Dose versus survival time curves in the evaluation of ‘prompt’ and ‘delayed’ acute toxicities

The acute toxicity of arecoline, diisopropylfluorophosphate, nicotine and pilocarpine alone or in association with atropine has been evaluated from percentage lethality and from the linear correlation of (doses/(survival time)) vs doses. The experimental points obtained with arecoline and diisopropylfluorophosphate, alone or in association with atropine 50 mg kg⁻¹, are apparently ordered according to two straight lines. That at lower doses gave the LD50 values of the compounds studied. The values found are comparable to those found with percentage lethality. The straight line found at high doses may indicate that over certain doses the drugs kill by a different mechanism. It is concluded that the evaluation of the survival time may be a reliable method in identifying and in evaluating quantitatively the two forms of toxicity.