Comparative therapeutic index, lethal time and safety margin of various toxicants and snake antivenoms using newly...

The assessment of clinical efficacy and toxicity is very important in pharmacology and toxicology. The effects of psychostimulants (e.g. amphetamine), psychotomimetics (e.g. Cannabis sativus) and snake antivenoms are sometimes unpredictable even at lower doses, leading to serious intoxication and fatal consequences. Hence, there is need to re-assess some formulas for calculation of therapeutic index, lethal time and safety margin with a view to identifying therapeutic agents with remarkable toxicity potentials.

The therapeutic index formula [Formula: see text] was derived from T₁ = LD₅₀/ED₅₀ and ED₅₀ = [Formula: see text]. Findings have shown that, therapeutic index is a function of death reversal (s), safety factor (10^-4) and weight of animal (Wa). However, the new safety margin formula [Formula: see text] derived from LT₅₀ = [Formula: see text] and MS = [Formula: see text] shows that safety margin is a function of cube root of ratio between LT₅₀ and LD₅₀ and ED_100th. Concentration (k) of toxicant at the receptor [Formula: see text] derived from D₁ × Tⁿ = K and LD₁ = [Formula: see text] shows that therapeutic index, lethal time and safety margin is a function of drug or toxicant concentration at the receptor, the drug-receptor interaction and dose of toxicant or drug administered at a particular time.