Anti-Viral Drugs Flashcards

1
Q

List the 4 key Anti-HIV drugs (in our syllabus)

A
  1. NRTI: nucleoside reverse transcriptase inhibitors
  2. Integrase inhibitor
  3. Protease inhibitors
  4. NNRTI: non-nucleoside reverse transcriptase inhibitors
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2
Q

What is the standard treatment for HIV pxs.

A
  1. 2 NRTIs in combination with
  2. 1 other active ARV drug
    - integrase inhibitor (INSTI)
    - protease inhibitor w PK enhancer
    - non-nucleoside reverse transcriptase inhibitor (NNRTI)
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3
Q

What is the most favoured HIV regiment

A

2NRTIs + INSTI regimen

  • INSTI: integrase strand transfer inhibitor
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4
Q

List the common causes of treatment failure in HIV pxs.

A
  1. Poor adherence
  2. Drug resistance
  3. Poor absorption of medication
  4. Inadequate dosing
  5. Drug-drug interactions
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5
Q

What are some long-term toxicities HIV pxs face from antiretroviral therapy?

A
  1. Metabolic syndrome
  2. HIV lipodystrophy syndrome (unwanted redistribution of fat)
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6
Q

List the 5 NRTIs

A
  1. Emtricitabine
  2. Tenofovir
  3. Lamivudine
  4. Abacavir
  5. Zidovudine
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7
Q

What are the 2 NRTIs that are cytosine analogues?

A
  1. Emtricitabine
  2. Lamivudine

thus, they should not be administered tgt as they will be competing w each other -> ineffective

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8
Q

Name the 3 NRTIs that have anti-viral activity against Hep B too.

A
  1. Emtricitabine
  2. Lamivudine
  3. Tenofovir
  • hep B/HIV coinfection pxs on these drugs cannot just discontinue the drug as it well cause severe acute exacerbation of hepatitis should they discontinue
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9
Q

Which NRTI requires pxs to be genotyped for suitability before prescription?

A

Abacavir
- only pxs w the negative allele can take the drug (HLA-B*5701-negative individuals)
- will otherwise lead to fatal hypersensitivity syndrome

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10
Q

Which NRTIs can be taken during pregnancy?

A
  1. Emtricitabine
  2. Tenofovir
  • these 2 are Cat B
  • rest of NRTI drugs are Cat C
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11
Q

MOA of NRTIs?

A
  • NRTIs are analogs of native ribosides, but lack a 3’-OH group => leads to chain termination
  • as 3’,5’- phosphodiester bond between incoming nucleoside triphosphate & growing DNA chain cannot be formed
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12
Q

MOA of integrase inhibitors

A
  • prevents integration of viral DNA into host genome
  • by binding to the catalytic site of the HIV integrase enzyme
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13
Q

[T/F] Integrase inhibitor is active against both HIV-1 & HIV-2

A

True

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14
Q

Administration of integrase inhibitors (INSTI)?

A

Oral, tablets

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15
Q

Administration of NRTIs?

A

Oral

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16
Q

Which is the preferred INSTI for pregnant ppl?

A

Dolutegravir
(as of 2023)

17
Q

What is Ritonavir?

A

Pharmacokinetic(PK) booster
- not to be mistaken as a protease inhibitor
- inhibitory effect on CYP450 enzymes => extends shelf life of protease inhibitors cuz all PIs are substrates for CYP450

18
Q

MOA of Protease inhibitors

A
  • inhibits proteases that cleave the long polypeptides into smaller fragments => prevents new viral particles from maturing & becoming infectious
19
Q

Most of the HIV population is of which variant?

A

95% is due to HIV-1

20
Q

What are some issues with the usage of Proteins Inhibitors (PIs)?

A
  1. DDIs
  2. Lots of adverse effects
  3. Easy development of drug resistance when used ALONE
  4. Poor patient compliance cuz high no. of capsules req
21
Q

Why do PIs have lots of DDIs?

A
  • not only substrates for CYP450 but potent inhibitors of CYP450 isoenzymes
  • hepatic metabolism is extensive
22
Q

List out the drugs (ABs, antifungals and antivirals) that interfere w CYP450.

A
  1. Macrolides
  2. Azoles
  3. Protease Inhibitors
23
Q

What is Cobicistat?

A

PK enhancer of PIs
- inhibits CYP450 3A
- used PIs (Elvitegravir, Atanavir)

24
Q

What are NNRTIs useful against?
(non-nucleoside reverse transcriptase inhibitor)

A

Only effective against HIV-1
-highly selective, non-competitive inhibitor of HIV-1
(binds to other site that is not the active site)

25
Q

What is Efavirenz?

A

NNRTI

26
Q

What is a drawback of NNRTIs?

A
  • low genetic barrier to resistance
    -HIV becomes resistant to it quickly
    thus, shd nvr be added as a sole agent to a failing regimen
27
Q

Administration of NNRTI?

A

Oral
- bioavail increased w high fat foods -> more side effects

28
Q

What is a common combination of drugs for PrEP? (Pre-exposure prophylaxis)

A

Tenofovir & Emtricitabine (both NRTIs)
- sold under name Truvada
- daily use n continue till 1 month after last possible exposure
- requires high compliance
- highly effective in preventing HIV in HIV neg pxs from getting HIV

29
Q

What is PrEP & PEP?

A

Pre-exposure prophylaxis & Post exposure prophylaxis (for HIV)

30
Q

What is Acyclovir used for?

A
  • antiherpetic therapeutic agent
  • useful against HSV types 1 & 2, VZV, EBV
31
Q

What is Valacyclovir?

A
  • pro-drug of Acyclovir
  • greater oral bioavailibility than acyclovir
  • can be dosed less frequently
  • but more ex
32
Q

Can Acyclovir be used through pregnancy?

A

Yes, Cat B

33
Q

What is Gancyclovir used for?

A

Has inhibitory activity against all herpesviruses
- especially active against CMV

34
Q

MOA of Acyclovir and Gancyclovir?

A

Inhibits viral DNA synthesis.
- both are acyclic guanine nucleoside analogs

35
Q

What is the first line tx drug for CMV?

A

Gancyclovir

36
Q

Can Gancyclovir be used through pregnancy?

A

Cat C

37
Q

Which NRTI can cause osteomalacia as an adverse effect?

A

Tenofovir

38
Q

Which NRTI can cause inreased risk of cardiovascular disease & fatal hypersensitivity syndrome?

A

Abacavir

39
Q

Which NRTI can cause myelosuppression - anemia & neutropenia as a side effect?

A

Zidovudine