Pharmacokinetics

Absorption
1. Transfer from site of admin to systemic circulation
2. Increase SA = Increased speed of A
3. Aq vehicle - Rapidly A
Elimination
1. Metabolism
  1. Phase one
    1. Oxidation
      1. Hydroxylation
      2. Epoxide
      3. Dealkylation
      4. Deamination
    2. Reduction
    3. Hydrolysis
  2. Phase Two- conjugation
    1. Sulphation
    2. Glucuronidatiom
    3. Amino Acid
    4. Acetylation
    5. Methylation
  3. Phase three
    1. Cytochrome P450
  4. Kinetics
    Annotations:
    - A. -->. A(m). --> Ae(m) Km. K(m)
2. Excretion
3. Irreversible removal of drug from the body
4. Clearance
  1. Total CL=Hepatic CL + Renal CL+ other CL
  2. CL=QxE
    1. <90L/hr , (1.5L/min)
    2. High E drug
      1. CL=Q
    3. Low E drug
      1. CL=CLint x Fu
  3. CL=Dose/AUC
  4. CL=KV
    1. T1/2=ln2V/CL
  5. Independent of plasma conc, dependent on efficiency
    1. First order kinetics
      1. Rate=Vmax x C / Km + C
  6. Vol of plasma/blood completely cleared of drug in a given time.
  7. Greater CL -> smaller AUC, shorter t1/2, same V
  8. Renal CL= GFR x Fu
    1. 125mL/min
5. Rate of E= CLxPlasma conc.
  1. Extraction ratio= rate of E/ presenting conc.
    1. Extraction Ratio= (Cart - Cven)/ Cart
6. Bioavailable fraction (F)
  1. CL=FDose/AUC
    1. AUC only changed by absorption not by rate
  2. IV: 1
  3. Fraction of unchanged drug that reaches systemic circulation
7. Major - liver M, biliary Ex ! Kidney, urinary M&Ex
8. Minor - lung M, breath Ex, breast milk, skin, alimentary tract
Distribution
1. Transfer from one compartment to another
2. V (L)
  1. Vi, Vss
    1. Vss=Vp + Vt x (Fu/Fut)
  2. Vol of blood needed to account for the total amount of drug in the body
    1. Amount=Volume x Conc
3. One compartment model
  1. Instantaneous distribution
  2. V is constant
  3. K=E rate constant
  4. Enter text here
  5. 1st order
    1. Rate=Rate constant x amount
    2. Rate of e= CL x Conc
4. Two compartment model
  1. D equilibrium not instantaneous
    1. V increases with time until D equilibrium reached
  2. AUC=A/a + B/b
5. Central
6. Peripheral
7. CO=6L/min
8. Q= blood flow
  1. Lungs = 10ml/min
  2. Fat = 0.03ml/min
  3. HBF~ 1.5L/min
  4. Portal BF ~ 1.2L/min
  5. Artery ~0.3L/min
  6. Bile flow ~ 0.5mL/min
  7. Increased by massage and excercise. A is the rate cntrolling step.
9. Multi compartment
Routes
1. Injections
  1. Iv
  2. Intra Arterial- targets specific organs
  3. Spinal - drugs that don't cross the BBB. Not systemic. ABs, analgesics, antineoplastics
  4. Intraperitoneal - high vascularity, large SA. Lipophilic absorbed quickly but variable. Some HFPM. Local targettng, A not complete
  5. Intramuscular- High vascularity, variability between diff muscles. Deltoid 10.2 mcg/ml , GM 4.3, Vastus Leteralus 9.2
  6. Avoid HFPM
  7. Subcutaneous- Moderate vascularity, Q increased by heat + massage. Q is the ARL step. Limited fluid for dissolution. Local E activity; low. Mild pH
  8. Intradermal - V. poor vascularity, small SA. Variable permeability. Local E activity: low. A increased by heat and hydration

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Pharmacokinetics

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	Created by Beth Walton over 10 years ago