Tirzepatide: Science, studies and safety data

Tirzepatide: scientific review of weight-loss efficacy and comparative analysis with semaglutide

Tirzepatide is a dual agonist of the GIP and GLP-1 receptors (the first of its class) and has been studied in type 2 diabetes (SURPASS programme) and in body weight (SURMOUNT programme). The molecule combines the effects of two incretin pathways, resulting in stronger regulation of appetite and glucose metabolism.

Effects on body weight

SURMOUNT-1 results (72 weeks)

• 5 mg: ~-15% weight loss

• 10 mg: ~-19.5%

• 15 mg: ~-20.9%
  
  
  

Long-term effect (88 weeks)

• Up to 25.3% mean weight loss compared with 9.9% with placebo.
  
  

Likelihood of weight loss ≥5/10/15%

• Tirzepatide significantly increases the likelihood of achieving ≥15% weight loss compared with semaglutide.
  
  

Other study data

Glycaemic control

• Tirzepatide resulted in a greater reduction in HbA1c compared with semaglutide 1 mg.

Cardiovascular and cognitive effects

• GLP-1 therapies, including tirzepatide, are associated with a reduced risk of stroke and dementia.

Weight maintenance

• 89.5% of participants maintained ≥80% of their weight loss during long-term follow-up.
  
  

Tirzepatide versus semaglutide: results

Clinical data (SURMOUNT-5)

• Mean weight loss after 72 weeks: 20% with tirzepatide versus 14% with semaglutide.

• Participants with ≥25% loss: 32% on tirzepatide versus 16% on semaglutide.

Tolerability and side effects

• Similar profile: most often nausea, diarrhoea, constipation.
  
  
  
  

Safety

• Common gastrointestinal effects: nausea, vomiting, diarrhoea.

• Possible risk of thyroid C-cell tumours (as with semaglutide).
  
  

Summary

Tirzepatide is a dual agonist of the GIP and GLP-1 receptors. In the head-to-head SURMOUNT-5 study it was associated with a greater mean reduction in body weight than semaglutide (20% versus 14% at 72 weeks). Research tirzepatide is intended exclusively for laboratory research and not for human use.

Frequently asked questions

What did the SURMOUNT-1 study show?

At 72 weeks the mean change in body weight was from ~−15% to ~−20.9%, depending on the study group, versus −3.1% with placebo.

How does it differ from semaglutide?

Tirzepatide activates two receptors (GIP and GLP-1), while semaglutide activates only GLP-1. In the head-to-head SURMOUNT-5 study the mean weight loss at 72 weeks was 20% versus 14%.

Is research tirzepatide an approved medicine?

No. Research tirzepatide is not an approved medicine; it is intended exclusively for laboratory research and not for human use.