(Kiosk 2) Terbinafine-induced Myopathy: A Case Report

Case Diagnosis: 76 year old male with chronic bacterial and fungal sinusitis who presented with acute Terbinafine-related myopathy.

Case Description or Program Description: The patient was initially referred to PM&R for evaluation of chronic back pain, but at the time of initial evaluation, he noted that he had been having 1 week of progressively worsening, diffuse muscle soreness and fatiguability. His past medical history was significant for chronic, recurrent bacterial and fungal sinusitis for which he was followed by physicians from Infectious Disease and Otolaryngology. The patient had recently had positive nasal cultures for Paecilomyces species, and three weeks prior was started on Terbinafine, a medication he had not previously used before. Initial physical examination was only remarkable for tenderness to palpation over several muscles of bilateral upper and lower extremities. Serum creatinine kinase (CK) was ordered and though levels were 175 Units/Liter and within normal limits, there was an acute increase from the patient's previous baseline of 85 Units/Liter since starting Terbinafine. The presumptive diagnosis of medication-induced myopathy was made, but based on the results of the patient's fungal culture and resistance to other antifungal drugs, it was advised that the patient complete six more weeks of Terbinafine, after which time Terbinafine was discontinued.

Setting: Sports Medicine Clinic

Assessment/Results: After Terbinafine was discontinued, the patient had marked improvement, with strength returning and myalgias resolving within 1 week. The diagnosis of Terbinafine-associated myopathy seemed to have been confirmed in our patient by improvement of symptoms with cessation of medication in the absence of other changes.

Discussion (relevance): To our knowledge, there are a very limited number of cases reporting an association between Terbinafine and drug-induced muscle disorders, the majority of which report rhabdomyolysis as a primary diagnosis. Terbinafine-induced myopathy marked by myalgias and relative increases in CK is unusual.

Conclusions: Terbinafine should be considered as a medication that can induce myopathy.