Protective effects of clinical anticholinergic and anticholinesterase agents against Bungarus multicinctus venom and neurotoxin-rich snake venoms

Bungarus multicinctus is one of the most venomous and lethal snake species in mainland China, with envenomation resulting in a mortality rate as high as 23%. Currently, antivenin against B. multicinctus remains the gold standard for treating bites from this species. However, in remote mountainous areas or rural regions of China, access to antivenin may be delayed or unavailable following a bite. The lethal components of B. multicinctus venom include α-, β-, γ- and κ-bungarotoxins, which act on either the presynaptic or postsynaptic membrane, thereby altering acetylcholine levels in the synaptic cleft. This study aims to evaluate pharmaceutical agents that confer prophylactic or protective effects against bungarotoxins and neurotoxin-rich snake venoms. Based on theoretical considerations, we postulate that certain anticholinergic or anticholinesterase agents may exhibit potential protective efficacy against these venom components. This study investigated the protective effects of clinically standard anticholinergic and anticholinesterase agents-scopolamine, neostigmine methylsulfate, bethanechol chloride, pilocarpine hydrochloride, and atropine sulfate-against different bungarotoxins and wide distribution neurotoxin-rich crude snake venoms (B. multicinctus, Naja atra and Ophiophagus hannah). Our results showed that neostigmine methylsulfate and atropine sulfate exerted significant protective effects (P < 0.01) against three-finger toxins contained in B. multicinctus venom, including α-bungarotoxin, γ-bungarotoxin, α-bungarotoxin+γ-bungarotoxin combinations, β-bungarotoxin+α-bungarotoxin combinations, and β-bungarotoxin+γ-bungarotoxin combinations. In mice animal models treated with B. multicinctus antivenin, neostigmine methylsulfate and atropine sulfate retained profound protective effects (P < 0.01) against β-bungarotoxin+α-bungarotoxin and β-bungarotoxin+γ-bungarotoxin mixtures. However, these clinic-used drugs showed no significant protective effect against B. multicinctus crude venom, with only modest survival time prolongation without statistical significance observed. Under the same conditions, theses drugs showed no effects on king cobra venoms and significantly prompted the death of the tested animals. Present investigation provides a scientific basis for the treatment of B. multicinctus bites in remote mountainous areas or rural regions of southern China. Upon confirming victims were bitten by B. multicinctus, administering atropine sulfate or neostigmine methylsulfate as emergency treatment might provide supplementary benefits for subsequent care. Importantly, the administration of clinic used drugs does not interfere with the efficacy of B. multicinctus antivenin in later treating stages.