MC test: Pharmaceutical products & drug action

Multiple choice test on D.1 Pharmaceutical products & drug action

Use the following 'quiz' to test your knowledge and understanding of this sub-topic. As this relates to a sub-topic on the options you may need access to the IB data booklet.

If you get an answer wrong, read through the explanation carefully to learn from your mistakes.

Which expression gives the therapeutic index for humans?

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? 

 

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

 

Which statements are correct about the therapeutic index for a specific animal?

I. The therapeutic index = ED50 ÷ LD50

II. ED50 refers to the dose of the drug required to have a noticeable effect on 50% of the specific animal population.

III. LD50 refers to the dose of the drug required to have a lethal effect on 50% of the specific animal population.

The definitions of ED50 and LD50 are correct but the therapeutic index = LD50 ÷ ED50

 

Which best describes therapeutic window?

Ideally the minimum amount of a drug should be used to achieve the desired effect especially when the therapeutic window is small as there is a danger of reaching the minimum toxic dose, i.e. the dose when toxic effects first start.

 

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?

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?

When a drug is administered by intravenous injection all of the drug goes straight into the bloodstream.

 

What is meant by risk-to-benefit ratio?

Risk-to-benefit ratio refers to the side-effects of a drug. For minor problems a low risk-to-benefit should operate but for serious conditions it may be more acceptable to put up with adverse side-effects.

 

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)

The word 'drug' (or medicine) can have different meanings in different societies but generally a drug is a substance that will have one or more of the above effects.  

 

Which factors explain why all the isomers of a promising drug should be tested during clinical trials.

I. One or more of the isomers of the effective drug may no clinical effect.

II. One or more of the isomers of the effective drug may be toxic.

III. One or more of the isomers of the effective drug may have an adverse clinical effect.

Sometimes isomers are completely ineffective, e.g. cis-platin is a good anti-cancer drug whereas trans-platin has no effect (this is because it has the wrong stereochemistry to bond with the target receptor site). Sometimes isomers can cause adverse side effects and in some cases (e.g. thalidomide) severe foetal abnormalities may occur.

 

Which term best describes the phenomenon that leads to physical withdrawal symptoms when reducing or stopping the dosage of a drug?

Habituation involves psychological dependence on the drug but reduction or removal of the drug does not cause physical withdrawal symptoms.

 

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