1 Recommendations

1.1 Fenfluramine is recommended as an add‑on to other antiseizure medicines for treating seizures associated with Dravet syndrome in people aged 2 years and older, only if:

  • seizures have not been controlled after trying 2 or more antiseizure medicines

  • the frequency of convulsive seizures is checked every 6 months, and fenfluramine is stopped if it has not fallen by at least 30% compared with the 6 months before starting treatment

  • the company provides fenfluramine according to the commercial arrangement.

1.2 This recommendation is not intended to affect treatment with fenfluramine that was started in the NHS before this guidance was published. People having treatment outside this recommendation may continue without change to the funding arrangements in place for them before this guidance was published, until they and their NHS clinician consider it appropriate to stop. For children and young people, this decision should be made jointly by the clinician and the child or young person, or their parents or carers.

Why the committee made these recommendations

Treatment for Dravet syndrome often starts with a single antiseizure drug such as sodium valproate. Other treatments can then be added if seizures are not well controlled. In practice, standard care often involves a combination of 3 antiseizure medicines. Clinicians may offer add-on therapies such as cannabidiol with clobazam, or fenfluramine.

Clinical trial evidence shows that fenfluramine, when added to standard care medicines, reduces the number of convulsive seizures people have. And it may be more effective than cannabidiol plus clobazam in reducing the number of seizures when used with 2 other antiseizure medicines. There is some evidence that adding fenfluramine improves quality of life for people with Dravet syndrome and their carers compared with standard care medicines alone.

The cost-effectiveness estimates are within the range NICE considers an acceptable use of NHS resources. There is evidence that there are also likely to be benefits from fenfluramine beyond what was in the economic model. These include reducing how long seizures last for, fewer non-convulsive seizures, and quality of life benefits. So fenfluramine is recommended.

  • National Institute for Health and Care Excellence (NICE)