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SBM Pharm term 1 > pharmacokinetics I and II > Flashcards

pharmacokinetics I and II Flashcards

1
Q

what is absorption?

A

movement of drug from site of admin to blood

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2
Q

what is distribution?

A

delivery of drug from blood to tissues

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3
Q

what is bioavailability?

A

amount that actual reaches the target in biologically active form after crossing lipid membranes, binding proteins, tissue storage, metabolism, excretion

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4
Q

what is the partition coefficient?

A

how much a drug likes fat vs water, higher number represents how much drug is in fat vs water.

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5
Q

Pka rule of thumb

A

lower an acids pka the stronger it is, higher a base’s pka the stronger it is

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6
Q

ionization rule of thumb

A

bases are ionized in acidic environment (BH+)

acids are ionized in basic environment (A- + H+)

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7
Q

absorption in mouth

A
  • drugs with high partition coefficient and favorable pka

- absorption 4 times faster than in GI, but passage is fast

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8
Q

absorption in stomach

A
  • only weak acids

- most drugs are weak bases

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9
Q

absorption in small intestine

A

mostly by first 1-2 meters of proximal jejunum

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10
Q

why are pH and pka so crucial in small intestinal absorption?

A

diffusion is passive

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11
Q

large intestine absorption

A

not as much as small intestine, not as vascularized

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12
Q

why do suppositories work?

A

rectal blood doesn’t go straight to liver

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13
Q

absorption in lung

A

highly vascularized, high surface area, lipophilic so favors high partition coefficient, many things can get in through the lungs

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14
Q

advantages of IM or SC injection

A

rapid, precise, large volumes,

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15
Q

disadvantages of IM or SC injection

A

pain, necrosis, nerve damage

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16
Q

advantages of IV

A

direct, good for narrow TI, good for those with low absorptive capacity

17
Q

disadvantages of IV

A
  • easier to overdose
  • risk of embolism or microbial contamination
  • local necrosis or immune reaction
18
Q

drug accumulation in five places in the body

A

1) kidney - highly susceptible to toxicity due to high blood flow
2) eye - melanin can bind drugs
3) fat - high partition coef, slow in slow out
4) lung - accumulates basic amines
5) bone - VERY slow in and out

19
Q

what is K-el?

A

time constant for drug elimination

20
Q

how is K-el related to half life?

A

K-el = .693 / half life or half life = .693/K-el

21
Q

what is Co?

A

initial concentration of the drug

22
Q

what is Vd and its formula?

A

volume of distribution

Vd = D (dose)/Co (initial concentration)

23
Q

what is Clp? what is its formula?

A

Clp (clearance) = K-el (elimination constant) x Vd (volume of distribution)

24
Q

what is Css?

A

steady state concentration, what you are trying to maintain with a maintenance dose.

25
Q

what is a maintenance dose (MD)?

A

dose at a specified dosing-interval required to achieve a specific steady state concentration

26
Q

what is the maintenance dose formula?

A

MD = Css x Vd x K-el x dosing interval = Css x Clp x dosing interval

27
Q

what is D*?

A

loading dose

28
Q

what is the loading dose formula?

A

D* = Css x Vd

29
Q

when are loading doses given?

A

when a drug has a long half life but you want to achieve a therapeutic concentration quickly

30
Q

what is F?

A

oral fraction - bioavailability, the fraction that enters orally vs IV

31
Q

what is the oral fraction formula?

A

F = AUCoral/AUCiv

32
Q

formula for oral loading dose

A

D* oral = Css x Vd x 1/F

33
Q

oral maintenance dose formula

A

MDoral = Css x Vd x K-el x 1/F

34
Q

two half life formulas

A

t 1/2 = .693/K-el

t 1/2 = .693/[Vd/Clp]

35
Q

define clearance

A

the portion of a compartment that has been cleared of a drug per unit time

SBM Pharm term 1 (9 decks)

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