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DISCUSSION The study highlighted that the potency of the liquid antivenom stored in a sand pot embedded in the ground (pot/ground) with daily watering of the sand is maintained for seven months covering the hottest summer days of the midland. Daily watering of the sand has an advantage over the every third day in keeping the sand temperature 1-2 0 C cooler and it could be carried out routinely at the villages. Enzyme refined antitoxin are more stable than the whole sera preparation and deterioration at temperature between 0 and 5 0 C is negligible (British Pharmacopia, 1969). At 37 0 C the preparation may loose 10-20% of their activity in one year. A slight reduction in neutralizing efficacy to different biological activities observed in our antivenoms could be due to storage of the products at a temperature well above 4 0 C. Liquid antivenom stored at 37 0 C for six months starts to precipitate out indicating loss of efficacy (Christensen, 1975). However, the maximal temperature of the sand recorded in the study is 32 0 C. In order to reach a storage temperature of 37 0 C the shade/room temperature should be 45- 47 0 C that is unlikely, but could not be ruled out especially during summer months in the midland. Even then, the maximal temperature will not last for six months. Although venom neutralizing efficacy of the antivenom in pot/house with daily watering is slightly inferior to pot/ground with daily watering, it could be used if the latter method of storage is not feasible as in our case. It is concluded that liquid antivenom stored in a sand pot embedded in the ground with daily watering should be recommended for storing liquid and lyophilized antivenoms in snakebite endemic areas with no cold storage facility. Moreover it is simple, inexpensive, effective and could be carried out properly in rural villages without much effort. However, practice of rapid turnover of the fresh stock of liquid antivenom especially during the summer months or use of lyophilized preparation should also be encouraged (Tun-Pe et al., 1994). References Potency Assay of the Liquid Russell’s Viper Antivenom Stored at Different Environment British Pharmacopia (1969). The Pharmaceutical Press, London,p.60. Christensen, P A (1975). The stability of refined antivenom. Toxicon, 13:75-77. Laemmli, U S (1970). Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature, London 227:680-685. Theakston, R D G. and Reid, H A (1983). The development of simple standard assay procedures for characterization of snake venoms. Bull. W.H.O,61:949-956. Towbin, H, Staehelin, T & Gordon, J (1979). Electrophoretic transfer of proteins for polyacrylamide gels to nitrocellulose sheets: procedure and some applicants. Proceedings of the National Academy of Science USA,76:4350-4354. Tun-Pe, Aye-Aye-Myint, Than-Win and Daw-Nyein (1994). Potency assay of liquid preparation of enzyme refined monospecific Russell’s viper antivenom. Myanmar Health Sciences Research Journal, 6:56-59. Tun-Pe, Khin-Aye-Kyu, Aye-Aye-Myint, Nu-Nu-Aung, Sann-Mya and Tin-Oo (1998). Clinical significance of early intravenous antivenom in Russell’s viper bite cases in Taungdwingyi district: a preliminary study. Myanmar Health Sciences Research Journal,10:22-25. 85
Management of Snakebite and Research 86 Development of Russell’s Viper Toxoid INTRODUCTION Khin Maung Maung and Win Aung Biochemistry Research Division Department of Medical Research (Lower Myanmar) Abstract Russell’s viper bite is a serious medical problem in Myanmar. Thus active immunization of persons at risk is of utmost importance protective measure. Detoxified venom can be used as effective toxoid for active immunization. Russell’s viper venom (RVV) toxoid was first prepared with 0.5% formalin. In 1986 formalinized toxoid prepared with Sephadex G50 (fine) fractionated RVV were tested on monkeys and human volunteers and found to be safe and immunogenic. In 1980 RVV toxoid was developed by slow and step-wise formalinization method. The appearance of toxicity in formalinized RVV toxoid stored for one year at different temperature was found in 1994. In 1996 stability of Sephadex G75 fractionate RVV was tested at room temperature and found to be stable upto six months. Immunization schedules and age of the toxoid on immunized animals were also studied in 1996. In 1997, it was found that RVV toxoid with 35% sodium bisulfite were stable upto one year at 37°C. RVV toxoid lyophilized and stored at room temperature were found to be less toxic and more immunogenic upto one year. Mice immunized with toxoid prepared by pooling five major enzymes of RVV could not withstand a lethal dose of RVV. Russell’s viper (Daboia russelii siamensis) bite has been a serious medical problem in Myanmar for many decades. Post-bite administration of antivenom, a product of Myanmar Pharmaceutical Factory (MPF), is the only effective and widely used treatment. However, the mortality rate remains considerably high. On many occasions, antivenom treatment is late and irreversible damage of vital organs has already occurred. Also sometimes, the development of lesion is so rapid that the antivenom alone cannot neutralize the lethal effect where large amounts of venom are already introduced into the body. Therefore, development of a suitable and effective measure i.e. active immunization of people susceptible to snakebites is of utmost importance as a protective measure. If the victims are immune to the venom, even to a small degree, the onset of damage is delayed and they can be treated more successfully (WHO, 1981). Therefore, many attempts have been made by various scientists to develop of RVV toxoid for nearly three decades in Myanmar.
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