How does liver failure affect the pharmacology of drugs?
Good answers were structured using pharmacokinetic and pharmacodynamics headings.
They included some mention of changes in absorption, volume of distribution (an increase
in Vd in liver failure), altered protein binding, altered metabolism and thus change in
clearance, and changes in excretion (decreased biliary excretion of drugs). In respect to
pharmacodynamics candidates could have mentioned increased sensitivity and prolonged
action of sedative drugs, oral anticoagulants, etc. Good candidates also differentiated for
acute (often hepatocellular dysfunction) and chronic liver failure (cirrhosis and changes in
liver blood flow). Common problems were not using a logical structure to answer the
question and stating an effect but not describing how this affected pharmacology. For
example stating decreased albumin production but then not stating the consequence of this
on drug distribution. Primary examination questions may often require candidatesto
integrate knowledge from across different sections of the syllabusor apply basic
physiological or pharmacological principles.