(564) Erythema Multiforme and Tizanidine: A Rare Association

Introduction: Tizanidine is an alpha-2-receptor agonist FDA-approved for the management of muscle spasticity, such as multiple sclerosis (MS) or spasticity secondary to injury of the central nervous system. Tizanidine has many common adverse drug reactions (ADR) ranging from neurological (asthenia, dizziness, drowsiness), to gastrointestinal (xerostomia, constipation, vomiting) to psychiatric (delusions, nervousness, visual hallucinations). However, mucocutaneous ADRs to tizanidine are exceedingly rare, only reported in post-marketing analyses. They include Steven-Johnson Syndrome (SJS) and dermatitis. We report a case of erythema multiforme (EM), a mucocutaneous hypersensitivity rash, developing after completing a course of tizanidine- which to our knowledge has not yet been reported in literature.

Description: A 56 y.o. female with history of MS, lupus, hypertension, rheumatoid arthritis, hypothyroidism, Sjogren's syndrome, Raynaud's, chronic pain, and chronically bedbound presented with an erythematous rash bilaterally on her upper extremities one week after completing a 30-day course of tizanidine for her MS. She initially sought treatment at a dermatology clinic that biopsied this rash and prescribed topical antibiotics and steroids. The rash continued to progress to her torso, back, and lower extremities, then blistered and ulcerated. The patient presented to an outside hospital, was evaluated, and transferred to our facility for dermatology consultation for concerns of SJS. During this admission, the rash continued to spread to the vaginal area and was described as “circular pink macules with a central dusky hue and overlying scale coalescing into patches on the face, trunk, and extremities.” Biopsy from the outpatient dermatology clinic returned as EM. The rash improved with the administration of solumedrol and eventually resolved with an extended taper of oral prednisone.

Discussion: Tizanidine is a common drug that rarely causes dermatologic ADRs. This case demonstrates a potentially newly documented mucocutaneous rash ADR as a result of tizanidine administration. While rare, tizanidine should be considered as a trigger for EM. This is especially important to recognize when differentiating between serious dermatological conditions such as EM, SJS, and toxic epidermal necrolysis.