Question

Drug X is normally administered in 25mg tablets and some patients need 3 tablets to feel a therapeutic effect. The drug was reformulated and named drug Z and several patients died after taking just one 25mg tablet. If 50% of of the users of drug z died after taking one tablet which of the following statements is correct?

	a.) The LD50 for drug Z is 25mg
	b.) The TD50 for drug Z is 75mg
	c. )The therapeutic index of drug Z is larger than that of drug X
	d.) The ED50 for drug Z is 25mg
	e.) Drug X is more potent than drug Z

Answer 1

Let's first understand the definitions:

LD50: LD50 is the lethal dose for 50% of the total population. When with a particular dose of a drug if 50% of subjects survived then the does is called as LD50.

TD50: toxicity dose: The dose at which 50% of the total population experiences defined toxicity is called as TD50. But here toxicity is not defined, hence we can not call the value as TD50 so option b is not the answer.

The therapeutic index is the ratio of the dose that produces toxicity to the dose that produces a clinically desired or effective response in a population of individuals. But here we do not know the toxicity of effectiveness of the any of formulation X or Z. Hence, option c is not the answer.

ED50: drug dose that produces the desired response in half the population. But here we are not talking about any effective dosage. Hence option d is not the answer.

Potent: potency of a drug is a measure of drug activity expressed in terms of the amount required to produce an effect of given intensity. Here we do not have any information on the effectiveness of the drug. Hence option e is not the answer.

Thus the answer is the option a.) The LD50 for drug Z is 25mg