A country estate near Northampton has become the centre of the largest ever seizure of unlicensed weight-loss medicines in the UK.

Two men aged 29 were arrested during a raid in which the Medicines and Healthcare products Regulatory Agency (MHRA) recovered about 12,000 doses of unlicensed weight-loss medicines.

Law enforcement officers uncovered what they described as a large-scale facility used to manufacture, assemble and distribute unlicensed products including retatrutide, an unlicensed weight-loss drug, as well as tirzepatide, sold under the brand name Mounjaro, and other peptide-based medicines.

Andy Morling, the head of the MHRA’s criminal enforcement unit, said the operation demonstrated the agency’s “unwavering commitment to ensuring there is no hiding place for those who cynically put the public’s health at risk for profit”.

He said: “Medicines regulation isn’t discretionary – it exists to protect people. That’s why we continue to target the traffickers who seek to bypass that protection, taking down the infrastructure that supports them and creating a hostile environment for their exploitative and harmful trade. In addition to disrupting an organised criminal group, I’m confident that dismantling this illicit production facility will have prevented significant public harm.”

The property was raided on 28 May with the support of Northamptonshire police, a press release said. Investigators believe the country estate was being used as a large-scale site to manufacture, assemble and distribute the weight-loss drugs. Officers said they had seized substantial quantities of packaging materials along with what are believed to be pharmaceutical substances used in the illicit production of the medicines.

In November last year, the MHRA warned that organised crime gangs had begun manufacturing their own branded weight-loss drugs designed to resemble legitimate medicines, in what authorities described as a significant threat.

The agency said the new production model “gives customers a false sense of security in thinking they are buying a genuine product”.

The first raid on an illegal weight-loss drug factory took place in Northampton in October 2025. During that operation, the MHRA seized tens of thousands of empty weight-loss pens ready to be filled, raw chemical ingredients, and more than 2,000 unlicensed retatrutide and tirzepatide pens due to be sent to customers. There were no arrests.