Tirzepatide: what the research shows

What tirzepatide is

Tirzepatide, development code LY3298176, is a synthetic peptide that activates two receptors: the glucose-dependent insulinotropic polypeptide (GIP) receptor and the glucagon-like peptide-1 (GLP-1) receptor. It was developed by Eli Lilly and Company. [1] [2] [4]

GIP and GLP-1 are hormones released by the intestine. The FDA describes tirzepatide as activating the receptors of these two hormones to reduce appetite and food intake. [5]

How it has been studied

Tirzepatide was tested in two large phase 3 programmes: SURPASS in type 2 diabetes and SURMOUNT in obesity. The trials below were funded by Eli Lilly. [1] [2] [3]

SURPASS-2 compared tirzepatide head to head with semaglutide, a GLP-1 receptor agonist, in people with type 2 diabetes: at all three doses tested, tirzepatide was non-inferior and superior to semaglutide for the change in HbA1c, and body-weight reductions were also larger. [1]

Safety findings reported so far

The most common adverse events were gastrointestinal, mostly mild to moderate and occurring mainly while the dose was being increased. In SURMOUNT-1, adverse events led to stopping treatment in 4.3% to 7.1% of participants on tirzepatide and 2.6% on placebo. [2]

In SURPASS-2, serious adverse events were reported in 5% to 7% of participants on tirzepatide and 3% on semaglutide; nausea, diarrhoea and vomiting were the most frequent complaints in both groups. The three-year SURMOUNT-1 analysis found no new safety signals. [1] [3]

According to the FDA, tirzepatide causes thyroid C-cell tumours in rats, and it is unknown whether it causes such tumours, including medullary thyroid cancer, in humans. [5]

Regulatory status

Tirzepatide is the active ingredient of prescription medicines approved in the United States: first for blood-sugar control in adults with type 2 diabetes and, since 8 November 2023, for chronic weight management in adults with obesity, or overweight with at least one weight-related condition. [5]

An approved medicine is a finished product made and tested for patients and dispensed on prescription. The FDA has warned companies that sold semaglutide, tirzepatide or retatrutide directly to consumers for human use, with dosing instructions, while labelling the products ‘for research purposes’ or ‘not for human consumption’. Research material is not a medicine: it has not been reviewed for safety, effectiveness or quality in people and must not be used in people. We sell tirzepatide only for in vitro laboratory research, without instructions for use. [6]

Storage and stability in the lab

Peptides can degrade through chemical routes such as oxidation, deamidation and hydrolysis and through physical routes such as aggregation, and they are generally more stable in the dry state than in solution. [7]

Lyophilised vials are therefore normally kept cold, dry and away from light until they are reconstituted. The storage statement on the product page and on the batch certificate takes precedence.

How to check a batch

A useful certificate of analysis names the testing laboratory, the batch number printed on the vial, the test date and the methods used. Identity is usually confirmed by mass spectrometry, where the measured mass should match the expected molecular mass, and purity is measured by HPLC.

Where the manufacturer supplies a batch report, we link it on the product page; products without one do not claim one.