Exam 3

  1. What is the interaction b/w mag stearate and ketoprofen?
    • mag stearate increases decomposition of ketoprofen during tablet making process
    • efficacy of ketoprofen is decreased or completely abolished
  2. What is the interaction b/w phenobarb and PEG 4000?
    • PEG 4000 prolongs the onset of action of phenobarb
    • longer transit time= more potential drug interactions
  3. What is the interaction b/w phenytoin and D5W?
    • crystal formation
    • decreased concentration of phenytoin by degrading the pH of it
  4. What is the interaction b/w blood and PEG 300?
    the PEG 300 can cause hemolysis
  5. What is the interaction b/w tetracyclines and antacids?
    antacids chelate tetracycline, decreasin its concentration and leading to treatment failure
  6. What is the interaction b/w pomegranate juice and warfarin?
    pomegranate juice can inhibit P450 enzymes that metabolize warfarin (esp 2C9) so increased bleeding
  7. What is the interaction b/w atorvastatin and niacin?
    additive synergistic effects = rhabdomyolysis and myopathy
  8. What is the interaction b/w omeprazole and atorvastatin?
    • they both inhibit CYP enzymes
    • competitive inhibition leads to increased levels of one or the other
    • rhabdomyolysis
  9. What is the interaction b/w warfarin and phenytoin?
    • both bind to proteins, but phenytoin has a higher affinity for blood proteins, so it displaces warfarin
    • more free warfarin= higher concentration of warfarin initially
    • both are metabolized by 2C9, so after some time, b/c warfarin is more extensively metabolized by 2C9 than phenytoin, warfarin concentrations will be decreased = blood clots
  10. What is the interaction b/w clopidegrel (plavix) and warfarin?
    both are antiplatelet drugs= increased bleeding time
  11. What is the interaction b/w grapefruit juice and nifedipine?
    grapefruit inhibits intestinal CYP enzymes that metabolize nifedipine= more nifedipine available and greater decrease in blood pressure
  12. What is the interaction b/w spironolactone and potassium?
    since sprironolactone is potassium sparing diuretic, adding potassium to diet can increase levels to hyperkalemia
  13. Drug Clearance/Inulin Clearance<1 = ?
    drug is partially absorbed
  14. Drug Clearance/Inulin Clearance=1 = ?
    drug is filtered only
  15. Drug Clearance/Inulin Clearance>1 = ?
    drug is actively secreted
  16. What is fr?
    reabsorption fraction
  17. What is fe?
    drug excreted unchanged
  18. How do we calculate total body clearance after an IV infusion?
    ClT = R/Css
  19. What is the def of drug clearance?
  20. ______ considers the entire body as a single drug-eliminating system?
  21. T/F: Total drug clearance identifies the mechanism of the process
  22. T/F: ClT is a constant
    true (in an ideal situation)
  23. What is renal clearance, lung clearance, and hepatic clearance?
    • renal: keVD
    • lung: klVD
    • hepatic: kmVD
  24. How do we find the extraction ratio ER?
    Ca - Cv / Ca
  25. How do we find clearance when we know blood flow and ER?
    Cl = QER
  26. Which value has no units?
  27. Where do the values fall for an ER answer?
    between 0 and 1
  28. What is Q?
    blood flow
  29. What two things does physiological clearance depend on?
    • blood flow
    • ER
  30. What does a high ER do to bioavailability?
    Higher ER= lower oral bioavailability
  31. What is Ca?
    blood flow entering the liver (arterial)
  32. What is Cv?
    blood flow leaving the liver (venous)
  33. How do we find hepatic clearance when we know total body clearance and we may/may not know the renal clearance?
    Clh = ClT - ClR
  34. How do we find hepatic clearance when we know total body clearance and how much drug is excreted intact and how much is excreted as metabolites?
    Clh = ClT (1-fe)
  35. What are the units for clearance?
  36. What does bile contain?
    • water
    • bile salts
    • bile pigments
    • electrolytes
    • cholesterol
    • fatty acids
  37. What is restrictive clearance?
    elimination of unbound drugs
  38. What is non-restrictive clearance?
    when drugs are metabolized very rapidly by the liver and excreted
  39. What is the GFR of a normal male adult?
    125 ml/min
  40. How do we find biliary clearance?
    Clbiliary = (bile flow)(Cbile)/ Cp
  41. What is the avg bile flow in humans?
    0.5-0.8 ml/min
  42. What enzyme is responsible for enterohepatic recirculation?
    glucuronidase enzyme hydrolyzed the metabolite back to the parent drug in the intestines = reabsorption
  43. When is enterohepatic circulation important?
    after multiple doses or after a very high dose of drug
  44. What does fecal drug excretion represent?
    unabsorbed drug
  45. How do we know what the excretion rate in the kidney is (what factors do we have to consider)?
    • excretion rate: GFR + Tubular Secret Rate - reabsorption rate
    • So, ClR= GRF + TSR - reabsorption/ Cp
  46. How do we find the clearance RATIO?
    clearance of drug/ clearance of inulin
  47. If there is filtration only, and no reabsorption, what equation do we use to find clearance?
    • ClR = ke * Vd
    • ke = ClR/ Vd
    • if no plasma protein binding: ClR = GFR
  48. If there is filtration and reabsorption, how does that affect the amount of drug excreted?
    the rate is reduced
  49. How do we find drug excretion RATE if we have filtration and reabsorption?
    • dDu/dt = ClRCp (1-fr)
    • fr: reabsorption factor
  50. How are T1/2 and Vd related?
    the bigger the Vd, the longer/bigger the T1/2 will be
  51. Are protein bound drugs eliminated via GFR?
  52. How are protein bound drugs eliminated?
    active tubular secretion
  53. What is the relationship between T1/2 and clearance?
    as T1/2 increases, clearance decreases
  54. How do we find T1/2 when we know Vd and clearance?
    T1/2 = 0.693Vd/ ClT
  55. Can we change the pKa of a drug?
  56. Drugs with a high first pass effect have what kind of extraction ratio?
    high ER
  57. Name some drugs with a high ER.
    • propanolol
    • diltiazem
    • morphine
    • lidocaine
  58. Which organ regulates volume and composition of plasma and interstitial fluid?
  59. What are the two main functions of the kidney?
    • regulate blood pressure
    • regulate electrolytes
  60. Which organ maintains acid-base pH balance?
  61. Where does excretion occur?
    • sweat
    • saliva
    • milk
    • bile
    • urine
    • lungs
  62. Where does biotransformation occur?
    • small intestine
    • skin
    • liver
    • kidney
  63. What are the 3 basic processes of renal drug excretion?
    • glomerular filtration
    • active tubular secretion
    • tubular reabsorption
  64. What is glomerular filtration driven by?
    hydrostatic pressure in the glomerular capillary
  65. Which renal drug excretion process is unidirectional and nonselective?
    glomerular filtration
  66. What type of molecules undergo glomerular filtration?
    • small molecules ( MW less than 500 daltons)
    • amino acids
    • free drug
    • glucose
    • electrolytes
  67. What is the glomerular filtration directly related to?
    plasma concentration of free drug
  68. What two molecules do we use to measure GFR?
    • inulin
    • creatinine
  69. the use of probenicid and penicillin is an example of what elimination process in the kidney?
    active tubular secretion
  70. This process is the transport of drugs against a concentration gradient in the kidney and requires energy, is carrier mediated, saturable, capacity limited and competitive?
    active tubular secretion
  71. This elimination process in the kidney can be either active or passive?
    tubular reabsorption
  72. This method of excretion in the kidney is affected by the pH of the urine and the pKa of the drug?
    tubular reabsorption
  73. What type of drug is better reabsorbed in the kidney?
    undissociated (fat soluble)
  74. Relative solubilities of drugs (the partition coefficient) depends on what 2 things?
    • pH of solution (urine)
    • pKa of the drug (always constant)
  75. What is absorbed better? ionized or unionized
  76. For a weak acid, how do we find ionization?
    ionized/unionized = 10pH - pKa
  77. For a weak base, how do we find ionization?
    unionized/ionized = 10pH- pKa
  78. Where is Pgp found?
    • intestinal epithelium
    • hepatocytes
    • renal proximal tubular cells
    • capillary endothelial cells in the BBB
Card Set
Exam 3
power point slides, lecture notes, equations