Antivenom therapy is the only effective treatment for snake
envenomation. Monovalent antivenoms are raised with venom
from one particular species and hence generally only effective in
the treatment of envenomation caused by the particular species.
Because of the difficulties in accurate diagnosis of the biting
species, polyvalent antivenoms that offer paraspecific protection
against several venomous snake bites have also been developed
and become commercially available. It has been argued that
monovalent antivenoms are generally more effective than polyvalent
antivenoms, though this has not been firmly established. At
present, several types of polyvalent antivenoms against Afro-Asian
venomous snakes are available in the market, produced mainly by
Asian or African commercial pharmaceutical firms or government
institutions [5,6]. There is, however, a lack of rigorous evaluation
of the paraspecific protective actions of these commercially
available polyvalent antivenoms. Recently, Thai Red Cross
Society produced a new polyvalent antivenom that offersprotection against neurotoxic envenomations by elapids in Thailand.
This polyvalent antivenom, termed Neuro Polyvalent Snake
Antivenom (abbreviated as NPAV) is raised against venoms of four
medically important cobras and kraits in Thailand, i.e. Naja
kaouthia (Thai monocellate cobra), Ophiophagus hannah (king cobra),
Bungarus candidus (Malayan krait) and Bungarus fasciatus (banded
krait). In this paper, we report evaluation of the cross-neutralizing
potential of NPAV against heterologous venoms of common Afro-
Asian cobras (Naja spp. and Ophiophagus hannah) and Asian kraits
(Bungarus spp.) We also compared the efficacy of the polyvalent
antivenom versus the relevant monovalent antivenom. The results
will provide preliminary information as to whether the polyvalent
antivenom could find therapeutic application for cobra and krait
envenomations outside of Thailand, as well as contribute to the
design of a broad-spectrum, Pan-Asian polyvalent antivenom [7].