Ch3 POPULATION LEVEL: THERAPEUTIC INDEX

Question 1

Quantal

Answer 1

There are only two possible responses - does the drug have an effect? yes or no

Question 2

dose response curve

Answer 2

a logarithmic expression used to determine the effective dose at which 50% of the population will respond to a drug.

x axis - log of drug dose
y axis - % of cumulative biological response

Question 3

ED50

Answer 3

the effective dose required to treat 50% of the population

Question 4

LD50

Answer 4

The lethal dose for 50% of the population

Question 5

Therapeutic Window

Answer 5

the difference between the dose of drug that is effective and the dose that causes unacceptable side effects. The difference between the ED50 and the LD50

Question 6

narrow therapeutic window

Answer 6

are typically the drugs that are used to treat serious ailments. Clinicians have to start with a very low dose of these very toxic drugs and slowly increase the dose while monitoring their patients very carefully.

Question 7

wide therapeutic window

Answer 7

a lot of difference between the effective dose and the toxic dose (or, in this case, the lethal dose). In other words, the dose given could be increased a lot before it would become dangerous to the patient.

Question 8

Therapeutic Index

Answer 8

is calculated by dividing the lethal dose (LD50) by the effective dose (ED50)

A drug with a small therapeutic index is also called NTI (for “narrow therapeutic index”), which means the drug has only a narrow window in which the therapeutic effect outweighs the negative side effects.