Zepbound – Overview


  • Zepbound is an obesity medication which has the active ingredient Tirzepatide and is manufactured by Eli Lilly.


  • Originally, Tirzepatide was developed and prescribed for the treatment of Diabetes under the brand name Mounjaro.


  • However, the maufacturer tested increasing the dosage levels, and discovered that it lead to significant weight reduction.


  • Zepbound was approved for weight-loss use in the USA and the UK in November 2023.


  • Zepbound is intended for adults with a body mass index greater than 30, or greater than 27 with an obesity-related medical condition (i.e. diabetes, high blood pressure, high cholesterol, sleep apnea) and as an adjunct to a reduced calorie diet and increased physical activity for chronic weight management.


  • Zepbound is a drug treatment which is intended to continue for the rest of a patient’s life.


  • In the USA, a four-week course of Zepbound costs $1,060 a month. That compares with a list price of $1,349 per-four-week course for Novo Nordisk’s weight-loss drug Wegovy.



Zepbound® - Dosing Schedule

Zepbound® - General Information




Zepbound is an obesity medication which has the active ingredient Tirzepatide and is manufactured by Eli Lilly.

The active ingredient, tirzepatide, activates two hormonal receptors (GIP and GLP-1). When these naturally occurring hormones are mimicked, your appetite is suppressed, blood sugar is better regulated and the rate at which food leaves the stomach is reduced. All of these actions result in weight loss.

Zepbound weight loss in patients with obesity or overweight



Without type 2 diabetes

Zepbound, approved for chronic weight loss, was evaluated in the SURMONT-1 and SURMONT-2 clinical studies.


The Phase 3 SURMONT-1 study compared weight loss with tirzepatide (Zepbound) to a placebo (inactive) treatment over a 72-week period. Patients did not have a diagnosis of type 2 diabetes.


  • The research included more than 2,500 obese adults or overweight adults with at least one comorbidity (high blood pressure, high cholesterol, obstructive sleep apnea or heart disease).


  • Patients taking tirzepatide started at a dose of 2.5 mg once-weekly and then increased the dose by 2.5 mg at four-week intervals to reach their final dose. Final maintenance doses were set at 5 mg, 10 mg, or 15 mg. The dose escalation period was 20 weeks.


  • During the study, participants also received counseling on a reduced-calorie diet and exercise as an adjunct treatment.


The study co-endpoints were the percentage change in weight (with the 10 mg and/or 15 mg dose) from the start of the study (baseline) and the percentage of participants with a weight loss of 5% or more at 72 weeks, compared to placebo. At the start of the study, the mean weight of participants was 104.8 kg (230.6 lb) with a mean body mass index (BMI) of 38.


All of the study endpoints were met. Weight loss with all three doses as compared to placebo was statistically significant. At the end of the 72-week study, the mean percent (%) weight loss and average weight loss with tirzepatide (Zepbound) was:


  • 15% for the 5 mg dose (about a 16 kg [35 lb] weight loss)
  • 19.5% for the 10 mg dose (about a 20 kg [45 lb] weight loss)
  • 20.9% for the 15 mg dose (about a 22 kg [48 lb] weight loss)
  • 3.1% for placebo (about a 3 kg [7 lb] weight loss)


The percentage of patients with a weight loss of 5% or more was 85% to 91% based on dose, compared to 35% with placebo. In addition, 50% to 57% of patients achieved a weight reduction of 20% or more (with the 10 to 15 mg dose) as compared to 3% in the placebo group.


People in the study were able to maintain the weight reduction for the full 72-week study period. At the highest dose, a decrease in waist circumference of 14.5 centimeters (5.7 inches), when adjusted for placebo, was recorded, as well as improvements in blood glucose, cholesterol levels and blood pressure.


The most common side effects were mild-to-moderate nausea, diarrhea and constipation and occurred primarily during the dose escalation period. Treatment discontinuation due to side effects occurred in up to 6.7% of those receiving Zepbound (primary in the first few months due to stomach side effects) and 3.4 % for the placebo group.



With type 2 diabetes

The Phase 3 SURMONT-2 study compared weight loss with tirzepatide (Zepbound) to a placebo (inactive) treatment over a 72-week period. Patients with obesity or overweight did have a diagnosis of type 2 diabetes with an HbA1c of 7% to 10%.


Patients were randomized to receive Zepbound 10 mg, Zepbound 15 mg, or placebo once weekly. Mean body weight at the start of the study was was 100.7 kg (45.8 kg), and enrolled patients also had comorbidities such as high blood pressure, high lipids levels, obstructive sleep apnea, or heart disease.


Weight loss with both Zepbound doses as compared to placebo was statistically significant. Over the 72-week period the mean percent (%) weight loss with tirzepatide (Zepbound) in patients with type 2 diabetes was:


  • 12.8% loss for the 10 mg dose (5.9 kg [12.9 lb])
  • 14.7% for the 15 mg dose (6.7 kg [14.8 lb])
  • 3.2% for placebo (1.5 kg [3.2 lb])


The percentage of patients with a weight loss of 5% or more was 79% to 83% based on dose, compared to 33% with placebo.

Zepbound can be used by adults ages 18-75 who have:


  • A BMI of 30 or above
  • A BMI of 27 or above and you have a weight-related health condition such as:
  • Asthma
  • Cardiovascular disease
  • Depression
  • Fatty liver disease
  • Gallbladder disease
  • High blood pressure
  • History of certain cancers
  • Osteoarthritis or gout
  • PCOS
  • Sleep apnoea


You won’t be able to take Zepbound® if you:

  • Are over 75
  • Are pregnant or breastfeeding
  • Have liver, kidney or heart failure, an eating disorder or pancreatitis
    Are taking insulin, sulphonylureas or other weight loss drugs that work in the same way as Zepbound, e.g. Victoza.

You inject Zepbound® just once a week into your tummy, thigh or upper arm.



Zepbound® injections come in a variety of doses. Depending on where you are in your Zepbound® journey, you will need to take a different dose.


The dose is gradually increased to make sure you cope with any potential side effects until you get to a maintenance dose, this process is known as titration.


If all goes to plan and you can tolerate the treatment, the dosing schedule will be as follows:


  • Weeks 1-4:    2.5mg weekly
  • Weeks 5-8:   5.0mg weekly
  • Weeks 9-12:  7.5mg weekly
  • Weeks 13-16: 10.0mg weekly
  • Weeks 17 onwards:  15.0mg weekly

Zepbound® has been shown to be an effective weight loss treatment, when used alongside a reduced-calorie diet and increased physical activity.  


Patients should be able to register initial weight-loss within the first 2 to 4 weeks.

Like all medications, some people might feel some side effects from taking Zepbound®. It’s thought that more than one in 10 people might experience headaches, vomiting, diarrhoea, constipation, tummy ache or nausea. 


Some people might also experience dizzy spells, indigestion and bloating among other symptoms. Find out more by reading the patient information leaflet here.

Any Zepbound® pens that haven’t been opened should be kept in the fridge. During use you can keep the pens for 6 weeks in the fridge or room temperature (below 30°C).


Pens need to be disposed of in the sharps bin you’re given when you start your treatment. When you’re prescribed Zepbound® we’ll let you know how to get rid of the sharps bin and its contents.

Ideally, Zepbound should be kept refrigerated between 36°F to 46°F( 2°C to 8°C). Zepbound can remain for up to 28 days at room temperature (46°F to 86°F, or 8°C to 30°C).


When traveling with Zepbound, keep Zepbound in its original carton and avoid exposing it to direct sunlight or extreme temperatures.