▎Tirzepatid Research
What is the research background of Tirzepatid?
Tirzepatid is a synthetic polypeptide drug. Its research and development stem from a deep understanding of the limitations of existing GLP-1 receptor agonists in the treatment of type 2 diabetes and obesity at that time. Although GLP-1 receptor agonists have shown excellent performance in blood glucose control and weight loss, scientists found that their activation of the GIP receptor is relatively weak, which limits the efficacy of the drugs to a certain extent. Therefore, the research and development team was committed to developing a new drug that can activate both the GIPR and GLP-1R simultaneously to achieve more comprehensive and effective blood glucose control and weight management[1].
During the research and development process of Tirzepatid, scientists carried out a large number of basic research and clinical trials. In the preclinical research stage, animal experiments were used to thoroughly evaluate the pharmacodynamic properties of Tirzepatid. The results confirmed its potential in blood glucose control and weight loss, laying the foundation for subsequent clinical trials. Subsequently, Tirzepatid entered the clinical trial stage, including phases I, II, and III. Phase I mainly evaluated the safety, tolerability, and pharmacokinetic properties of the drug, and the results showed good safety and tolerability. Phase II further explored the efficacy and safety of different doses in patients with type 2 diabetes, preliminarily determining the effective dose range. The key phase III clinical trials, such as the SURPASS series of studies, involved a large number of patients with type 2 diabetes. The results showed that Tirzepatid was significantly superior to existing GLP-1 receptor agonists, such as Semaglutid, in reducing blood glucose and weight, providing strong evidence for the marketing application[1].
Tirzepatid is a polypeptide composed of 39 amino acids, and its structure has been modified to improve its stability and pharmacodynamics. Its unique structural design enables it to integrate the effects of two incretins, GIP and GLP-1, into a single molecule, activating the hormone receptors involved in blood glucose control through a dual mechanism. Specifically, on the one hand, it acts on the pancreas to promote insulin secretion and inhibit glucagon release to lower blood glucose; on the other hand, it acts on the central nervous system, delaying gastric emptying, increasing satiety, reducing appetite and food intake, and achieving weight management. This dual mechanism gives Tirzepatid unique advantages in the treatment of type 2 diabetes and obesity, providing patients with a more comprehensive treatment option[1].
What is the mechanism of action of Tirzepatid?
Tirzepatid lowers blood glucose through the following multiple mechanisms:
Activation of GLP-1 Receptors: Tirzepatid binds to the GLP-1 receptors on pancreatic beta cells, mimicking the action of natural GLP-1. GLP-1 is a hormone produced by the intestine that is crucial for maintaining glucose homeostasis. It can promote insulin synthesis, secretion, and glucose sensing, and reduce glucagon secretion to promote satiety and suppress appetite. In patients with type 2 diabetes, insufficient insulin secretion or reduced cellular sensitivity to insulin leads to elevated blood glucose. Tirzepatid increases insulin secretion by activating GLP-1 receptors, improving blood glucose control. At the same time, the activation of GLP-1 receptors can also inhibit the release of glucagon, further reducing the sources of blood glucose and contributing to blood glucose control [2].
Activation of GIP Receptors: Tirzepatid acts on GIP receptors, and its activation can enhance insulin sensitivity and secretion. GIP receptors are mainly present in tissues such as pancreatic beta cells. After activation, through intracellular signal pathway transduction, insulin secretion is increased, and the cell’s responsiveness to insulin is enhanced, reducing blood glucose more effectively[2]. This dual receptor agonist effect makes Tirzepatid more effective than single GLP-1 receptor agonists in promoting insulin secretion and inhibiting glucagon release [2].
Delaying Gastric Emptying and Increasing Satiety: Tirzepatid can delay gastric emptying, prolonging the residence time of food in the stomach, slowing down the absorption rate of nutrients, and preventing a sharp rise in postprandial blood glucose. Its effect on gastric emptying is comparable to that of GLP-1 receptor agonists. At the same time, it acts on the central nervous system, increasing satiety, reducing appetite and food intake, which is especially suitable for the obesity problem often accompanied by patients with type 2 diabetes, helping to improve insulin resistance and the overall metabolic condition[2].
Improving Insulin Sensitivity and Lipid Metabolism: Tirzepatid can increase the level of adiponectin, an adipocytokine related to insulin sensitivity, helping to improve insulin sensitivity, enabling cells to more effectively uptake and utilize glucose, and reducing blood glucose (Anonymous, 2023). In addition, it can also improve the lipid profile, having a potential protective effect on cardiovascular health. It has been proven to be able to improve blood pressure, reduce LDL cholesterol and triglycerides[3].
What are the related studies?
Efficacy on Weight Management in Patients with Obesity and Type 2 Diabetes
Numerous clinical studies have confirmed that Tirzepatid has a significant weight loss effect. In the “SURMOUNT-2” study, this phase 3, double-blind, randomized, placebo-controlled trial was conducted in seven countries. Adults (aged ≥ 18 years) with a BMI of 27 kg/m² or higher and HbA₁c of 7 – 10% were enrolled and randomly assigned to receive once-weekly subcutaneous injection of Tirzepatid (10 mg or 15 mg) or placebo for 72 weeks. The results showed that at week 72, the percentage of weight loss in the Tirzepatid 10 mg and 15 mg groups was -12.8% and -14.7% respectively, compared with -3.2% in the placebo group. The estimated treatment differences of Tirzepatid 10 mg and 15 mg compared with the placebo were -9.6 percentage points and -11.6 percentage points respectively, which were statistically significant (p < 0.0001). In addition, more patients receiving Tirzepatid treatment reached the threshold of a 5% or greater weight loss (79 – 83% vs 32%) (Garvey W T, 2023). In this study, the average baseline weight was 100.7 kg, the BMI was 36.1 kg/m², and the HbA₁c was 8.02%. After 72 weeks of treatment, Tirzepatid not only significantly reduced body weight but also had a positive effect on blood glucose control [4].
Improvement of Diabetic Neuropathy
Studies have pointed out that GLP1-RAs can reduce the risk of dementia in patients with type 2 diabetes by improving memory, learning, and overcoming cognitive impairment. As a dual GIP-RA/GLP-1RA, in the neuroblastoma cell line (SHSY5Y), research has found that Tirzepatid has an impact on markers of neuronal growth (CREB and BDNF), apoptosis (BAX/Bcl2 ratio), differentiation (pAkt, MAP2, GAP43, and AGBL4), and insulin resistance (GLUT1, GLUT4, GLUT3, and SORBS1). The results emphasize the role of Tirzepatid in activating the pAkt/CREB/BDNF pathway and downstream signaling cascades and its neuroprotective efficacy, indicating that it can counteract the effects associated with hyperglycemia and insulin resistance at the neuronal level. Therefore, Tirzepatid can improve the neurodegeneration caused by hyperglycemia and overcome neuronal insulin resistance, providing new insights into the improvement of diabetes-related neuropathy [5].
Research Progress in the Treatment of Type 2 Diabetes
As a new type of hypoglycemic drug, Tirzepatid has become the first dual GIP/GLP-1R agonist approved for the treatment of diabetes in the United States. A number of large-scale clinical trials have confirmed its significant blood glucose lowering and weight loss effects, and it has the potential in cardiovascular protection. The concept of synthetic peptides has opened up many unknown possibilities for Tirzepatid. Ongoing trials (NCT04166773) and evidence suggest that it is a promising drug in the fields of non-alcoholic fatty liver disease (NAFLD), renal and neuroprotection [6](Ma Z, 2023).
Long-term Impact of Tirzepatid on Cardiovascular Health
Tirzepatid may reduce the risk of cardiovascular diseases by promoting weight loss. A study examined the impact of Tirzepatid on obesity and cardiovascular disease events in American adults [7]. The study found that among American adults eligible for Tirzepatid treatment, after treatment with 15 mg of Tirzepatid, an estimated 70.6% and 56.7% of adults lost ≥ 15% and ≥ 20% of their body weight respectively, which means a 58.8% reduction in the number of obese people. Among those without cardiovascular disease, the estimated 10-year cardiovascular disease risk decreased from 10.1% “before treatment” to 7.7% “after treatment”, with an absolute risk reduction of 2.4% and a relative risk reduction of 23.6%, preventing 2 million cardiovascular disease events.
In conclusion, Tirzepatid is a new type of dual agonist of GIP and GLP-1 receptors, which is of great significance in the treatment of type 2 diabetes and obesity. It can more effectively promote insulin secretion, inhibit glucagon secretion, precisely regulate blood glucose, reduce the risk of complications, improve the function of pancreatic beta cells, delay the progression of diabetes, and has a cardioprotective effect. In the treatment of obesity, it can effectively reduce food intake, lower appetite, increase satiety, help obese patients lose weight, and reduce the risk of obesity-related complications. It can also improve insulin resistance and lipid metabolism. In addition, it shows potential in the treatment of metabolic abnormal related diseases such as non-alcoholic steatohepatitis, sleep apnea syndrome, and heart failure, and can simultaneously improve multiple metabolic indicators, providing a more comprehensive treatment plan. Its once-weekly injection method is convenient to use and can improve patients’ treatment compliance. By effectively controlling blood glucose and weight and reducing the risk of complications, it can significantly improve patients’ physical condition, enhance their daily activity ability and quality of life, increase their confidence in disease control, reduce their psychological burden, and improve their social adaptability.
Scientific Journal Author
Dr. William T. Garvey is a distinguished scholar and researcher affiliated with multiple prestigious institutions, including the University of Alabama at Birmingham, Aston University, and the Birmingham Veterans Affairs Medical Center. His academic background and professional experience span a wide range of disciplines within the medical and scientific fields. Dr. Garvey has made significant contributions to the fields of endocrinology and metabolism, nutrition and dietetics, biochemistry and molecular biology, as well as general and internal medicine, with a particular focus on the cardiovascular system and cardiology. His work has been widely recognized and honored, notably being named a Highly Cited Researcher in the Cross-Field category for both 2023 and 2024, reflecting the substantial impact and influence of his research on the broader scientific community.
Dr. Garvey’s research interests and expertise extend to various aspects of metabolic diseases and their management. He has been actively involved in studying diabetes mellitus, obesity, and their associated complications, aiming to uncover novel therapeutic strategies and improve patient outcomes. His work encompasses basic scientific research, clinical trials, and translational studies, bridging the gap between laboratory findings and real-world medical applications. Through his extensive research, Dr. Garvey has contributed to a deeper understanding of the underlying mechanisms of metabolic disorders and has helped shape clinical guidelines and treatment protocols in the field of endocrinology and metabolism. Dr. William T. Garvey is listed in the reference of citation [4].
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