Skip to main content

How long does it take Fintepla to work?

Medically reviewed by Carmen Pope, BPharm. Last updated on July 12, 2022.

Official answer


On average, it takes 3 to 4 weeks for Fintepla (fenfluramine) to start working according to trials that investigated the use of Fintepla in children and adolescents aged two to 18 years with seizures associated with Dravet syndrome, and children and adults with Lennox-Gastault syndrome. Once a reduction in seizure frequency was observed, it generally persisted for the entire treatment period.

How effective is Fintepla?

Fintepla is significantly more effective than a placebo (a treatment that contains no active ingredient). Trials in children with Dravet syndrome reported a reduction in seizure frequency of between 31.7% and 70% depending on the dosage of Fintepla administered. Some participants reported no seizures at all during the trial period.

Two moderately large studies (one with 117 participants and one with 85 participants with Dravet syndrome) reported a statistically significant reduction in seizure frequency for participants administered Fintepla within three to four weeks of starting Fintepla. This effect was reported across all dose ranges and remained consistent over the study trial period (usually around 14 to 15 weeks).

  • Study 1 (117 participants) compared a 0.7 mg/kg/day and a 0.2 mg/kg/day dose of Fintepla with placebo in patients who were not receiving stiripentol. 98% of patients were taking between 1 and 4 other antiepileptic drugs. Seizure frequency decreased compared with placebo by 31.7% in those administered Fintepla 0.2 mg/kg/day and by 70% in those administered Fintepla 0.7 mg/kg/day. Three patients in both treatment groups reported no seizures within the 14-week treatment period.
  • Study 2 (N=85) reported a 59.5% reduction in seizure frequency in those assigned 0.4 mg/kg/day dose of Fintepla (these patients were also receiving stiripentol and either clobazam, valproate, or both). One patient in the treatment group reported no seizures within the 15-week treatment period.

For Lennox-Gastault Syndrome (LGS), a phase 3 trial reported a 23.7% reduction in monthly drop seizures in 263 patients with LGS (age 2-35 years) who were prescribed Fintepla at 0.7 mg/kg/day compared to 8.7% with placebo. Nearly one-quarter of those patients on Fintepla experienced at least a 50% reduction in drop seizure frequency per 28 days. In 18%, drop seizure frequency reduced by 50% to 75%, and in 6% drop seizure frequency reduced by at least 75%. The most common side effects reported were diarrhea, decreased appetite, fatigue, sleepiness, and vomiting.


Drug information

Related support groups