Sri Lanka Journal of Medicine Vol. 26 No.2, 2017 54 T REVIEW ARTICLES PHARMACODYNAMICS AND PHARMACOKINETICS OF SNAKE ANTIVENOM Bhagya Nikapitiya, Kalana Maduwage Department of Biochemistry, Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka Corresponding Author: Dr. Kalana Maduwage Tel: +94 7 1414 5738 E.mail: kalanapm@gmail.com https://orcid.org/0000-0001-5351-808X Abstract Intact or fractionated immunoglobulins are used as snake antivenom to treat snake envenomation. Intravenously administered antivenom binds with snake toxins in the circulation and neutralizes the toxins. Binding of antivenom to venom in the central compartment prevents the distribution of venom to the peripheral tissues and enhances the elimination of venom. Reduction of antivenom concentration in the central compartment is due to both distribution to the peripheral tissues and elimination. Pharmacokinetics of snake antivenom varies among the three different types of immunoglobulins, namely whole IgG, F(ab’) 2 and Fab. Pharmacokinetics of F(ab’) 2 antivenom is best described by two compartment model with zero order input and linear elimination kinetics. Fab and F(ab’) 2 antivenom with smaller molecular masses have a larger volume of distribution than whole IgG antivenom. A biphasic decline of intravenously administered whole IgG and F(ab’) 2 antivenom has been observed. Key words: snake antivenom, pharmacodynamics, pharmacokinetics, venom, toxins Snake envenomation Snake envenomation is a neglected tropical disease resulting from venom injected by a venomous snake into human. Snakebites usually occur under accidental circumstances, hence are described as an accidental animal attack. Venom is a highly complex toxic secretion produced at the venom glands of venomous snakes 1 . Venom is injected into human through specifically evolved teeth known as fangs which are connected to the venom gland by a duct system 2 . Snake venom is injected into human commonly by subcutaneous, or deep intramuscular routes, and rarely via direct the intravenous route 1,2 . The composition of snake venom is highly complex and diverse 1 . As a result of its complexity, a wide range of clinical manifestations are evident in snake envenomation, due to the alteration of routine physiology and biochemistry 1,2 . Some types of snake venom initiates various clinical effects at the site of the bite, varying from local pain, swelling, blistering and local tissue necrosis, which may results in amputations 3 . Others produce systemic effects of snake venom including coagulopathy, neurotoxicity, Received: 30/03/2018 Accepted revised version: 09/06/2018 Published: 29/06/2018 DOI: http://doi.org/10.4038/sljm.v27i1.79 This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY-4.0)