Author's addendum to the article: Fingolimod: Assay analysis of US generic capsule products reveals variation in fingolimod content beyond the recommended acceptance criteria.

Our article "Fingolimod: Assay analysis of US generic capsule products reveals variation in fingolimod content beyond the recommended acceptance criteria" highlighted the variation of active ingredient in generic fingolimod capsule products. This analysis was prompted by reports of clinical adverse events and/or multiple sclerosis relapse in patients following transition from Gilenya® fingolimod capsules (Novartis) to generic fingolimod capsule products. Further assay analysis functioned to both confirm previous out-of-specification findings, and to identify an additional generic product that failed to comply with United States Pharmacopeia (USP) recommendations.