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2013-10-06 02:17:20
pharm tox

Pharmacodynamics in pharm and tox
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  1. pharmacodynamics
    study of the mechanisms by which drugs produce changes in the physiological functions in the body
  2. 4 ways drugs work
    • interact with specific receptors
    • alter activity of enzymes
    • binding to ion channels or transport proteins
    • act by nonspecific physical or chemical interactions
  3. where most receptors are located
    outside surface of the cell membrane
  4. How most drugs exert their effects
    interaction with specific drug receptors, leading to a change in the physiological function
  5. drug receptor
    • usually a protein macromolecule produced by the body
    • interacts with endogenous substance, will also interact with drug molecule with similar size, charge, shape and atomic composition
  6. endogenous substance
    a substance produced by the body
  7. exogenous substance
    a substance that is not produced by the body
  8. ligand
    molecule that binds to the receptor
  9. ligand neurotransmitter at neuromuscular junction
  10. agonist
    • drug that occupies and activates a receptor, thereby producing a cellular response
    • affinity for receptor, efficacy at receptor, briefly occupies receptor
  11. intrinsic activity
  12. antagonist
    • a drug that occupies a receptor but does not activate the receptor
    • affinity without efficacy.  Occupies the space normally occupied by agonist/endogenous ligand.
  13. two types of antagonists
    • Competitive/reversible (briefly occupy receptors, can be overcome)
    • irreversible antagonists (permanently occupy, often covalent, to their receptors)
  14. competitive/reversible antagonist
    briefly occupy receptors can be overcome with enough ligand.
  15. irreversible antagonists
    permanently, often covalently, bind to their receptors
  16. Graded dose response curve
    dose vs. response
  17. Threshold dose
    dose that produces an observable effect.
  18. Ceiling effect
    plateau of curve indicating that further increase in dose will not increase response (maximal efficacy of drug)
  19. Drug efficacy
    the magnitude of the maximal response that can be elicited by a drug
  20. Drug potency
    a measure of the quantity of drug required to obtain a particular response
  21. quantal dose response curve
    population v. drug
  22. ED50 Median effective dose
    in quantal dose response curve, the dose of a drug that produces a specified, desired effect in 50% of the animal population tested
  23. TD50 Median toxic dose
    • The dose of drug which produces a specified toxic effect in 50% of the population tested
    • Not death, can be treatable
  24. Therapeutic Index (TI)50
    • TI = TD50/ED50
    • The ratio.  A really high TI is safe, lower is worse (bad effect/good effect)
  25. LD50 Medial Lethal Dose
    the dose of drug that causes death in 50% of the animal population tested
  26. partial agonist
    same effect at effective dose, much lower max efficacy.  Cannot elicit a maximal response compared to a full agonist
  27. Adverse drug reaction
    harmful or undesirable effect of a drug
  28. mechanism-based adverse drug reaction
    a harmful or undesirable effect of a drug that is a PREDICTABLE extension of the principal pharmacological actions of the drug
  29. Idiosyncratic adverse drug reaction
    a reaction to a drug that is particular to a specific patient, due to interactions of the drug with unique hose factors that are unrelated to the principal actions of the drug.
  30. side effect
    any effect of a drug other than the one for which it is being used
  31. drug interactions
    • a change in the pharmacological response of a drug due to the presence of a second drug
    • Object drug is the drug acted upon
    • precipitant drug influences other.
  32. Pharmacokinetic drug interactions
    plasma or tissue levels are altered by the presence of another drug, causes changes in absorption, distribution, metabolism and/or elimination.
  33. pharmacodynamic drug interaction
    • action or effect of drug is altered by another drug.  Occurs at site of drug action.  
    • Include antagonistic (reversals), additive (2 drugs with same effect, seratonin syndrome) and synergistic (precip enhances effect of objecive, P450 blocker with cyclosporine b/c cyclo is so expensive, can use less)
  34. pharmaceutic drug interactions
    The resulting physical or chemical reactions that take place as a result of mixing drugs in a container or syringe.