What Is Tirzepatide?
Tirzepatide is a first-in-class dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist. Unlike semaglutide, which acts only on GLP-1 receptors, tirzepatide activates both the GIP and GLP-1 pathways - two key incretin hormones involved in blood sugar regulation, appetite control, and metabolism. This dual mechanism represents a significant innovation in peptide therapy for metabolic health.
Tirzepatide was originally developed for the treatment of type 2 diabetes and has since been studied for chronic weight management in adults with obesity. It is given as a once-weekly subcutaneous injection. Compounded tirzepatide available through The Pep Club is prepared and dispensed by state-licensed pharmacies, including 503A compounding pharmacies. Compounded medications are not FDA-approved. The FDA does not review compounded drugs for safety, effectiveness or quality before they reach patients. A compounded preparation is not a generic version of, and is not the same as, any FDA-approved medication. It is prescribed only when a licensed provider decides it is appropriate for you.
The development of tirzepatide reflects decades of research into incretin biology. Researchers have studied how GIP and GLP-1 signaling act together. Tirzepatide is a single molecule engineered to engage both receptor systems, making it mechanistically distinct from simply combining two separate drugs.
How Tirzepatide Works
Tirzepatide is designed as a dual agonist at GIP and GLP-1 receptors. In published clinical trials, GLP-1 receptor agonists as a drug class were studied for their action on satiety centers in the brain, on gastric emptying, and on glucose-dependent insulin secretion, and GIP receptor activity was studied for its action on appetite, fat metabolism and the insulin response. Researchers are still studying how much the GIP pathway adds on top of GLP-1 activity. Those trials studied the manufacturers' products, which are FDA-approved. The compounded preparations were not studied in these trials, and results are not guaranteed.
The molecule carries a fatty acid modification that extends its half-life, which is why it is dosed once a week.
What the Published Research Studied
Research note
Tirzepatide has been studied for weight management in the SURMOUNT clinical trial program and for type 2 diabetes in the SURPASS program, large randomized trials published in peer-reviewed journals, including the New England Journal of Medicine. Those trials studied the manufacturers' products, which are FDA-approved. The compounded preparations were not studied in these trials, and results are not guaranteed.
Because of that, this page does not quote trial weight-loss figures as something you can expect, and it does not rank tirzepatide against other medications. Results vary from person to person. Your physician discusses realistic expectations with you at consultation, based on your starting point, medical history and treatment plan.
What Research Has Looked At
Published research on tirzepatide has looked at body weight, HbA1c (a measure of long-term blood sugar control), fasting glucose, triglycerides, blood pressure and insulin sensitivity. Those trials studied the manufacturers' products, which are FDA-approved. The compounded preparations were not studied in these trials, and results are not guaranteed.
For people with obesity-related conditions, weight, blood pressure, cholesterol and blood sugar are connected, which is why your physician reviews your labs and history before deciding on any treatment. For patients who have previously tried a GLP-1-only agonist, tirzepatide's dual mechanism is a different approach your physician may discuss. The once-weekly schedule is set by your physician.
Side Effects and Safety
Safety note
The side effect profile of tirzepatide is similar to other incretin-based therapies, with gastrointestinal effects being the most common. Nausea, diarrhea, constipation, vomiting, and decreased appetite are the most frequently reported side effects. These are generally mild to moderate in severity and tend to decrease over time as the body adjusts. The gradual dose escalation is designed to minimize these effects.
Less common side effects include injection site reactions, hair thinning (often related to rapid weight loss rather than the medication itself), fatigue, and allergic reactions. Serious but rare potential risks include pancreatitis, gallbladder disease, and hypoglycemia (primarily in patients also taking insulin or sulfonylureas for diabetes).
Tirzepatide carries the same boxed warning as semaglutide regarding thyroid C-cell tumors observed in animal studies. It is contraindicated in patients with a personal or family history of medullary thyroid carcinoma or MEN2 syndrome, during pregnancy, and in patients with known hypersensitivity. As with all peptide therapies at The Pep Club, your physician will conduct a thorough medical evaluation before prescribing tirzepatide.
Who Should Consider Tirzepatide?
Tirzepatide may be considered for adults with obesity (BMI of 30 or greater) or adults with overweight (BMI of 27 or greater) who have at least one weight-related comorbidity. It may be particularly appropriate for patients who need substantial weight loss to address health conditions, patients who have not achieved adequate results with GLP-1-only agonists, and patients with concurrent type 2 diabetes who would benefit from both weight loss and improved glycemic control.
Patients considering tirzepatide should understand that it is a long-term treatment for a chronic condition, not a short-term fix. It is meant to be combined with dietary modifications, increased physical activity, and ongoing medical supervision, and results vary. Your physician will discuss whether tirzepatide is the right choice for your specific health profile and goals.
During your consultation, expect a comprehensive review of your medical history, current medications, previous weight loss attempts, and treatment objectives. Your physician will explain the differences between available options - including semaglutide and tirzepatide - so you can make an informed decision about your treatment plan.
Frequently asked
How do I choose between tirzepatide and semaglutide?
The two act on different receptor pathways: semaglutide on GLP-1 receptors, tirzepatide on both GIP and GLP-1 receptors. Published comparisons between them come from clinical trials. Those trials studied the manufacturers' products, which are FDA-approved. The compounded preparations were not studied in these trials, and results are not guaranteed. Which one, if either, is appropriate depends on your medical history, tolerability and treatment goals, and your physician helps decide.
How much weight can I lose with tirzepatide?
Results vary from person to person, and results are not guaranteed. Your clinician discusses realistic expectations with you at consultation, based on your starting point, medical history and treatment plan. Published clinical trials were conducted on FDA-approved products, not on compounded preparations.
How is compounded tirzepatide regulated?
Compounded medications are not FDA-approved. The FDA does not review compounded drugs for safety, effectiveness or quality before they reach patients. A compounded preparation is not a generic version of, and is not the same as, any FDA-approved medication. It is prescribed only when a licensed provider decides it is appropriate for you. Compounded tirzepatide is prepared for an individual prescription by state-licensed pharmacies, including 503A compounding pharmacies, and actual product appearance and labeling may differ from website images.
Can I switch from semaglutide to tirzepatide?
Yes, switching between GLP-1 receptor agonists is possible and sometimes recommended if a patient is not achieving desired results or is experiencing intolerable side effects. A switch is a clinician's decision, typically starting tirzepatide at the initial dose and following the standard escalation protocol.