S3M1 pharm

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sweetlu
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154410
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S3M1 pharm
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2012-05-21 09:30:01
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S3M1 pharm
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S3M1 pharm
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  1. ionization of base
    - most ionized: pKa > pH (H2O sol)

    - least ionized: pKa < pH
  2. ionization of acid
    - most ionized: pKa < pH (H2O sol)

    - least ionized: pKa > pH
  3. - how long does it take to reach steady state concentration without a loading dose
    - 4 t1/2 (4 half lives)
  4. lipid diffusion
    • - most common way drugs cross cell membrance
    • -
  5. aqueous diffusion
    - restricted to solutes with MW < 100
  6. percentage of nonionized or ionized drug as a function of the difference between pKa and pH
    • 0= 50%
    • 0.5= 76%
    • 1= 90%
    • 2= 99%
    • 3= 99.9%
    • >3= >99.9%
  7. ion trpping
    • - process by which [drug] can climb very high compared to the [drug] outside the cell. This can be the result of change in pH and b/t ionized and non-ionized forms once it reached the inside of the cell
    • - ie ASA mostly lipid solube(non ionized) in the gut lumen (low pH) and then mostly H2O soluble in the cells (pH=7), this results in the ions being trapped within the cell
  8. acidic drugs
    - mostly ionized/H2O soluble when pKa<pH
  9. drugs that cross cell membranes via endo/exocytosis
    - 2000-100,000 MW
  10. Drugs that travel via bulk flow/filtration/convective transfer
    • - up to 40,000 MW
    • - passive
    • - non selective
  11. first order kinetics
    - a contant fraction (or percentage) of a drug is absorbed, distributed or eliminated per unit time
  12. zero order kinetics
    • - a constant amount of the drug is absorbed, distributed or eliminated per unit time
    • - accounts for very few drugs
  13. bioavailabilty (F) based on AUC
    - F= AUCx/AUCiv
  14. gas administration
    • - most rapid
    • - acheive systemic effects
    • - absorption is directly proportional to the Px of the gas in the alveoli
  15. aerosol administration
    • - absorption is usually slow and very limited
    • - acheive local effects
  16. SC and IM administration
    • - absorption occurs mainly via bulk-flow transfer thru intercellular pores of endothelium of b/v
    • - SM (10-30 min)
  17. volume of distibution (Vd)
    • Vd = D x F/ Cp0 (independent of dose)
    • D = dose, F = bioavailability, Cp0 = [drug]pl at zero time
    • Vd~3L: distribution restricted to vascular compartment
    • Vd~13L: distibution thruout EC fluid, cant penetrate cells
    • Vd~42L: distribution is in total body water
    • Vd>42L: drug extensively stored w/in specific cells/tissue
  18. initial dose calculation
    • - D = (Vd x C0)/F
    • - desired [drug]pl must be known
  19. drug binding
    • - albumin if acidic
    • - alpha1-acid glycoprotein if basic
    • - binding is a constant percentage (independent of dose)
    • - saturable
    • -**competition can occur**(very relevant if binding is >90-95%, because a competitor can cause a large increase in [drug]pl
  20. circumventricular organs (cerebral regions outside the BBB)
    • - posterior pituitary
    • - median eminence of the HT
    • - Supraoptic crest
    • - Subfornical organ
    • - area postrema
  21. placental drug transfer
    • - <1000 MW
    • - greater with lipophilic drugs
    • - highly ionized drugs 200MW or higher cross slowly andpoorly
    • - greater with un-protein bound drugs
    • - easier in 3rd trimester
  22. main monooxygenases
    - NAPDH- cytochrome P450 reductase and ctyochrome P450
  23. UDP- glucuronosyltransferase
    - microsomal enzyme in the liver responsible for glucuronidation, the most common conjugation reaction of xenobiotics
  24. microsomal enzymes
    • - SER of the liver cyt P450
    • - very low substrate specificity
    • - only works with lipid soluble xenobiotics
    • - mainly oxidations and glucuronidations
    • - inhibited by cimetidine, amiodarone and SSRI's
    • - induced by barbituates and rifampin
  25. non microsomal drug metabolizing enzymes
    • - catalyze mainly conjugations, hydrolysis and redox
    • - synthesis is under genetic control
    • - can be inhibited, but NOT induced
    • - products usually more H2O sol
    • -variable substrate specificity
  26. renal clearance of a drug
    • CL = (F x Ud)/ Pd
    • F= urine flow rate
    • Ud= [drug]urine
    • Pd= [drug]pl
  27. renal drug elimination
    • CL= 100-150 ml/min: glomerular filtration
    • CL>150 ml/min: tubular secretion
    • CL<100 ml/min: reabsorption (or protein binding)
  28. half life
    • t1/2 = 0.7 (Vd/CL)
    • **a drug is considered to be essentially eliminated from teh body after four half-lives**
  29. Steady state [drug]
    • Css = (F x D)/ (Cl x T)
    • F= bioavailability D= dose
    • Cl= total clearance T= infusion time
    • **TIME to reach Css is determined by elimination half-life only
  30. Css simple
    • = 4t1/2
    • - 94% plasma concentration is reached after 4 half lives
    • - Css = 2 x [drug]pl after 1 half life
    • *if dosing interval is <4t1/2, than accumulation will occur*
  31. Css long equation
    Css = (F x D x t1/2)/ (T x 0.7 x Vd)
  32. Loading dose
    Loading dose= (Vd x Cp)/F
  33. Maintenance dose
    Maitenance dose/T = (Cl x Css)/F
  34. rate of infusion=rate of elimination
    D/T = Css x CL
  35. drugs that follow zero order kinetics
    - EtOH, salicylic acid and phenytion
  36. dosing rate
    DR = Css x total CL
  37. Theraputic index
    • - TD1/ED99 **margin of safety**
    • -TD50/ED50
  38. immunogenic molecules
    have a MW or 6000 or higher or can function as a hapten (covalently bond to a protein forming an immunogenic compound)
  39. teratogen effects on embryo stage
    • blastogenesis= death of embryo or total recovery
    • organogenesis= most sensitive to morphological effects
    • histogenesis= most sensitive to metabolic/fuctional effects (often appear only after many years)
    • **TOXIC effects are most frequent in last months of prego*
  40. teratogen
    • - dosage dependent
    • - prego stage very important
    • - category D and X drugs should be avoided
  41. carcinogens
    • - dose dependent, additive and irreversible
    • - many are also mutagenic (malformation that can be passed on in gametes)

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