Background Daboia palaestinae is a leading cause of snakebite envenomation in the eastern Mediterranean, with substantial mortality in absence of antivenin. Current recommended antivenin dose is 50 ml; however, antivenin is costly, may be difficult to obtain and is associated with substantial morbidity. Thus, this study was designed to define the minimal effective antivenin dose and identify patients who can be safely treated without antivenin.

Methods This retrospective single-center study was conducted in adults with suspected or confirmed D. palaestinae envenomation. Patients were treated via our previously developed envenomation protocol: no antivenin use for local symptoms and dose scaling for mild or severe systemic symptoms – initially 10 ml antivenin, with repeat dosing for ongoing systemic symptoms. Main outcomes measured were morbidity and mortality associated with this protocol. Secondary outcomes included assessing the demographics and clinical effects of snake envenomation and comparing between those who received antivenin and those who did not.

Results 101 patients were included. 45 minutes [median; interquartile range: 30-61 minutes] elapsed between envenomation and hospital admission, with no differences between groups. Among 52 patients receiving antivenin, 119 [60-237] minutes elapsed between envenomation and initial antivenin administration, with a maximum of 1073 minutes to initial anvenin administration. Maximum until last antivenin was 3860 minutes.

Median antivenin dose was 15 [10-22.5] ml, with 26/52 (50.0%) requiring only 10 ml. 2 patients developed an early antivenin immune reaction, with 1 developing anaphylaxis requiring invasive ventilation. No patients died during hospitalization.

Conclusions This cohort demonstrates that a dose-scaling antivenin protocol can be safely employed, reducing morbidity and costs. This suggests a randomized control trial comparing fixed dose regimen to an escalation protocol and development of similar protocols for envenomations due to other snake species.

The authors have declared no competing interest.

The author(s) received no specific funding for this work.

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The study was approved by the Barzilai University Medical Center institutional review board prior to initiation (approval number: 0009-23-BRZ). Due to the retrospective nature of the study, informed consent was waived.

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All data files are available from the Open Science Foundation database (accession number osf.io/2p685).