Patient suffers torn oesophagus after using unapproved peptide

The medicines regulator has revealed a patient suffered a torn oesophagus after using an unapproved weight-loss peptide labelled as retatrutide.

Laboratory testing found the product contained no retatrutide, but instead a high dose of undeclared weight-loss drug semaglutide.

Retatrutide is currently undergoing clinical trials in humans and has not been approved by the Therapeutic Goods Administration.

A patient who used an unapproved peptide labelled as the weight-loss drug retatrutide has suffered a potentially fatal torn oesophagus.

The medicines regulator, the Therapeutic Goods Administration (TGA), has revealed details of the case to the ABC as part of its latest warning against the use of unapproved peptides.

It said the peptide user experienced uncontrollable vomiting and required hospitalisation.

The TGA said laboratory testing found the product contained no retatrutide, but instead had undeclared semaglutide, the drug used in weight-loss drugs Ozempic and Wegovy.

"The amount of semaglutide detected was approximately eight times higher than the level found in semaglutide products assessed by the TGA," the regulator's safety advisory said.

The results follow testing by the ABC in partnership with the University of Queensland, which found vials of black market retatrutide had much higher doses than declared on their labels.

Melbourne gastroenterologist Darcy Holt has treated patients who have suffered adverse effects from injecting unapproved counterfeit retatrutide.

He said a torn oesophagus, which is the tube that carries food and liquid to a person's stomach, was a medical emergency.

"A tear of the oesophagus can mean that stomach contents can enter the part of the body where the heart and main blood vessels are, and infection and inflammation in that area are extremely serious.

"Many of the peptides we are talking about do have gastrointestinal effects and require titration of dose to minimise those effects.

"But in overdose, the gastrointestinal effects can be severe. A high dose of the drug can cause extreme nausea and forceful vomiting leading to an oesophageal tear."