Lorke's method of determination of oral acute toxicity(LD50) of a suspected toxic substance is divided into two phases, Phase I & Phase II . I understood that you can proceed to phase II if there is no death of the animals having administered 10mg/kg ,100mg/kg & 1000mg/kg respectively in Phase I.The phase II is expected to have 2000mg/kg, 3000mg/kg,4000mg/kg and 5000mg/kg respectively.
My challenge is: i administered 10mg/kg,100mg/kg &1000mg/kg in phase I. No death was recorded in 10mg/kg & 100mg/kg but 1000mg/kg of the suspected substance recorded death.
Therefore the LD50 will be geometric mean of 100x1000=316mg/kg......................................LD50 (1)
However, i found out that if i vary the doses at 250mg/kg, 450mg/kg , 650mg/kg & 850mg/kg respectively that the LD50 will also change.In this variation, death occurred at 450mg/kg, 650mg/kg and 850mg/kg respectively while no death occurred at 250mg/kg.
Therefore, LD50 will be geometric mean of :
250 x 450=335mg/kg ..............................................LD50(2)
I need your input on what to do.Which of the LD50 is the best?
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