The manufacturer of the weight loss drug Mounjaro has paused shipments to the UK ahead of a significant price rise for the treatment due to come into effect next month.
The US pharmaceutical company Eli Lilly is due to increase the UK list price of the drug by up to 170% from September amid a White House push to get drugmakers to raise medicine prices in Europe to allow for price cuts in the US.
The company said that in order to manage its supply and ensure that patients maintained access, it had allocations in place for pharmacies and providers that ordered medicines from the company.
There were legal protections in place to prevent inappropriate stockpiling of medicines by providers, Lilly said. It plans to resume orders on 1 September.
The rise in prices could result in a month's supply of the highest dose of the medicine increasing from £122 to £330 ($165 to $445).
Lilly has reportedly told its two British wholesalers to temporarily stop taking orders after demand soared before the price increase comes into force on 1 September. Pharmacies have said there has been panic buying of the drug since the price announcement earlier this month.
People using Mounjaro have been warned against switching to black market sellers or bulk buying.
While many pay for Mounjaro in the UK, it became available on the NHS at the end of June, and Lilly says the higher price will not affect those who get it through the health service.
The drug - also known by its generic name tirzepatide - has become a popular alternative to the most well-known weight loss drug, Ozempic. Both drugs, which are taken as weekly injections, were developed as treatments for type 2 diabetes.
When it was launched in Britain in February 2024, Lilly agreed to a list price "significantly below" its other European markets to stop delays in availability of the medicine through the NHS.
The increase in the list price will align it "more consistently", the company has said, although it added that the NHS would not pay the new, higher price to ensure continued access for people with obesity and type 2 diabetes receiving it through the health service.
On 31 July, Donald Trump sent letters to 17 of the world's biggest drugmakers, including Eli Lilly and Novo Nordisk, demanding cuts to drug prices for Americans within 60 days. In May, the US president told reporters that a friend in London had told him he had bought the "fat shot drug" for $88, compared with $1,300 in New York.