An oral add-on for snakebite failed its phase II trial, and how it failed matters
Varespladib, given on top of antivenom in a randomised trial in India and the USA, did not beat placebo. But it reached patients seven hours after the bite, and the authors say that timing may be the story.
Antivenom has a problem that everyone in the field knows and few treatments can fix: it has to go into a vein, in a hospital, under supervision, which is precisely what the rural agricultural populations most exposed to venomous snakes cannot easily reach in time. An oral drug that could be swallowed on the way to care, or given alongside antivenom to blunt the venom faster, has been one of the field's clearest wishes. A new phase II trial tested one such candidate and did not get the answer it hoped for [s1].
The drug is varespladib, a phospholipase A2 inhibitor given intravenously and then orally. Researchers evaluated it as an adjunct to antivenom — not a replacement — in hospitalised patients with snakebite envenoming, in a multicentre, randomised, double-blind, placebo-controlled trial run in India (registration CTRI/2023/10/058782) and the USA (NCT05717062) [s1].
What the trial found
Between 3 June 2023 and 19 October 2024, 140 patients were randomised and 139 were analysed — 73 assigned to varespladib and 66 to placebo, both on top of standard care including antivenom [s1]. The endpoints were split by snake type. For elapid envenoming, the primary endpoint was time to recovery of a five-second head-lift; for viper envenoming, it was the area under the curve to Day 14 of a three-item Snakebite Severity Score [s1].
Neither endpoint separated from placebo. Among elapid-bite patients, mean time to head-lift recovery was 27.6 hours with varespladib versus 36.2 hours with placebo, a difference that did not reach significance (p = 0.6) [s1]. Among viper-bite patients, the severity-score area under the curve to Day 14 was 660 with varespladib versus 629 with placebo (p = 0.7) [s1]. The drug did not meet its primary endpoint [s1].
On safety, the trial was clean: no serious adverse event occurred with varespladib [s1].
Why the authors do not read this as the end
A null trial can mean the drug does not work, or it can mean the drug was not given a chance to work. The authors point squarely at the second possibility, and the timing numbers are why. The study drug was initiated a mean of 7.3 hours after the bite and 3.3 hours after antivenom [s1].
That sequencing matters mechanically. Varespladib targets venom enzymes; antivenom binds and clears venom. Giving the enzyme inhibitor an average of more than three hours after the antivenom is already working means the drug arrived after much of the damage it was meant to interrupt had either been done or was already being neutralised by something else. The trial tested late adjunctive varespladib, and that is the specific thing that failed.
The authors are explicit about a second limitation. Interpretation is constrained by heterogeneity in the snake species responsible for envenoming, and the associated differences in venom composition, clinical manifestations and antivenom treatments [s1]. Pooling elapid and viper bites, across two countries with different snakes and different antivenoms, is a lot of biological variation to ask a 140-patient trial to see through.
The scale of the problem the drug is chasing
The reason a failed phase II trial still counts as news is the size of the gap it was trying to close. Snakebite envenoming causes an estimated 81,000 to 138,000 deaths and more than 400,000 cases of permanent disability each year, disproportionately affecting low-resource regions [s1].
The World Health Organization's figures frame the same burden from the population side: an estimated 5.4 million people are bitten by snakes each year, with 1.8 to 2.7 million cases of envenoming, and around 81,410 to 137,880 deaths annually, alongside roughly three times as many amputations and other permanent disabilities [s2]. The geography is concentrated — in Asia, up to 2 million people are envenomed each year, and in Africa there are an estimated 435,000 to 580,000 bites annually that need treatment [s2].
Against that, WHO's blunt clinical fact is that antivenom remains the frontline answer and that the highest burden falls where health systems are weakest and medical resources sparse [s2]. An oral adjunct that reduced the damage done before a patient reaches antivenom would address exactly that gap — which is why the timing signal in this trial, rather than the negative headline, is the part worth following.
What to watch
The useful next trial is implied by this one's limitations. It would enrol a more homogeneous population — a single envenoming syndrome, ideally a single region's snakes — and, critically, give varespladib earlier relative to the bite rather than hours after antivenom. Whether the drug's developers design that trial, and whether they can run it in the pre-hospital window where an oral agent would actually matter, is the open question this null result leaves behind [s1].
Sources
- Adjunctive Varespladib after antivenom administration for snakebite: A phase II randomized clinical trial, PLOS Neglected Tropical Diseases, 21 September 2026
- Snakebite envenoming (fact sheet), World Health Organization
Sources
- Adjunctive Varespladib after antivenom administration for snakebite: A phase II randomized clinical trial — PLOS Neglected Tropical Diseases , September 21, 2026
- Snakebite envenoming (fact sheet) — World Health Organization
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