Question 11

Outline the influence of pregnancy upon drug pharmacokinetics

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College Answer

Answers framed around the structure of absorption, distribution, metabolism and
excretion performed better. An approach based on the physiologic changes of
pregnancy performed less well because important areas of pharmacokinetics were
omitted. The effects of pregnancy on oral absorption should have included a
discussion of gastrointestinal motility, nausea and vomiting and gut blood flow.
Absorption from sites other than the gastrointestinal tract, such as skin, lung and the
epidural space and the effect of pregnancy on these should have been mentioned.
Many answers were vague on the effects of increases in total body water and
plasma volume and cardiac output and changes in plasma protein binding on the
distribution of drugs. Most answers did not provide enough specific examples. The
effect of pregnancy hormones on liver enzyme activity were mentioned by few.
Syllabus: Generic Pharmacology III 2d
Recommended sources: Foundations of Anaesthesia: Basic clinical Science.
Hemmings and Hopkins, and Anaesthesia, Miller.