Abstract: Objective To analyze the characteristics and related risk factors of adverse drug reactions (ADR) associated with Haemocoagulase Agkistrodon for injection, and to provide evidence for safe clinical use. Methods ADR reports submitted between January 1, 2011 and December 31, 2024, from a certain province, involving Haemocoagulase Agkistrodon as the suspected drug, were collected. Data on patients’ demographics, medication use, ADR occurrence, and clinical outcomes were extracted and analyzed to characterize the features of these ADR. Results Among the 209 ADR reports, the occurrence of serious ADR showed no statistically significant association with off-label use (P>0.05). However, statistically significant differences were observed with respect to age, concomitant medication use, indication for administration, and route of administration (P<0.05). Most ADR occurred within 30 minutes after administration (56.93%), and serious ADR were predominantly concentrated within this period (77.42%), exhibiting characteristics of immediate hypersensitivity reactions, primarily manifesting as anaphylactic shock. ADR involved multiple organ systems, mainly affecting the skin and subcutaneous tissue as well as the gastrointestinal system. A total of 99.04% of the ADR either resolved or showed improvement. Conclusion Adverse reactions associated with Haemocoagulase Agkistrodon for Injection exhibit distinct immediate-onset characteristics and are related to the route of administration. Clinical medication should focus on rigorous monitoring within 30 minutes following administration. Preparedness for emergency rescue measures in response to hypersensitivity reactions is essential.

Key words: Haemocoagulase Agkistrodon, Immediate Hypersensitivity Reaction, Skin, Subcutaneous Tissue, Gastrointestinal System, Adverse Drug Reaction (ADR), Safety