HIV Pharmacology Flashcards

1
Q

Describe the treatment goals of Antiretroviral therapy

A

maximal and durable suppression of of plasma viremia delays, improves or preserves CD4 T cell numbers

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2
Q

What are the predictors of virologic success in HIV patients

A
low baseline viremia 
high potency of ARV regimen 
Tolerability of Regimen 
Convenience of regimen 
Compliance
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3
Q

What do Nucleoside Reverse Transcriptase Inhibitors inhibit?

A

Reverse transcriptase by direct inhibition.

They are incorporated into DNA being made from HIV RNA and stops the process

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4
Q

What process must NRTIs go through to become activated?

A

phosphorylation

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5
Q

What determines NRTI toxicity and where are NRTIs universally toxic

A

the ability of NRTI to target only HIV reverse transcriptase without inhibiting host cell DNA polymerase

mitochondrial toxicity

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6
Q

Name the Thymidine analogue NRTIs

A

zidovudine (AZT)
stavudine

this is also the first line drug

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7
Q

Name the cytidine analogue NRTIs

A

Emtricitabine

Lamivudine

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8
Q

Name the guanosine analogue NRTI

A

abacavir

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9
Q

Name the adenosine analogue NRTI

A

tenofovir

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10
Q

True or false: ALL NRTI can select for resistance mutations

A

True

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11
Q

What are the toxicities associated with NRTI class

A

Lactic acidosis syndrome
peripheral neuropathy
pancreatitis

All due to mitochondrial toxicity

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12
Q

Which NRTI the only option for IV administration

A

zidovudine (AZT)

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13
Q

What are specific toxicities are possible with zidovudine

A

Bone marrow suppression
Skeletal muscle myopathy
Hepatic steatosis (potentially fatal)

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14
Q

What are the major toxicities associated with stavudine

A

peripheral neuropathy
NRTI most associated with lipodystrophy
Lactic Acidosis and hepatic steatosis

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15
Q

how effective is emtricitabine as a monotherapy to resistance

A

low

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16
Q

What other virus is emtricitabine effective against

A

HBV

DC of this drug can cause rebound effects

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17
Q

What other NRTI drug can emtricitabine be combined with as a superior combination

A

tenofovir

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18
Q

Describe the pharmacokinetics of emtricitabine

A

long intracellular half life (a current NRTI of choice)

excreted primarily as unchanged drug in urine

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19
Q

Describe the toxicity of emicitrabine

A

one of the lease toxic antiretroviral but prolonged use leads to hyperpigmentation of skin especially in palms and soles (most common in AA)

*Allison’s drug of choice

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20
Q

What antiviral drug was lamivudine co-formulated with?

A

tenofovir

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21
Q

Describe the pharmacokinetics of lamviduine

A

long intracellular half-life and excreted primarily as unchanged in urine

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22
Q

Describe the toxicity of lamivudine

A

one of the least toxic

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23
Q

What NRTI is the only guanosine analogue

A

abacavir

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24
Q

Is abacavir effective against HBV

A

nope

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25
Q

What genotype is fatally incompatible with abacavir

A

HLA-B*5701 - potential hypersensitivity syndrome

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26
Q

How is abacavir eliminated from the body

A

NOT CYP substrate. uses dehydrogenases and is glucuronidated

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27
Q

Describe the hypersensitivity syndrome in those who take abacavir

A

fever
abdominal/GI pain
maculopapular (looking at you allison) rash

*avoid in people with CAD due to hyplerlipidemia

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28
Q

How does tenofovir work as an NRTI

A

it is a nucleotide reverse transcriptase inhibitor

It is also approved to treat HBV

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29
Q

Describe the pharmacokinetics of tenofovir disoproxil fumarate

A

intracellular half-life of 10-50 hrs

excreted primarily as unchanged in urine

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30
Q

Describe the toxicities of tenofovir disoproxil fumarate

A

nephrotoxicity with acute tubular necrosis -> fanconi syndrome

decreased bone mineral density

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31
Q

how is Tenofovir alafenamide transported differently than tenofovir disoproxil fumarate

A

lower doses mean lower plasma concentrations but higher intracellular concentrations

*less renal toxicity than TDF

32
Q

Describe how most ART treatments are built

A

NRTI backbone with two each targeting a different base (ie emtricitabine + tenofovir) with another drug from another class

33
Q

Why would emtricitabine and lamivudine not be prescribed together as an NRTI backbone?

A

both inhibit the same bases

34
Q

what combination of drugs is recommended for treatment of naive patients unless HIV load is high

A

lamivudine and dolutegravir

35
Q

Describe the mechanism of action of integrase strand transfer inhibitors

A

Prevent the insertion of reverse transcribed DNA from viral RNA into host genome

36
Q

What drugs belong to the ISTI class

A

raltegravir
dolutegravir
bictegravir

37
Q

How is raltegravir eliminated

A

9 hour half life

eliminated in urine and feces as unchanged drug also undergoes glucuronidation

38
Q

describe dolutegravir and bictegravir’s barrier to drug resistance

A

it has a high barrier to drug resistance

39
Q

Describe the toxicities of dolutegravir

A

rare skin hypersensitivity

possible immune reconstitution syndrome

avoid in pregnancy

40
Q

how can the availability of bictegravir be affected

A

inducers or inhibitors of CYP3A4 but needs very potent agents to alter effects relatively stable

41
Q

Describe the mechanism of action of protease inhibitors

A

prevent the cleaving of the HIV virion propeptide into a functional viron.

42
Q

How do protease inhibitors inhibit viral aspartyl proteases but not human aspartyl proteases

A

virus protease is a homodimer while human are monomer

43
Q

What enzyme is most responsible for metabolism of protease inhibitors

A

CYP3A4

ritonavir is used to boost CYP3A4 activity

44
Q

List all the drugs in the protease inhibitor class

A
saquinavir 
indinavir 
darunavir 
atazanavir 
Lopinavir
45
Q

Describe the toxicity of saquinavir

A

GI distress

long term -> lipodystrophy

46
Q

Why is indinavir no longer recommended or prescribed

A

unique crystalluria/renal stones

47
Q

describe the specific mechanism of action of darunavir

A

a non-peptidic protease inhibitor

48
Q

what is the offlable use of darunavir

A

post-exposure prophylaxis

49
Q

Describe the pharmacokinetics of darunavir

A

15 hour half life when boosted
CYP3A4
80% excreted in feces
40% unchanged drug

Current PI of choice

50
Q

Describe the toxicities of darunavir

A

GI distress

cholesterolemia

fat redistribution syndrome

immune reconstitution syndrome

sulfa drug -> hypersensitivity

51
Q

describe the toxicities of atazanavir

A

GI problems

Elevated unconjugated bilirubin not associated with hepatitis

hypersensitivity

immune reconstitutions

52
Q

Which drug is prescribed after other PI -containing regimens fail

A

Lopinavir

53
Q

Which drugs are CYP3A4 inhibtors

A

ritonavir

cobicistat

54
Q

Describe the mechanism of action Non-nucleoside reverse transcriptase inhibitors

A

denatures the viral reverse transcriptase to inhibit the process. Binds the p66 subunit which induces conformational change; non-competitive antagonist

55
Q

Which type of HIV is NNRTI effective against

A

HIV-1

56
Q

how does resistance develop in NNRTI

A

a single aa substitution is enough. a single exposure to nevirapine in absence of other drugs is enough to induce resistance in 1/3 of HIV infected people

57
Q

What are the drugs in the NNRTI class

A
nevirapine
efavirenz
etravirine
rilpivirine 
doravirine
58
Q

What is a consideration with respect to birth control when taking nevirapine

A

reduces level of oral contraceptives so alternative method is needed

itching rashes most common side effect

59
Q

Describe the toxicity of efavirenz

A

CNS toxicity/psychiatric side effects

was considered teratogenic but not anymore?

60
Q

When should efavirenz not be prescribed

A

don’t add to failing regiment

61
Q

describe a unique function in the etravirine drug

A

it still works after mutations that disrupt activity of other NNRTI

62
Q

Describe the toxicity of etravine

A

fat redistribution
immune reconstruction syndrome
rash is common and resolves spontaneously
Stevens-johnson syndrome is possible

63
Q

Which NNRTI is the newest

A

doravirine

still not top choice though

64
Q

Describe the mechanism of action of the Entry Blockers - HIV Fusion Inhibitor

A

Prevents the binding of the HIV virion binding CD4 t cell area.

65
Q

What class of medication does enfuvirtide belong to

A

HIV fusion inhibitor

66
Q

What are the main effects of enfuvirtide

A

inhibits infection of CD4 by free virus particles

inhibits cell-to-cell transmission in vitro

67
Q

Which drug would be most appropriate if you needed to include a drug effective against HIV-2

A. enfuvirtide
B.Doravirine
C. Lopinavir
D. Rilpivirine

A

C. Lopinavir

68
Q

Describe the mechanism of action of the CCR5 blockers

A

prevent the binding of the gp120 and gp41 to the CD4 and CCR5 binding region

69
Q

Which class of medication does maraviroc belong to

A

CCR5 blocker

70
Q

What must be done before prescribing maravoc to ensure effectiveness?

A

phenotypic test to determine if CCR5 or CXCR4 tropism. NOT effective against CXCR4. test is very expensive. it the gucci of tests

71
Q

how is maravoc eliminated

A

CYP3A4 metabolism with renal excretion

72
Q

Who is ART recommended for?

A

Everyone!! and immediately

73
Q

True or False: a person who has a viral load of <200 copies/mL can have unprotected sex without transmitting their HIV

A

technically true but contingent on heavy heavy adherence. Slipping up in compliance will cause bounce back viral load in your load

74
Q

What are the 3 ART considerations

A
  1. Always use combo therapy
  2. current emphasis on tolerance and convenience
  3. based on realization that therapy must be life long
75
Q

If a treatment fails, what should be considered

A
  1. Adherence
  2. drug-drug/drug-food
  3. tolerability
  4. HIV RNA level

adding one new drug to a failed regimen is NOT recommended