27th National Clinical Education Symposium Presentation Abstracts
28 APRIL 2025, MONDAY
13:00-14:00 POSTER PRESENTATION SESSION-1
A Case Study: Myositis Due To Clozapine Use
Mehmet Eren Yaşaran1, Soner Akar1, Cansu Bak1, Aslıhan Özdemir Yaşaran1, Figen Ünal Demir1
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1. Department of Psychiatry, Tokat Gaziosmanpaşa University, Tokat, Turkey
DOI: 10.5080/kes27.abs111 Page 137
OBJECTIVE:Myositis is a chronic inflammation of the skeletal muscle, leading to muscle weakness. Clozapine-induced myositis is a rare side effect reported in the literature. We present a schizoaffective disorder patient followed-up for 19 years, who has used clozapine for one year. After reporting lower extremity weakness, elevated creatine kinase (CK) levels led to a neurology consultation. Upon myositis diagnosis, this rare side effect was documented to contribute to the literature. CASE (The patient consent must be provided and specified with appropriate terms.):The patient was a 53-year-old male with schizoaffective disorder for the past 19 years. His initial symptoms included apathy, lack of motivation, and fear of harm, with psychotic episodes. He had multiple depressive episodes requiring hospitalization. Despite treatment with various psychotropics, he showed only partial improvement. In February 2024, clozapine was initiated and increased to 200 mg/day, leading to functional improvement and reduced depressive symptoms. In November 2024, he reported leg weakness. Blood tests revealed CK: 1939 U/L, CK-MB: 62.08 U/L, C-reactive protein: 5.03 mg/L, alanine aminotransferase: 77.5 U/L, and aspartate aminotransferase: 97.8 U/L. Recent infections, cardiac pathologies, and acute conditions like neuroleptic malignant syndrome were excluded. Neurology consultation and electromyography found no alternative cause for the myositis. The clozapine was gradually tapered and transitioned to olanzapine. CK levels were monitored: ? 200 mg/day: CK 1939 U/L ? 150 mg/day: CK 1847 U/L ? 100 mg/day: CK 1193 U/L ? One month after discontinuation: CK 248 U/L (within normal range) Written informed consent was obtained from the patient and his relatives for the case report. DISCUSSION:To confirm clozapine-induced myositis, other causes must be excluded. As a dose-independent effect, CK normalization after discontinuation strongly supports a drug-induced etiology. Though rare, clinicians should consider myositis in clozapine-treated patients with musculoskeletal symptoms.