Riluzole-induced interstitial lung disease is a rare and potentially life-threatening adverse event successfully treated with high-dose steroid therapy: Case reports and review of the literature.

Riluzole (RZ)-induced interstitial lung disease (RZ-ILD) is a rare and potentially life-threatening adverse event in amyotrophic lateral sclerosis (ALS) patients, which is rarely reported. Therefore, the optimal treatment for RZ-ILD is unclear. We describe herein three Japanese cases of ALS complicated with RZ-ILD, of which two were successfully treated with high-dose steroid therapy. In our all ALS cases with RZ-ILD, the duration of RZ exposure until RZ-ILD onset was within 2 months. All three cases showed respiratory symptoms, dorsal predominant ground-glass opacities by imaging analysis, and abnormal laboratory findings associated with interstitial lung diseases, such as Krebs von den Lungen-6 and surfactant protein-D. Intravenous high-dose steroid therapy together with the discontinuation of RZ in two cases with respiratory symptoms markedly ameliorated their symptoms and abnormal findings of RZ-ILD. One case showed mild respiratory symptoms compared with the others and recovered after the withdrawal of RZ only. According to previous case reports and our cases, RZ-ILD may develop 2 months after initiating RZ and exacerbate respiratory symptoms rapidly in ALS patients with severe respiratory muscle involvement or complicating aspiration pneumonia. Transient high-dose steroid therapy in addition to discontinuation of RZ might be a good therapeutic option for RZ-ILD.