The MHRA said on Thursday it has proposed more frequent heart and blood monitoring for Duchenne patients taking Duvyzat after reports of deaths abroad.
The regulator said there have been several reports internationally of deaths in people with Duchenne muscular dystrophy while being treated with Duvyzat (givinostat). A small number of deaths have been reported outside the UK, and none in the UK.
After reviewing the cases and associated evidence, the MHRA has proposed updates to the product information. It is issuing interim monitoring advice based on those proposals, pending an independent review and finalisation of its position.
Doctors should obtain ECGs before treatment starts, within 2 to 4 weeks of starting givinostat, and then every 6 months, in line with Duchenne Care UK (North Star) clinical guidance.
The MHRA adds that 24-hour ambulatory ECG monitoring should be carried out at baseline and repeated once the patient is on a stable dose.
Serum electrolytes, including potassium, magnesium and calcium, should be checked as often as routine blood counts: every 2 weeks for the first 2 months, at month 3, and every 3 months after that.
Prescribers should continue to avoid Duvyzat in patients at increased risk of ventricular arrhythmias. The MHRA lists congenital long QT syndrome, coronary artery disease, electrolyte disturbances and the use of other medicines known to prolong the QT interval. Duvyzat can itself prolong QTc.
Healthcare professionals are asked to tell patients that the proposed changes aim to keep the medicine “as safe as possible” for everyone with Duchenne muscular dystrophy.
Patients should carry on taking Duvyzat as prescribed and attend all appointments. They should tell their doctor about any other medicines they take, or any changes to them, and talk to their specialist Duchenne team if they have concerns.
The MHRA first flagged the deaths in November 2025, when the company that holds the UK marketing authorisation, Italfarmaco, sent a letter to healthcare professionals at the regulator’s request.
The MHRA said then that it was reviewing the cases and would seek advice from the Commission on Human Medicines.
In that earlier letter, Italfarmaco said it had concluded the deaths were not related to givinostat or to one of its known side effects, and that it had assessed the balance of benefit and risk as unchanged.
The deaths included sudden deaths reported in clinical trials, expanded access programmes and after approval.
The medicine is conditionally approved in the UK for Duchenne muscular dystrophy in patients aged 6 and over.
The company’s 2025 reminder of existing monitoring covered blood counts on the same schedule now proposed for electrolytes, and ECGs for patients with underlying heart disease or those taking QT-prolonging medicines. The new proposals extend ECG checks to every patient, on a fixed timetable.
The MHRA said its licensing authority has reached a decision on the review, including more frequent ECG and electrolyte measurements, but implementation is subject to the independent review.
It will consider that report before any amendment to the product information is made, and will publish a further update once changes are final.
Duvyzat is a black triangle medicine, which means it is under additional monitoring. The MHRA asks healthcare professionals, patients and carers to report all suspected adverse reactions through the Yellow Card website, the Yellow Card app, or some clinical IT systems including EMIS and SystmOne.