Real-world study on adverse events of central muscle relaxants in the treatment of cervicogenic headache based on the U.S. FAERS database

Background: Central muscle relaxants are widely used in the treatment of cervicogenic headache, which can inhibit the excessive excitation of the central nervous system, relieve neck muscle spasms, and thereby reduce pain and discomfort. However, there is still a lack of real-world studies on the safety of central muscle relaxants. Given the rising incidence of cervicogenic headache in recent years, it is imperative to gain a deeper understanding of the adverse events (AEs) associated with this class of drugs. Methods: The online platform Open Vigil 2.1 was used to query the U.S. Food and Drug Administration's (FDA) Adverse Event Reporting System (FAERS) database for reports on common central muscle relaxants, baclofen and tizanidine. The query spanned from January 1, 2004, to August 31, 2024, and extracted all AEs across all age groups. The Standardized Medical Dictionary for Regulatory Activities (MedDRA) was used to match relevant preferred terms (PTs) and system organ classes (SOCs). The proportional reporting ratio (PRR), reporting odds ratio (ROR), and Bayesian Confidence Propagation Neural Network (BCPNN) methodology were employed to compare the AEs of the two muscle relaxants. Results： There were 14,431 reports with baclofen as the primary suspected drug, with a roughly equal proportion of male and female patients. For tizanidine, there were 365 reports, with more female patients than male. For both drugs, the age group with the highest proportion of patients was 40-59 years old, and the country with the most reports was the United States. Nervous system disorders were the most common SOC category for AEs associated with both drugs. The three most frequently reported AEs for baclofen were withdrawal syndrome, hypersomnia, and pruritus, while the top three AEs for tizanidine were confusional state, dry mouth, and hypotension. Conclusion: The analysis indicates that AEs of both drugs are present in various systemic diseases including nervous system, psychiatric, cardiovascular, respiratory, urinary, and general disorders. However, the incidence and signal strength of these AEs vary depending on the specific drug discussed. In clinical practice, appropriate drugs should be selected based on the specific characteristics of individual patients, and AEs should be monitored.