drug absorption and distribution Flashcards

1
Q

3 factors to consider in drug absorbtion

A
  1. drug properties
  2. patient factors
  3. possible routes of admin
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2
Q

4 mechanisms of drug absorption (cellular)

A
  1. passive diffusion
  2. facilitated diffusion
  3. active transport
  4. phagocytosis
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3
Q

3 properties of drugs that affect absorption

A
  1. chem structure size etc.
  2. lipid and water solubility
  3. ionization
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4
Q

what is usual molecualr weight of drugs

A

250-450 Da

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5
Q

at what size can a lipid soluble drug diffuse across membrane

A

1000Da

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6
Q

what is partition coefficient

A

[drug in membrane]/[drug in buffer]

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7
Q

what does higher partition coeff. mean

A

more lipid soluble

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8
Q

what increase and decrease PC

A

incr- hydrophobic groups (benzene, CH3)

dec. - hydrophilic groups - OH, COOH,

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9
Q

what is the effect of drug ionization

A

uncharged form is generally easier to cross membrane

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10
Q

** what happens with higher Ka in acid and basic drug - when increase pH over pKa

A

acid - more ions

basic - less ions

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11
Q

what are drug transporters

A

proteins responsible for moving drugs into and out of cells

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12
Q

most common locations of transporters

A

apical layer of hepatocytes, enterocytes, tubular cells

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13
Q

2 main classes of drug tranporters

A
  1. uptake transporters

2. efflux transporters

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14
Q

why are transporters relevant

A
  1. also affects distribution and elimination

2. need to know if drug is a substrate, inhibitor, or inducer of transport

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15
Q

what is volume of distribution

A

volume of total body fluid that is absorbing the drug

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16
Q

4 drug properties that influence distribution

A
  1. size and structure
  2. lipid solubility
  3. degree of ionization
  4. protein binding
17
Q

3 other factors affecting distribution

A
  1. blood flow
  2. cap. permiability
  3. barriers
18
Q

what are the 3 body compartments and avergae size for 70kg male

A
  1. water - 42L
  2. fat - 14L
  3. bone - 5L
19
Q

what is apparent vol. of distribution

A

hypothetical vol. into which drug is disseminated

20
Q

when is apparent vol used

A

when want to compare withing different compartments of body

21
Q

formula for Vd

A

total drug in body/intial plasma [c]

22
Q

what does app Vd tell us

A

an idea if the drug is beyond the plasma

23
Q

when does knowing Vd help

A
  1. idea of where drug might be distributed
  2. when predicting plasma [C]
  3. determining dose of drug to produce desired plamsa [C]
  4. deciding whether to dyalize when poisoned