Sun10October0740PM 9

You are investigating whether a new antibiotic used in the paediatric population may require dose adjustment in the obese paediatric population.

Which of the following pharmacokinetic parameters would give you the biggest clue as to whether dose adjustment is required?

(Please select 1 option)

Total dose of the drug in milligrams

Half life

T-max

C-max

Volume of distribution Correct

Explanation

Whilst the need for dose adjustment is unlikely, it is volume of distribution which may provide the biggest clue as to whether it is required or not. The definition of volume of distribution is, "The apparent volume in which a drug is distributed immediately after it has been injected intravenously and equilibrated between plasma and the surrounding tissues".

Drugs which have a much larger volume of distribution are ones which are therefore very lipid soluble and undergo rapid re-distribution to tissue after administration. This may be an advantage or disadvantage when it comes to administration of antibiotics, depending on the target tissue. An example of a drug with a low volume of distribution, because it is highly bound to plasma proteins is warfarin. One with a much greater volume of distribution because it is highly lipid soluble is chloroquine.

C-max and T-max are related to drug absorption, and should not be significantly altered by obesity.

Half life is linked to hepatic function if the drug is extensively liver metabolised, and to rate of excretion.

Total dose of the drug in milligrams is largely irrelevant when it comes to the need for dose adjustment.

Answer Statistics

1

1%

2

2%

3

1%

4

6%

5

92%

Times answered: 232