How does liver failure affect the pharmacology of drugs?

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College Answer

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.