Obesity is a global health concern associated with numerous complications, including type 2 diabetes, cardiovascular diseases, and certain cancers. Recent advancements in medical treatments have introduced injectable medications like Wegovy (semaglutide) and Mounjaro (tirzepatide) as effective options for weight management. This page provides detailed information on their method of action, along with combined insights on benefits, precautions, and potential side effects, supported by scientific evidence.
Method of Action
Wegovy (Semaglutide)
Wegovy contains semaglutide, a glucagon-like peptide-1 (GLP-1) receptor agonist. It mimics the action of the natural hormone GLP-1, which plays a crucial role in regulating appetite and food intake.
- Appetite Suppression: Semaglutide activates GLP-1 receptors in the brain, particularly in the hypothalamus, leading to reduced hunger and increased feelings of fullness.
- Delayed Gastric Emptying: It slows the rate at which food leaves the stomach, prolonging the sensation of satiety after meals.
- Enhanced Insulin Secretion: Stimulates insulin release from the pancreas in a glucose-dependent manner, aiding in blood sugar control.
- Inhibition of Glucagon Secretion: Reduces the release of glucagon, a hormone that raises blood glucose levels.
Evidence: A clinical trial published in the New England Journal of Medicine demonstrated that participants using semaglutide achieved a mean weight loss of 14.9% over 68 weeks compared to 2.4% with placebo (Wilding et al., 2021).
Mounjaro (Tirzepatide)
Mounjaro contains tirzepatide, a novel dual agonist that targets both glucose-dependent insulinotropic polypeptide (GIP) and GLP-1 receptors.
Similarities to Wegovy:
- GLP-1 Receptor Activation: Like semaglutide, tirzepatide activates GLP-1 receptors, resulting in appetite suppression, delayed gastric emptying, enhanced insulin secretion, and reduced glucagon levels.
- Appetite Regulation: Both medications reduce hunger and promote a feeling of fullness, aiding in weight loss.
Differences from Wegovy:
- GIP Receptor Activation: Tirzepatide uniquely stimulates GIP receptors, another incretin hormone involved in glucose and lipid metabolism.
- Enhanced Insulin Secretion: The activation of GIP receptors further boosts insulin release in response to food intake.
- Improved Metabolic Effects: GIP activity may contribute to additional weight loss and better glycemic control beyond what is achieved with GLP-1 activation alone.
- Potential for Greater Weight Loss: The dual mechanism may explain the superior weight reduction observed in clinical trials with tirzepatide compared to GLP-1 agonists alone.
Evidence: The SURMOUNT clinical trials reported that tirzepatide resulted in up to 22.5% weight reduction in participants over 72 weeks, surpassing results typically seen with GLP-1 receptor agonists alone (Jastreboff et al., 2022).
Benefits
Both Wegovy and Mounjaro offer significant benefits in weight management and metabolic health:
- Substantial Weight Loss:
- Wegovy: Users experienced an average weight loss of up to 14.9%.
- Mounjaro: Users saw weight reductions of up to 22.5%.
- Improved Glycemic Control: Beneficial for individuals with type 2 diabetes.
- Cardiovascular Benefits: May reduce risk factors associated with heart disease by improving lipid profiles and lowering blood pressure.
- Convenient Dosing: Both are administered once weekly via subcutaneous injection, enhancing adherence to the treatment regimen.
Precautions
While Wegovy and Mounjaro provide substantial benefits, certain precautions are necessary:
- Thyroid C-Cell Tumors: Contraindicated in individuals with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2.
- Pancreatitis Risk: Use cautiously in patients with a history of pancreatitis; both medications have been associated with cases of pancreatitis.
- Gastrointestinal Disorders: Caution is advised for patients with severe gastrointestinal diseases due to potential exacerbation of symptoms.
- Hypoglycemia: Increased risk when used with other glucose-lowering medications like insulin or sulfonylureas.
- Pregnancy and Breastfeeding: Not recommended during pregnancy or while breastfeeding due to potential risks to the foetus or infant.
- Renal Impairment: Monitor kidney function, especially in patients experiencing adverse gastrointestinal reactions that could lead to dehydration.
- Oral Contraceptive Pill: Women using oral contraceptives should be aware that there is a theoretical risk that their absorption may be delayed and have less effect than expected. Alternative or additional methods of contraception are recommended to reduce the chances of pregnancy.
Potential Side Effects
Users of Wegovy and Mounjaro may experience side effects, which are generally similar due to their related mechanisms of action:
Common Side Effects:
- Gastrointestinal Symptoms:
- Nausea
- Diarrhoea
- Vomiting
- Constipation
- Abdominal pain
- Decreased appetite
- Injection Site Reactions:
Serious Side Effects (< 1%):
- Pancreatitis: Severe abdominal pain that may radiate to the back, accompanied by nausea and vomiting.
- Gallbladder Disease: Including gallstones and inflammation of the gallbladder (cholecystitis).
- Kidney Problems: Acute kidney injury can occur, particularly in patients who experience dehydration due to gastrointestinal side effects.
- Thyroid Tumors: Risk of developing thyroid C-cell tumors; report symptoms like a lump in the neck, hoarseness, or difficulty swallowing. There has been no human case of thyroid cancer, but thyroid cancer has occurred in animal studies.
- Allergic Reactions: Signs include rash, itching, rapid heartbeat, swelling of the face or throat, and difficulty breathing.
Summary
Wegovy and Mounjaro represent significant advancements in obesity treatment, offering substantial benefits in weight reduction and metabolic health improvement. Wegovy acts as a GLP-1 receptor agonist to suppress appetite and enhance insulin secretion, while Mounjaro builds upon this mechanism by also activating GIP receptors, potentially leading to greater weight loss and improved glycaemic control. However, both medications come with potential risks and side effects that necessitate careful consideration and medical supervision. A thorough evaluation by a healthcare professional is essential to determine suitability and to monitor treatment.
Patient Consent
Patient Acknowledgment and Consent for Weight Loss Injections
I hereby acknowledge that:
- I have read and understood the information provided about Wegovy (semaglutide) and Mounjaro (tirzepatide) weight loss injections.
- I understand the methods of action of these medications, including how they may aid in weight loss and improve metabolic health.
- I am aware of the benefits associated with these treatments, such as significant weight loss, improved glycaemic control, and potential cardiovascular benefits.
- I have been informed about the precautions, including contraindications and the importance of clinical supervision during treatment.
- I understand the potential side effects, both common and serious, that may occur with the use of these medications.
- I agree to inform my healthcare provider of any changes in my medical condition or if I experience any adverse effects during the course of treatment.
By signing below, I voluntarily consent to initiate treatment with weight loss injections. I acknowledge that I am making an informed choice based on the information provided. I understand that I can seek further information and clarification from this service.
