D.1 Pharmaceutical products & drug action

Which expression gives the therapeutic index for humans?

• LD₅₀ ÷ ED₅₀

• ED₅₀ ÷ LD₅₀

• TD₅₀ ÷ ED₅₀

• ED₅₀ ÷ TD₅₀

Answer explanation

The therapeutic index relates the risks involved in taking the drug to the benefits it gives. In humans this is equal to TD₅₀ ÷ ED₅₀.

What does the T stand for in the term TD₅₀? 

• Therapeutic

• Tolerance

• Toxic

• Target

Answer explanation

The toxic dose₅₀ is the dose that causes a toxic effect in 50% of the human population.

This statement is about the therapeutic index for a specific animal: The therapeutic index = ED₅₀ ÷ LD₅₀

• True

• False

This statement is about the therapeutic index for a specific animal: ED₅₀ refers to the dose of the drug required to have a noticeable effect on 50% of the specific animal population.

• True

• False

This statement is about the therapeutic index for a specific animal: LD₅₀ refers to the dose of the drug required to have a lethal effect on 50% of the specific animal population.

• True

• False

Which best describes therapeutic window?

• The difference between the dosage required for the ED₅₀ and the dosage required for the LD₅₀.

• The difference between the dosage required for the ED₅₀ and the dosage required for the TD₅₀.

• The range of dosage between the minimum amount of drug required to have the desired effect and a medically unacceptable adverse effect.

Which best describes the need of repeated users of heroin to take greater and greater amounts of heroin in order to achieve the same level of response as the first time they used it?

• Dependence

• Tolerance

• Addiction

• Habituation

Answer explanation

Tolerance describes the progressive reduction in the effect of a drug following repeated exposure to it ,so that it no longer has the desired effect as the original dose. The danger is that in order to achieve the initial effect the user may take a lethal amount of the drug.

Which method of administering drugs has a bioavailability of 100% by definition?

• oral

• intramuscular injection

• intravenous injection

• inhalation

What is meant by risk-to-benefit ratio?

• a comparison of the severity of the side-effects of a drug compared to its effectiveness

• a comparison of the danger of becoming tolerant of a drug compared to its effectiveness

• a comparison of the danger of becoming addicted to a drug compared to its effectiveness

Which are properties of some or all substances classed as drugs?

I. can alter mood or emotions

II. can alter incoming sensory perceptions

III. can alter the physiological state (including consciousness, activity level and/or coordination)

• II and III only

• I and II only

• I and III only

• I, II and III