Adalimumab and myositis: A case report and review of the French and international Pharmacovigilance Databases

TNFα inhibitors, including adalimumab, are widely used in inflammatory rheumatologic and bowel diseases. Well-known adverse effects include: opportunistic infections, immunogenicity and new inflammatory manifestations. Myositis is an inflammatory disease, which manifests with muscle symptoms and can be life-threatening. Little is known about drug-induced myositis. We aimed to describe a case of myositis induced by adalimumab and reviewed national and international pharmacovigilance databases for other cases until 01/02/2019. This was a 63 years old woman with Crohn's disease, who developed muscle weakness, and rhabdomyolysis 3 months after starting adalimumab. Diagnosis of myositis was suspected and confirmed with electromyography and muscle biopsy. Improvement in muscle symptoms was observed after stopping adalimumab and starting corticosteroids. Muscular adverse effects are well-known and usually benign with adalimumab. However, five cases of myositis during treatment with adalimumab were registered in French PharmacoVigilance Database (FPVD) with muscle symptoms observed 3 months to 7 years after starting adalimumab. In VigiBase^Ⓡ, 90 cases of myositis associated with adalimumab with some similar characteristics were registered. When a patient treated with adalimumab complains of muscular symptoms, inflammatory myopathies should be considered. This adverse effect should be mentioned in a 'Summary of Product Characteristics' to alert healthcare professionals.