Public health agency the US Food and Drug Administration announced on Monday that it has authorised Ruzurgi (amifampridine) tablets, which is the first and only treatment of Lambert-Eaton myasthenic syndrome (LEMS) in patients six to less than 17 years of age, under its priority review, orphan drug and fast track designations.

LEMS is a rare autoimmune disorder where the body's own immune system attacks the neuromuscular junction (the connection between nerves and muscles) and disrupts the ability of nerve cells to send signals to muscle cells. The only other treatment approved for LEMS is only approved for use in adults.

The agency added that the use of Ruzurgi in patients six to less than 17 years of age is supported on evidence based on the adequate and well-controlled studies of the drug in adults with LEMS, pharmacokinetic data in adult patients, pharmacokinetic modeling and simulation to identify the dosing regimen in paediatric patients as well as the safety data from paediatric patients.

Effectiveness of Ruzurgi for the treatment of LEMS was established by a randomised, double-blind, placebo-controlled withdrawal study of 32 adult patients taking Ruzurgi for at least three months prior to entering the study. The effectiveness was measured by the degree of change in a test that assessed the time it took the patient to rise from a chair, walk three meteres and return to the chair for three consecutive laps without pause, concluded the agency.