Tirzepatide

Tirzepatide is a synthetic 39-amino-acid peptide and dual incretin receptor agonist that simultaneously activates both the GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) receptors. Developed by Eli Lilly and approved as Mounjaro (for type 2 diabetes) and Zepbound (for chronic weight management), it has a molecular mass of approximately 4,814 Da and an extended half-life of around five days, supporting once-weekly subcutaneous administration in clinical and research settings.

Tirzepatide exerts its studied effects through simultaneous activation of two key incretin receptor pathways: • GIP receptor agonism — enhances glucose-dependent insulin secretion from pancreatic beta cells in response to meals and is being investigated for effects on fat metabolism and insulin sensitivity. • GLP-1 receptor agonism — delays gastric emptying, signals fullness to the brain's appetite centres and supports glucose-dependent insulin secretion, collectively reducing appetite and food intake. The dual mechanism is researched for its potential to produce greater reductions in body weight and improvements in blood glucose than single-hormone GLP-1 agonists, while maintaining a glucose-dependent insulin response that reduces the risk of hypoglycaemia.

Tirzepatide (LY3437943) is a synthetic peptide engineered from the native GIP sequence, incorporating a C20 fatty acid acylation that enables albumin binding, slows enzymatic degradation and reduces renal clearance — yielding a half-life of approximately five days. Uniquely, it functions as a dual agonist at both the GIP receptor and the GLP-1 receptor, distinguishing it from single GLP-1 agonists such as semaglutide. Its molecular mass is approximately 4,814 Da and its sequence comprises 39 amino acids. GIP receptor agonism is studied for its role in glucose-dependent insulin secretion and its emerging influence on adipose tissue metabolism and bone biology. GLP-1 receptor agonism is associated with delayed gastric emptying, increased satiety signalling, reduced appetite and glucose-dependent insulin secretion. Research suggests the combined engagement of both incretin pathways may produce complementary and potentially superior metabolic effects — including greater reductions in body weight and improvements in glycaemic control — than targeting either receptor alone.

Tirzepatide has been evaluated in the large-scale SURPASS programme (type 2 diabetes) and SURMOUNT programme (obesity and weight management), published in peer-reviewed journals and reviewed by major regulatory authorities including the U.S. FDA and the European Medicines Agency (EMA). Notable clinical findings: • SURMOUNT-1 (N Engl J Med, 2022): In adults with obesity, tirzepatide achieved mean body-weight reductions of up to 22.5% at the highest dose over 72 weeks, significantly exceeding placebo. • SURMOUNT-2 (The Lancet, 2023): In adults with type 2 diabetes and obesity, tirzepatide produced mean weight reductions of up to 15.7%. • SURPASS-2 (N Engl J Med, 2021): In adults with type 2 diabetes, tirzepatide demonstrated superior HbA1c reduction and weight loss compared with semaglutide. Regulatory recognition: • The U.S. FDA approved tirzepatide as Mounjaro for type 2 diabetes in May 2022 and as Zepbound for chronic weight management in November 2023. • The European Medicines Agency (EMA) granted marketing authorisation for Mounjaro in September 2022. These findings are based on peer-reviewed clinical research and regulatory evaluations. Individual results may vary, and this information is provided for research and educational purposes only.