NHS pharmacist warns summer heat could make 1 popular drug less effective

An NHS pharmacist has warned that soaring summer temperatures could make the popular weight-loss drug Mounjaro less effective. The weekly injection must be kept away from direct sunlight and stored below 30C once it is in use, as excessive heat could damage the medicine.

Peter Thnoia, a weight-loss pharmacist at NHS pharmacy PillTime, said users should take extra care over where they keep their pens during hot weather. He warned that prolonged exposure to high temperatures could see the drug lose its effectiveness. Mr Thnoia told the Sun: “My advice is simple: if you’re staying at home during the hot weather, keep your pens somewhere cool like the fridge.”

He added: “With the injections being once a week, I would always recommend people stick to their set day and take them when it is convenient, rather than travel with them.

“Whether that’s the morning or afternoon doesn’t matter – small changes to the time of day when they are taken won’t make a difference to the medication’s effectiveness.”

Mounjaro and other glucagon-like peptide-1 receptor agonist (GLP-1) drugs, including Wegovy and Ozempic are used to treat obesity and type 2 diabetes, however research has suggested that their use can bring wider health benefits.

In a recent study, researchers looked at GLP-1 use and whether the drugs were linked to a reduced risk of obesity-associated cancers.

Experts from the United States examined data on more than 161,000 patients who were obese, did not have diabetes and had not been diagnosed with an obesity-related cancer.

Of these, half used weight-loss injections while the other half were given consultation on diet and exercise.

The average age of people in the study was 47 and they were followed up for two years.

The analysis, published in the Annals of Oncology, revealed that those who took GLP-1s were significantly less likely to be diagnosed with an obesity-related cancer during the follow-up period, with a reduced risk of 41%.

The data revealed the size of the reduction was not found among black people.

“Our study found that over an average follow-up of two years, GLP-1 RA use was associated with a significantly lower incidence of cancers directly fuelled by excess body weight,” said the senior author of the study, Dr Aparna Kamat, director of the Division of Gynaecologic Oncology at Houston Methodist Hospital in Texas.