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Apex Review > Pharmacokinetics 2 > Flashcards

Pharmacokinetics 2 Flashcards

1
Q

In which circumstance is a drug MORE likely to pass through a lipid membrane?
a. a weak base where the pH of the solution is > the pKa of the drug
b. a weak base where the pH of the solution is < the pKa of the drug
c. a weak acid where the pH of the solution is < the pKa of the drug
d. a weak acid where the pH of the solution is > the pKa of the drug

A

A & C

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2
Q

Ionization describes the process where

A

a molecule gains a positive or negative charge; this affects a molecule’s ability to diffuse through lipid membranes

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3
Q

A drug’s pKa equals the pH where

A

50% of the drug is ionized and the other 50% of the drug is non-ionized

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4
Q

Ionization affects a drug’s

A

pharmacologic activity as well as its ability to pass through cell membranes

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5
Q

A drug that’s a weak acid will

A

donate a proton to water (pH = 7)

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6
Q

A drug that’s a weak base will

A

accept a proton from water (pH= 7)

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7
Q

An acid is a substance that

A

donates a proton
HA+ <–> H+ + A

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8
Q

A base is a substance that

A

accepts a proton
B- +H+ <–> BH

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9
Q

The pH measures the concentration of

A

hydrogen ions in an aqueous solution

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10
Q

If you put a strong acid or a strong base in water, it will

A

dissociate completely

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11
Q

If you put a weak acid or a weak base in water,

A

a fraction will ionize, and the remaining fraction will be non-ionized

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12
Q

Ionization is dependent on the following two factors:

A

the pH of the solution
the pKa of the drug

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13
Q

The pKa tells us how much

A

a molecule wants to behave like an acid
low pKa= amazing acid
high pKa= terrible acid

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14
Q

In an acidic solution, weak bases are

A

more ionized and water-soluble

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15
Q

In a basic solution, weak bases are

A

more non-ionized and lipid-soluble

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16
Q

In an acidic solution, weak acids are

A

more non-ionized and lipid-soluble

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17
Q

In a basic solution, weak acids are more

A

ionized and water-soluble

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18
Q

A weak acid is paired with a positive ion such as

A

sodium, calcium, or magnesium

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19
Q

A weak base is paired with a negative ion such as

A

chloride or sulfate

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20
Q

Describe the solubility of an ionized drug

A

water soluble- hydrophilic, liphophobic

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21
Q

Describe the diffusion of an ionized drug across lipid bilayers.

A

does not diffuse across blood-brain barrier, GI tract, and placenta

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22
Q

Does an ionized drug have an active or inactive pharmacologic effect?

A

not active

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23
Q

Describe hepatic biotransformation and renal elimination for an ionized drug.

A

hepatic biotransformation- less likely
renal elimination- more likely

24
Q

Describe the solubility of a non-ionized drug.

A

lipid soluble
-liphophilic
-hydrophobic

25
Q

Describe the pharmacologic effect on a non-ionized drug.

A

active

26
Q

Describe the diffusion across lipid bilayers for a non-ionized drug.

A

diffuses across blood-brain barrier, GI tract, & placenta

27
Q

Describe the hepatic biotransformation and renal elimination of a non-ionized drug.

A

hepatic biotransformation- more likely
renal elimination- less likely

28
Q

Which circumstance creates the STRONGEST gradient for the passage of local anesthetic from the mother to the fetus?
a. maternal acidosis and fetal acidosis
b. maternal acidosis and fetal alkalosis
c. maternal alkalosis and fetal acidosis
d. maternal alkalosis and fetal alkalosis C.

A

C.- maternal alkalosis and fetal acidosis

29
Q

Fetal pH is typically _____ than maternal pH

A

lower

30
Q

Lower fetal pH can lead to

A

ion trapping and increased fetal drug concentrations

31
Q

The combination of ________ & __________ worsens the problem of ion trapping in the fetus.

A

maternal alkalosis & fetal acidosis

32
Q

Of the commonly used anesthetics for neuraxial anesthesia, _______ is most likely to undergo fetal ion trapping.

A

lidocaine

33
Q

Of the commonly used anesthetics for neuraxial anesthesia, _________ is least likely to undergo fetal ion trapping.

A

chloroprocaine

34
Q

If a drug is 98% bound by plasma protein, and the bound fraction decreases to 96%, the free fraction will increase by

A

100

35
Q

Plasma proteins include

A

albumin, alpha 1-acid glycoprotein, and beta-globulin

36
Q

Albumin primarily binds with

A

acidic drugs

37
Q

Alpha 1-acid glycoprotein and beta-globulin typically bind with

A

basic drugs

38
Q

These conditions can decrease protein concentrations

A

liver disease, renal disease, old age, malnutrition, and pregnancy

39
Q

_______ synthesizes plasma proteins

A

The liver

40
Q

A drug bound to a plasma protein cannot

A

bind to a receptor nor can it be cleared by a clearing organ

41
Q

The extent of plasma protein binding affects the

A

intensity of drug effect effect and the drug’s duration of action

42
Q

The most plentiful plasma protein is

A

albumin

43
Q

Albumin is decreased by

A

liver disease
renal disease
old age
malnutrition
and pregnancy

44
Q

Alpha 1 acid glycoprotein concentration is increased by

A

surgical stress
myocardial infarction
chronic pain
rheumatoid arthritis
advanced age

45
Q

Alpha 1 acid glycoprotein concentration is decreased by

A

neonates
pregnancy

46
Q

The percent increase formula is:

A

percent change= ((new value- old value)/old value)) x 100%
positive result= increase
negative result= decrease

47
Q

Changes in protein binding can result from

A

decreased plasma protein content or competition for binding sites on the protein

48
Q

Factors that decrease plasma protein include

A

reduced synthetic function (liver disease, malnutrition)
altered distribution (3rd trimester of pregnancy)
increased protein excretion (renal disease)

49
Q

The volume of distribution is ______- related to the degree of plasma protein binding

A

inversely

50
Q

Highly protein-bound drugs typically have a ______ rate of metabolism and elimination

A

slower

51
Q

The risk of adverse effects is greatest when a drug has a

A

narrow therapeutic index

52
Q

Alterations in plasma protein binding can be a problem in several situations such as during

A

CPB (hemodilution and heparinization) as well as in ECMO circuits

53
Q

Which kinetic model describes the process that metabolizes a constant amount of drug per unit time?
a. zero order
b. first order
c. second order
d. third order

A

a. zero order

54
Q

Describe zero order kinetics.

A

constant amount of the drug is metabolized per unit time

55
Q

Describe first order kinetics.

A

constant fraction of the drug is metabolized per unit time

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