Mounjaro (tirzepatide) in the treatment of obesity

What is Mounjaro (tirzepatide) and how does it work in the body?

Mounjaro contains the active substance tirzepatide, which belongs to a newer class of drugs and acts as a so-called dual agonist. It activates both GLP-1 and GIP receptors, which are involved in the regulation of appetite, energy intake, and blood sugar.

Upon food intake, incretin hormones are naturally released from the intestine, signaling to the brain that energy has been supplied to the body. Tirzepatide mimics and enhances the effect of two of these hormones: GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide).

Activation of these systems leads to several interacting effects:

• Reduced appetite and increased satiety: The medication affects central mechanisms for appetite regulation, which can contribute to reduced energy intake.
• Delayed gastric emptying: Gastric emptying is delayed, which can provide a more long-lasting feeling of fullness after a meal.
• Improved blood sugar control: Tirzepatide stimulates insulin release in a glucose-dependent manner and contributes to more stable blood sugar levels.

Mounjaro is approved for the treatment of type 2 diabetes with insufficient glycemic control, as well as for weight management in adults with obesity (BMI over 30) or overweight (BMI over 27) in the presence of at least one weight-related complication.

How the Mounjaro Kwikpen works

Mounjaro KwikPen is a pre-filled multi-dose pen designed to enable safe and simple self-administration of the medication at home, following instruction from a healthcare provider.

Unlike single-dose pens, the KwikPen contains several doses in the same unit. The pen is used for repeated injection occasions over a limited period of time, and a new, sterile disposable needle must be attached before each injection.

The medication is administered as a subcutaneous injection once per week. The injection is given in the subcutaneous fat, usually in the abdomen (at a distance from the navel), the upper part of the leg (thigh), or the back of the upper arm. It is recommended to rotate the injection site between doses to reduce the risk of local skin irritation.

Administration of Mounjaro – solution in a pre-filled injection pen

The medication is provided as a ready-to-use injectable solution in a pre-filled injection pen.

Before injection, it is important to wash your hands and check the solution through the pen's window. The liquid should be clear and colorless to slightly yellow. If it is cloudy or contains particles, the pen should not be used.

The dose is set using a dose selector. Once the correct dose is set, the needle is inserted into the skin and the injection button is pressed. It is important to keep the button pressed down and let the needle remain in the skin for at least about 5–10 seconds after the dose counter has returned to zero. This reduces the risk of part of the dose leaking out and ensures that the entire dose is administered correctly.

Dosage of Mounjaro

Treatment with Mounjaro (tirzepatide) begins with a low starting dose, usually 2.5 mg once per week during the first four weeks. Thereafter, the dose can be adjusted stepwise based on treatment response and tolerability.

The gradual dose escalation aims to improve tolerability, especially regarding gastrointestinal-related side effects. A dose increase that is too rapid can otherwise increase the risk of, for example, nausea.

The treatment is adapted individually to achieve the desired effect with the best possible tolerance.

A typical treatment schedule may include:

• Starting phase: 2.5 mg once per week for approximately 4 weeks
• Continued treatment: the dose can thereafter be increased to 5 mg per week
• If necessary: further dose adjustments (e.g., 7.5 mg, 10 mg, 12.5 mg, or 15 mg per week) can be considered based on individual effect and tolerability

Not all patients need to reach the highest dose. Dose increases occur only when further effect is deemed necessary and the treatment is well tolerated.

The treatment should always be used as a supplement to lifestyle measures, such as dietary changes and regular physical activity, and take place under medical supervision.

What results can be expected from Mounjaro?

In clinical studies, such as SURMOUNT-1, treatment with tirzepatide (Mounjaro) has shown a significant average weight loss in people with obesity or overweight. At higher dose levels, an average weight reduction of up to approximately 20 percent of body weight has been observed after about 72 weeks of treatment.

The results show that medical treatment can provide extensive weight loss and simultaneously contribute to improvements in several cardiometabolic risk factors, such as blood pressure, blood lipids, and blood sugar.

However, it is important to emphasize that treatment response varies between individuals, and not everyone achieves the same degree of weight loss. For the best and most sustainable results, it is recommended that the treatment be combined with long-term changes in dietary habits and physical activity.

Side effects of Mounjaro and how to manage them

The most common side effects during treatment with Mounjaro are gastrointestinal and include nausea, vomiting, diarrhea, constipation, and fatigue. These symptoms are usually mild to moderate and generally subside as the body adapts to the treatment.

The discomfort can often be alleviated through simple adjustments in daily life:

• Reduce portion sizes: Eat smaller meals and stop at early satiety signals.
• Avoid fatty and heavy food: High-fat and hard-to-digest food can enhance gastrointestinal symptoms.
• Ensure sufficient fluid intake: Regular fluid intake can help counteract constipation.

It is important to read the information in the package leaflet and to contact a healthcare provider in case of persistent or bothersome symptoms.

In rare cases, serious side effects have been reported, such as pancreatitis. In the event of symptoms such as persistent and severe abdominal pain, with or without radiation toward the back, a medical assessment must be made and the treatment re-evaluated.

Preserve muscle mass during your weight loss

To promote a healthy body composition during weight loss, it is important to combine the treatment with a sufficient protein intake and regular strength training. The goal is to preserve muscle mass as much as possible while fat mass decreases.

Treatment with Mounjaro can support a reduced energy intake. During an energy deficit, the body uses both fat and muscle tissue as an energy source. Without sufficient protein intake and muscle-stimulating activity, a larger part of the weight loss may therefore consist of loss of muscle mass.

Strength training serves as a signal to the body to preserve the musculature, while protein provides the building blocks required to maintain and repair muscle tissue.

Preserved muscle mass is also important for basal energy expenditure, which can facilitate weight stability over time.

What happens when you stop Mounjaro?

When treatment with Mounjaro is discontinued, the medication's effect on appetite and satiety signals ceases. This can lead to hunger increasing again, which for many means an increased risk of weight regain.

Obesity is regarded as a chronic disease where the body has biological mechanisms that counteract weight loss and promote weight regain. Studies of incretin-based medications show that part of the lost weight is often regained after treatment is discontinued, although the extent varies between individuals.

For some patients, a long-term treatment strategy may therefore be relevant. This can involve continued medication, sometimes at a lower dose, in combination with sustainable lifestyle habits such as dietary changes and regular physical activity.

Decisions on how the treatment should be discontinued or continued should always be made in consultation with the treating physician.

Frequently asked questions about Mounjaro

Is it legal to buy Mounjaro without a prescription?

Mounjaro is a prescription medication within the EU and may only be prescribed by licensed healthcare professionals following a medical assessment. Buying medication via unregulated or unauthorized websites involves significant risks. The products may be counterfeit, incorrectly dosed, or lack quality control, which can lead to serious health consequences.

What happens if I forget my dose of Mounjaro one week?

If you miss a dose, you should take it as soon as possible, provided that no more than 4 nights (4 days) have passed since the dose should have been taken. If more than 4 days have passed, skip the missed dose and take the next dose on your regular day. Do not take a double dose to compensate for a missed injection. In case of uncertainty, contact your doctor or pharmacist.

How long does a Mounjaro KwikPen last outside the refrigerator?

An unopened Mounjaro KwikPen should be stored in a refrigerator (2–8 °C) until first use. After first use, the pen can be stored at room temperature (maximum 30 °C) for up to 30 days. It must thereafter be discarded, even if medication remains. The medication must not be frozen.

Can one drink alcohol during treatment with Mounjaro?

Alcohol can generally be consumed in moderate amounts during treatment with Mounjaro, but should be consumed with caution. Tirzepatide affects gastrointestinal function and can delay gastric emptying, which in some individuals can enhance side effects such as nausea, vomiting, or stomach discomfort. Alcohol can further contribute to these symptoms. For people with type 2 diabetes, it is also important to be aware that alcohol can affect blood sugar levels. It is therefore recommended to limit intake and pay attention to how the body reacts.

Do I need to take obesity medication for life?

How long the treatment needs to continue is individual. Since obesity is a chronic disease, many may need a long-term treatment strategy to maintain their weight loss. For some, this means continued treatment, sometimes at a lower maintenance dose, similar to other chronic conditions such as high blood pressure. Treatment duration and plan are evaluated continuously in consultation with your doctor.

Sources

The New England Journal of Medicine.
Tirzepatide Once Weekly for the Treatment of Obesity.
https://www.nejm.org/doi/full/10.1056/NEJMoa2206038

The New England Journal of Medicine.
Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes.
https://www.nejm.org/doi/full/10.1056/NEJMoa2107519

EMA – European Medicines Agency (produktresumé) European Medicines Agency.
Mounjaro (tirzepatide) – EPAR product information.
https://www.ema.europa.eu/en/medicines/human/EPAR/mounjaro

Journal of the American Medical Association. Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity: The SURMOUNT-4 Randomized Clinical Trial
https://pubmed.ncbi.nlm.nih.gov/38078870/