HTN PK Flashcards

1
Q

which CCB has the longest half-life?

A

amlodipine (33hrs)

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2
Q

which CCB has the highest F?

A

amlodipine (64%)

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3
Q

what is the issue with short-acting nifedipine?

A

cause major fluctuations in BP due to quick inset and offset and this can lead to things like MI and stroke

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4
Q

most CCBs are metabolized by what enzymes?

A

CYP3A4 and CYP3A5

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5
Q

t/f most CCBs show stereoselective PK

A

t

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6
Q

which CCBs have active metabolites?

A

diltiazem and verapamil

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7
Q

why does nifedipine not show stereoselective PK?

A

it is achiral

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8
Q

what is stereoselective metabolism?

A

preference of drug metabolizing enzymes for one enantiomer over the other

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9
Q

stereoselectivity influences the degree of ___

A

hepatic first pass F and rate of metabolism

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10
Q

for most CCBs, which enantiomer is greater?

A

R

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11
Q

verapamil and diltiazem and its metabolites are potent inhibitors of ___ and ___

A

CYP3A4 and PGP

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12
Q

formula for clearance

A

dose/AUC

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13
Q

which antibiotics do CCBs have a tendency to interact with?

A

macrolides (erythromycin and clarithromycin, not so much azithromycin)

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14
Q

most ACE-I have ____(high/low) protein binding

A

low

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15
Q

most ACE-I have low Vd, except ___

A

linsinopril

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16
Q

the fraction unbound (Fu) is expressed as the ration of _____

A

concentration of unbound drug to the concentration of total drug

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17
Q

give 2 examples of things that can influence the Fu

A

drugs and disease state

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18
Q

list 7 things that can affect drug distribution and protein binding

A
  1. physiochemical properties of drug (lipid solubility, ionization, pka)
  2. pH differences of biological fluids (affects permeability)
  3. blood flow through organs
  4. drug transporters and efflux pumps
  5. extent of protein binding
  6. amount of drug-binding proteins which can be affected by liver dx
  7. Binding inhibitors and drugs (may displace or alter conformation)
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19
Q

what is Vd?

A

a hypothetical volume with no physiological or anatomical meaning. It is a characteristic PK parameter of a drug indicating distribution between plasma and other binding sites where drug is distributed

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20
Q

how is Vd calculated?

A

Dose/plasma drug concentration (free and unbound)

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21
Q

how is Vd calculated for an IV drug?

A

amount of drug in body / plasma drug concentration

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22
Q

if a drug distributes well to tissues, it will have a ___(large/small) Vd?

A

large

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23
Q

if a drug is bound to plasma proteins but not to tissue proteins, the Vd will be ____ (small/large)

A

small

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24
Q

if a drug is highly bound to tissue proteins, the Vd will be ____ (small/large)

A

large

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25
what are 3 applications of Vd in practice?
1. knowing where drug is in the body 2. calculation of dose and amount in body 3. dose adjustment
26
how is the amount fo drug in the body (dose) calculated?
concentration x Vd
27
most ACE-I are prodrugs except ___ and ___
captopril and linsinopril
28
what type of prodrugs are ACE-I, how are they activated?
ester-prodrugs; converted by esterases like CES1/2 in the liver
29
most active metabolites of ACE-I are inactivated by ____
UGTs in the kidneys, the CYPs are not involved
30
is linsinopril metabolized?
no, it is excreted unchanged in the urine
31
what is the effect of ACE-I in patients with renal dx?
have a large, unpredictable increases in AUC and since ACE-I also get excreted by the liver, the amount excreted in the feces will increase
32
what did the FDA recommend for the trough to peak ratio?
the placebo corrected trough effect should be at least one-half of the placebo corrected peak effect (T:P more than 50%)
33
which 3 ACE-I exhibit T:P>50%?
fosinopril, ramipril, trandolapril
34
which ARBs are prodrugs?
losartan and olmesartan
35
how is losartan turned into its active EXP3174 form?
metabolized by CYP2C9 through an oxidative reaction that converts OH group to an acid group
36
do ARBs show stereoselective pk?
no, they dont have a chiral center
37
most ARBs are metabolized by which enzyme?
CYP2C9
38
most ARBs have a high ___
hepatic peak extraction ratio
39
out of ACE-I and ARBs, which have a higher protein binding?
ARBs
40
out of ACE-I and ARBs, which has fewer ADRs in end-stage renal disease?
ARBs (bc they are more hepatically cleared?)
41
which 2 ARBs have the least renal excretion?
irbesartan and telmisartan
42
the ocurrence and extent of CNS effects of B blockers depends on the ___ of the B blocke
lipophilicity
43
which B blocker has the highest lipophilicity?
propranolol
44
beta blockers are metabolized by what enzymes?
various CYP enzymes
45
do B blockers have stereselective metabolism?
yes
46
most beta blockers have ___(high/low) hepatic extraction ratio
high
47
why are only a fraction of diuretics filtred by the glomerulus?
they are highly protein bound to plasma proteins
48
do OAT transport acids or bases
acids
49
loop diuretic and thiazides are secreted in the ___
tubules
50
thiazide and thiazide diuretics other than chlorothiazide have ___ (high/low) oral F
high
51
how are thiazide and like diuretics excreted?
mostly unchanged in the urine
52
high concentrations of thiazides is attained in the ___ fluid
luminal
53
most thiazides are weak __ (acids/bases)
acids
54
glomerular filtration is a passive process that depends on what 3 things?
1. protein binding (unbound drugs only) 2. molecular size (filtered when MW <500) 3. number of functional nephrons
55
lipophillic drugs are absorbed ____(actively/passively) in the tubules
passively
56
for weak acid drugs, what is the effect of pH on their tubule reabsorption>
higher pH increases the ionized component and increases drug excretion
57
for weak bases, what is the effect of pH on their tubule reabsorption?
as pH increases, the ionization decreases and the drug excretion decreases
58
active secretion in the renal tubules deoends on what 3 factors?
1. affinity of drug for transport protein 2. rate of delivery of drug to the secretory site 3. rate of transfer of drug across tubular membrane
59
what proteins are involved in active tubule secretion?
OAT, OCT, PGP, MrP, MATE
60
what is total drug clearance?
volume of blood/plasma/body fluid cleared of drug per unit time. The sum of cl by all routes of elimination (liver, kidney, lung etc.)
61
how is total clearance calculated?
(F x dose) / AUC
62
does total drug clearance indicate the amount of drug elimination?
no
63
how is extraction ratio (ER) calculated?
Concentration into liver-concentration leaving liver / concentration going into liver
64
if drug is completely eliminated in ONE passage through the liver, the EHR is equal to ___
1
65
if drug is not eliminated, the EHR is equal to __
0
66
low ER
<0.3
67
mild ER
0.3-0.7
68
high ER
0.7-1.0
69
what is hepatic clearance?
volume of blood from which a drug will be cleared by the liver per unit time
70
the hepatic clearance is a ratio of ___
hepatic elimination rate to plasma drug concentration
71
how to calculate hepatic clearance
Q x ER
72
for drugs with high hepatic ER, what is the rate limiting step?
flow
73
for drugs with low ER and low protein binding (<75-80%) what is the rate limiting step? Does it depend on proetin binding?
metabolism capacity; no
74
for drugs with low ER and high protein binding (>75-80%), what is the rate limiting step? Does it depend on protein binding?
metabolism capacity; yes
75
give 2 examples of drugs with high renal ER
penicillin G and glucuronides
76
for high renal ER drugs, the CLr is dependent on ____ and ___ is involved
blood flow; active secretion
77
give 2 examples of low renal ER drugs
gentamicin, tetracycline
78
for low renal ER drugs, the CLr is limited by ____
glomerular filtration rate
79
give examples of drugs that are enzyme inducers
phenytoin, carbemazepine, phenobarbital, rifampicin
80
give examples of drugs that induce CYP3A4
rifampicin/rifampin, carbemazepine and phenytoin
81
give examples of CYP2B6induceer
phenobarbital
82
what are the PK consequences of induction on the parent drug?
decreased plasma drug concentration, decreased AUC, decreased elimination half-life