Content deleted Content added
m {{LD50}} |
No edit summary |
||
Line 9:
{{pharma-stub}}
'''Protective Index'''
Protective index refers to the factor by which the
dose of a toxicant must be multiplied to produce a
defined level of toxicity in the presence of a nontoxic
dose of another chemical<sup><sup>Superscript text</sup><sup>Superscript text</sup></sup>.
''Protective index = LD50 of A with B/LD50 of A alone''
The higher the protective index , better is the
antidotal value of a given substance. Sometimes the
protective index is higher in the presence of two or
more substances than in the presence of either of the
substances alone. For example, the LD50 of potassium
cyanide alone is 11 mg/kg, whereas it is 21 mg/kg
in the presence of sodium nitrite, giving a protective
index of 1.91. The LD50 of potassium cyanide in the
presence of sodium thiosulfate is 35 mg/kg, giving
a protective index of 3.2. The LD50 of potassium
cyanide in the presence of both nitrite and thiosulfate
is 52 mg/kg with a protective index of 4.73 (Way
et al. 1972). Since the protective index is higher for
the simultaneous use of nitrite and thiosulfate, the
two chemicals constitute the antidote against cyanide
intoxication.
| |||