What is the optimum concentration of m-cresol in antivenoms?

Abstract

Antivenoms against snake and scorpion envenomations are usually equine in nature and composed mostly of F(ab')2; additionally, phenol and m-cresol are mainly employed for their preservation. Although there is no study on this subject, m-cresol is utilized by most manufacturers in a concentration that ranges from 0.15 to 0.35 g%. Decreasing the concentration of m-cresol to its minimal effective level may protect victims from its toxic effects and keep the antivenom stable during its shelf life without forming any aggregates. In the present work, different concentrations of m-cresol, ranging from 0.1 to 0.35 g%, were used with some selected batches of snake and scorpion antivenoms. A low concentration of 0.15 g% showed an acceptable preserving result that complies perfectly with antimicrobial specifications stated by the British Pharmacopoeia. Tested antivenoms (in 12 batches), when kept in a cold room for 39 months (more than their shelf life), retained their physical, chemical and microbiological activities according to the specifications of pharmacopeias. The present data demonstrated that reduction of m-cresol concentration to 0.15 g% in case of equine F(ab')2 antivenoms will improve safety of such preparations and preserve their stability during their shelf life. © CEVAP 2011.