Quick Takes: What You Need to Know About The 5 FDA-Approved Obesity Drugs

Scott Kahan, MD, MPH


March 02, 2017

A recent study found that patients went to the pharmacy 15 times more frequently for antidiabetic drugs than for antiobesity medications even though 116 million adults fit the criteria for use of these drugs, compared with less than 30 million for whom antidiabetes drugs are indicated.

Why? Why are we so reluctant to prescribe these drugs? Experts cite a number of reasons. One is a belief that obesity does not require pharmacotherapy, although the experience of virtually every clinician would argue that many, if not most, patients cannot achieve meaningful weight loss with behavioral changes alone. Others point to concerns about insurance coverage for these agents, which may not be approved by an individual patient's insurance plan and can cost about $200 per month—a price that many frustrated patients may well be willing to pay. Perhaps most important, primary care clinicians are just not familiar with these agents, nor comfortable with prescribing them.

Available agents are able to help patients achieve, on average, 5%-15% weight loss, which usually leads to significant improvements in many comorbid conditions, including hyperglycemia and diabetes, hyperlipidemia, hypertension, and others.

What do you need to know? The US Food and Drug Administration (FDA) has approved five medicines for long term use, including four relatively new drugs—the first drugs approved for obesity in 13 years—with solid data on long-term efficacy and safety. The indications for all are either a body mass index (BMI) > 30 kg/m² or a BMI > 27 kg/m² with comorbidity.

Here, we provide a brief primer describing the five medications that are approved for long-term use for obesity management. To view the table, click here. For a downloadable table that can be printed and shared, click here.

Orlistat (Rx: Xenical®; OTC: alli®)

Type of drug/actions: Peripherally acting pancreatic lipase inhibitor; reduces absorption of ingested fat.

Effects: Orlistat plus behavioral counseling doubled weight loss seen with placebo/counseling. Progression to diabetes reduced.

Dosing: 120 mg three times daily with meals (or over-the-counter alli® at half dose, 60 mg)

Adverse effects: Gastrointestinal (diarrhea, flatulence), especially if large amounts fat are ingested.

Precautions: Binds fat-soluble vitamins. Patient should take a multivitamin at bedtime. Follow a reduced-fat, reduced-calorie diet.

Contraindications: Pregnancy, cholestasis, chronic malabsorption syndromes, coadministration with cyclosporine. Can increase urinary oxalate and predispose to kidney stones.

Phentermine/Topiramate ER (Qsymia®)

Type of drug/actions: Combination of appetite-suppressant sympathomimetic amine and anticonvulsant.

Effects: Additive effect of drug combination leads to more weight loss than either agent alone; reduced progression to type 2 diabetes.

Dosing: 3.75 mg phentermine/23 mg topiramate ER; escalate to 7.5/46 mg after 2 weeks. Response should be evaluated after 12 weeks, and treatment should either be escalated to a higher dose or discontinued if patients do not achieve ≥ 3% weight loss.

Adverse effects: Paresthesia, dizziness, dysgeusia, insomnia, constipation, dry mouth.

Precautions: Pregnancy, glaucoma, use of monoamine oxidase inhibitors (MAOIs), hyperthyroidism.

Contraindications: Topiramate is a known teratogen; pregnancy should be ruled out before starting the medication, and women of childbearing age should use contraception and have monthly pregnancy testing during use.


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