Medical weight loss
Tirzepatide: What It Treats and How It Works
Tirzepatide is the medicine in Zepbound and Mounjaro. It acts on two hormone receptors, GIP and GLP-1, to affect appetite and glucose regulation. Both brands are weekly injections, but their approved uses and treatment targets differ.
The prescription brand identifies the approved use
| Brand | What it is approved to treat |
|---|---|
| Zepbound | Long-term weight reduction and maintenance in eligible adults; moderate to severe obstructive sleep apnea in adults with obesity. |
| Mounjaro | Type 2 diabetes in adults and children aged 10 or older; cardiovascular risk reduction in adults with type 2 diabetes at high risk for major cardiovascular events. |
Zepbound weight treatment is combined with a reduced-calorie diet and increased activity. Adult candidates generally have obesity, or overweight with a weight-related condition. Mounjaro's diabetes and cardiovascular indications have different eligibility requirements. An insurer can also apply separate coverage rules to the two brands.
The sleep-apnea indication requires diagnosed moderate to severe obstructive sleep apnea and obesity. A sleep clinician should review treatment response and any changes to positive airway pressure or other care. Improved weight does not establish that sleep apnea has resolved.
Two receptor pathways contribute to the effects
GIP and GLP-1 are involved in the body's response to food. Tirzepatide increases insulin release when glucose is high, reduces glucagon release, influences appetite, and delays stomach emptying. These effects can lower glucose and reduce food intake. The degree of weight or glucose change varies across people.
Treatment begins at a low dose and increases gradually to reduce gastrointestinal effects. For Zepbound, 2.5 mg weekly is the starting dose for four weeks, followed by 5 mg. Later increases depend on response and tolerability. The maintenance dose differs between weight and sleep-apnea treatment.
Review safety and other medicines before starting
Tirzepatide is contraindicated with personal or family medullary thyroid carcinoma, MEN2, or serious hypersensitivity to the product. The thyroid warning is based on findings in rats; its relevance to humans is unknown. Discuss previous pancreatitis, gallbladder disease, severe gastroparesis, kidney problems, and diabetic eye disease.
Insulin or sulfonylurea treatment can raise hypoglycemia risk and may need adjustment. Tirzepatide's delayed stomach emptying can also affect oral medicines. The US labels advise switching from oral hormonal contraception to a nonoral method, or adding a barrier method, for four weeks after starting and four weeks after each dose increase.
Discuss pregnancy plans and breastfeeding. Weight loss offers no benefit during pregnancy, and Zepbound should be discontinued when pregnancy is recognized. Tell the anesthesia team about treatment before surgery or deep sedation so it can give individualized instructions.
Match training and follow-up to the supplied product
Current presentations include different pens and vials. Some contain one dose and others contain four. The instructions and liquid volumes vary, so training should cover the actual presentation received. Get new instructions if the device or concentration changes. Do not calculate a dose using another person's syringe chart.
Nausea, diarrhea, constipation, vomiting, and abdominal discomfort are common. Report symptoms that interfere with eating or drinking before increasing the dose. Severe persistent abdominal pain, dehydration, or allergic symptoms require prompt medical attention.
Arrange ongoing review of the treated condition, nutrition, adverse effects, and access to medication. Compounded tirzepatide is not FDA-approved; FDA warns about incorrect dosing, fraudulent labeling, and inadequate refrigeration. Verify the pharmacy and exact product behind any offer.
Sources
References cited in this article.