalation minimizes risks and adverse events.23
Monitor patients frequently to evaluate for adverse effects and ensure adherence to diet, exercise, and lifestyle modifications. If weight loss is slower or less robust than expected, check for dietary indiscretion, as medications have limited efficacy without appropriate behavioral changes.
Discontinue phentermine/topiramate ER if the patient does not achieve 5% weight loss after 12 weeks on the maximum dose, as it is unlikely that she will achieve and sustain clinically meaningful weight loss with continued treatment.23 In this case, consider another agent with a different mechanism of action. Any of the other antiobesity medications could be appropriate for this patient.
CASE 2 Overweight woman with comorbidities
A 52-year-old overweight woman (BMI 29 kg/m2)with type 2 diabetes, hyperlipidemia, osteoarthritis, and glaucoma has recently hit a plateau with her weight loss. She lost 45 lb secondary to diet and exercise, but hasn’t been able to lose any more. She also struggles with constant hunger. Her medications include metformin 1,000 mg twice per day, atorvastatin 10 mg/d, and occasional acetaminophen/oxycodone for knee pain until she undergoes a left knee replacement. Laboratory values are normal except for a hemoglobin A1c of 7.2%.
The patient is afraid of needles and cannot tolerate stimulants due to anxiety. Which medication is an appropriate next step for this patient?
