ABCP Review - Basic Science: Pharmacology QUESTIONS WITH 100% CORRECT ANSWERS 2023

ABCP Review - Basic Science: Pharmacology QUESTIONS WITH 100% CORRECT ANSWERS 2023 Differentiate pharmacokinetics from pharmacodynamics. - ANSWER Pharmacodynamics is the study of what the drug does to the body - Governs the concentration-effect part of the interaction Pharmacokinetics is what the body does to the drug - Governs the dosage-concentration part of the interaction What factors influence the extent of pharmacokinetic absorption? - ANSWER Strongly influenced by chemical solubility of the drug compound Route of administration Physiochemical properties of the drug Surface area available for absorption What happens with pharmacokinetic distribution? - ANSWER Occurs after absorption into blood stream Agents may be modified during distribution - Biotransformed or inactivated - Excreted without chemical change - Distributed to non-target areas - Bind to plasma proteins Define the first pass effect. - ANSWER Metabolism of a drug and its passage from the liver into the circulation Drug given orally may be extensively metabolized by the liver before reaching the systemic circulation (high first-pass effect) Same drug given IV bypasses the liver, preventing the first-pass effect from taking place, and more drug reaches the circulation Describe pharmacokinetic elimination. - ANSWER Excretion/clearance Terminates drug effect Most often via the kidney - Renal function impairment could prolong drug action or promote drug toxicity Can occur via other routes - Inhalation agents via the lungs - Skin via sweat - Bowels What are some effects of hypothermia on drug action? - ANSWER Hypothermia slows metabolism of drugs Clearance of drugs has been shown to be reduced - Propofol - Fentanyl - Morphine - Midazolam - Rocuronium - Vecuronium What are some effects of hemodilution on drug concentration? - ANSWER Hemodilution occurring at institution of CPB decreases circulating drug concentration Eventual plasma concentration of drug depends on: - Plasma protein binding - Original volume of distribution - Extent of equilibration between tissue and plasma at time of institution of CPB What are the effects of hemoconcentration on drug concentrations? - ANSWER Main determinant of passage through the hemofilter membrane is molecular weight Most drugs used on CPB have MW well below the pore size of 55-65kDa THEREFORE most essential factor to consider is percentage of that drug that is bound to plasma proteins Give the pharmacology definition of "drug". - ANSWER Defined as a substance that brings about a change in biological function through its chemical action Give the pharmacology definition of "receptor". - ANSWER A specific molecule that the drug may interact with that plays a regulatory role. What factors influence drug-receptor relations? - ANSWER The ability of a drug to bind to its receptor is mediated by the chemical structure of the drug that allows it to interact with the surface or receptor In order to interact with its receptor, a drug must have the appropriate - Size - Electric charge - Shape - Atomic composition