AsianScientist (May 10, 2011) – Anti-venoms used in the treatment of bites by a poisonous snake have the potential to cause life-threatening allergic reactions. These reactions are usually treated with adrenaline, the mainstay of treatment, promethazine (an antihistamine), and steroids such as hydrocortisone.
A study recently published in the Public Library of Science has demonstrated that giving low-dose adrenaline is safe and reduces the risk of acute severe reactions to the treatment, but giving promethazine has no such effect and giving hydrocortisone may actually be harmful.
Researchers from the Clinical Trials Unit at the University of Kelaniya in Ragama, Sri Lanka say these findings are important because in some countries where snake bites are a major health problem, acute allergic reactions to poor quality anti-venoms are common and often fatal.
The double-blinded study involved more than 1,000 people who were admitted to five hospitals in Sri Lanka after experiencing a snakebite. Patients were randomized to receive low-dose adrenaline, promethazine, hydrocortisone or placebo — alone and in all possible combinations — immediately before treatment with an anti-venom infusion.
Compared with placebo, pretreatment with adrenaline reduced severe reactions to the anti-venom by 43 percent at one hour and by 38 percent over 48 hours. By contrast, neither hydrocortisone nor promethazine given alone reduced the rate of adverse reactions to the anti-venom and adding hydrocortisone appeared to negate the beneficial effect of adrenaline.
These findings also emphasize the high rate of acute adverse reactions to anti-venom and stress the importance of improving the quality of the available anti-venoms in Sri Lanka and South Asia.
“The need for concerted action by local health and regulatory authorities, the World Health Organization, and other stakeholders, including technology transfer programs between anti-venom manufacturers, to improve the quality of anti-venom can not be overemphasized,” said the authors.
The article can be found at: de Silva HA et al. (2011) Low-Dose Adrenaline, Promethazine, and Hydrocortisone in the Prevention of Acute Adverse Reactions to Antivenom following Snakebite: A Randomised, Double-Blind, Placebo-Controlled Trial.
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Source: Public Library of Science.
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