December marks the advent of the approval of tirzepatide (Zepbound) for on-label treatment of obesity. In November 2023, the US Food and Drug Administration (FDA) approved it for the treatment of obesity in adults.
In May 2022, the FDA approved Mounjaro, which is tirzepatide, for type 2 diabetes. Since then, many physicians, including myself, have prescribed it off-label for obesity. As an endocrinologist treating both obesity and diabetes,
The Expertise
Because GLP-1 receptor agonists have been around since 2005, we’ve had over a decade of clinical experience with these medications. Table 2 provides more nuanced information on tirzepatide (as Zepbound, for obesity) based on our experiences with dulaglutide, liraglutide, semaglutide, and tirzepatide (as Mounjaro).
The Reality
In today’s increasingly complex healthcare system, the reality of providing high-quality obesity care is challenging. When discussing tirzepatide with patients, I use a 4 Cs schematic — comorbidities, cautions, costs, choices — to cover the most frequently asked questions.
Comorbidities
In trials, tirzepatide reduced A1c by about 2%. In one diabetes trial, tirzepatide reduced liver fat content significantly more than the comparator (insulin), and trials of tirzepatide in nonalcoholic steatohepatitis are ongoing. A prespecified meta-analysis of tirzepatide and cardiovascular disease estimated a 20% reduction in the risk for cardiovascular death, myocardial infarction, stroke, and hospitalized unstable angina. Tirzepatide as well as other GLP-1 agonists may be beneficial in alcohol use disorder. Prescribing tirzepatide to patients who have or are at risk of developing such comorbidities is an ideal way to target multiple metabolic diseases with one agent.
Cautions
The first principle of medicine is “do no harm.” Tirzepatide may be a poor option for individuals with a history of pancreatitis, gastroparesis, or severe gastroesophageal reflux disease. Because tirzepatide may interfere with the efficacy of estrogen-containing contraceptives during its uptitration phase, women should speak with their doctors about appropriate birth control options (eg, progestin-only, barrier methods). In clinical trials of tirzepatide, male participants were also advised to use reliable contraception. If patients are family-planning, tirzepatide should be discontinued 2 months (for women) and 4 months (for men) before conception, because its effects on fertility or pregnancy are currently unknown.
Costs
At a retail price of $1279 per month, Zepbound is only slightly more affordable than its main competitor, Wegovy (semaglutide 2.4 mg). Complex pharmacy negotiations may reduce this cost, but even with rebates, coupons, and commercial insurance, these costs still place tirzepatide out of reach for many patients. For patients who cannot access tirzepatide, clinicians should discuss more cost-feasible, evidence-based alternatives: for example, phentermine, phentermine-topiramate, naltrexone-bupropion, metformin, bupropion, or topiramate.
Choices
Patient preference drives much of today’s clinical decision-making. Some patients may be switching from semaglutide to tirzepatide, whether by choice or on the basis of physician recommendation. Although no head-to-head obesity trial exists, data from SURPASS-2 and SUSTAIN-FORTE can inform therapeutic equivalence:
- Semaglutide 1.0 mg to tirzepatide 2.5 mg will be a step-down; 5 mg will be a step-up
- Semaglutide 2.0 or 2.4 mg to tirzepatide 5 mg is probably equivalent
The decision to switch therapeutics may depend on weight loss goals, side effect tolerability, or insurance coverage. As with all medications, the use of tirzepatide should progress with shared decision-making, thorough discussions of risks vs benefits, and individualized regimens tailored to each patient’s needs.
The newly approved Zepbound is a valuable addition to our toolbox of obesity treatments. Patients and providers alike are excited for its potential as a highly effective antiobesity medication that can cause a degree of weight loss necessary to reverse comorbidities. The medical management of obesity with agents like tirzepatide holds great promise in addressing today’s obesity epidemic.
Dr. Tchang is Assistant Professor, Clinical Medicine, Division of Endocrinology, Diabetes, and Metabolism, Weill Cornell Medicine; Physician, Department of Medicine, Iris Cantor Women’s Health Center, Comprehensive Weight Control Center, New York, NY. She disclosed ties to Gelesis and Novo Nordisk.
A version of this article appeared on Medscape.com.