Lec 04 Antivirals Flashcards Preview

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Flashcards in Lec 04 Antivirals Deck (30)
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1
Q

The following are characteristics of viruses EXCEPT

A. small acellular infective agents
B. made of DNA, RNA, or both
C. has no metabolic machinery of its own
D. obligate intracellular parasites
E. NOTA
A

B.

Viruses are made of DNA or RNA, but not both.

2
Q

T/F

Most viruses have corresponding anti-viral agents.

A

F

3
Q

Enumerate complications of chickenpox.

A

viral pneumonia
superimposed bacterial infection
congenital limb anomalies

4
Q

Name the oral prodrug of the following antivirals.

acyclovir
penciclovir
ganciclovir

A

acyclovir - valacyclovir
penciclovir - famciclovir
ganciclovir - valganciclovir

5
Q

The following are true of acyclovir EXCEPT

A. It is an acyclic guanosine derivative.
B. It is phorsphorylated first by viral thymidine kinase.
C. The active form is a biphosphate.
D. The active form is a DNA chain terminator.
E. NOTA

A

C.

The active form is a triphosphate. It is phosphorylated first by viral thymidine kinase followed by two round of phosphorylation by cellular enzymes.

6
Q

T/F

Acyclovir has high activity for cytomegalovirus.

A

F

7
Q

Intravenous acyclovir is indicated in the following conditions EXCEPT

A. encephalitis
B. severe hepatitis
C. acute retinal necrosis syndrome
D. pediatric varicella lesions
E. NOTA
A

D. pediatric varicella lesions

Acyclovir is usually not needed in children with varicella lesions since they are usually mild.

8
Q

The following conditions lead to acyclovir resistance EXCEPT

A. absent production of viral thymidine kinase
B. partial decrease in production of viral thymidine kinase
C. altered viral thymidine kinase
D. altered viral DNA polymerase
E. NOTA

A

E. NOTA

9
Q

True of valacyclovir EXCEPT

A. It is an L-valyl ester of acyclovir.
B. It has oral and IV preparations.
C. It results in serum levels same with oral acyclovir.
D. It is excreted renally.
E. It has approximately the same half-life with acyclovir.

A

B. & C.

Valacyclovir is prepared in oral form only. Oral administration results in serum levels 3-5 times higher than oral acyclovir. This is because valacyclovir has higher bioavailability and is rapidly converted to acyclovir through first-pass metabolism.

10
Q

Enumerate adverse drug reactions of acyclovir and valacyclovir.

A
nausea and vomiting
diarrhea
thrombophlebitis (IV)
renal dysfunction
hematologic abnormalities
11
Q

This treatment is indicated for immunocompromised patients with mucocutaneous HSV lesions.

A

intravenous acyclovir

12
Q

True of ganciclovir EXCEPT.

A. It competes with guanosine triphosphate for incorporation.
B. It is a DNA chain terminator.
C. It is phosphorylated by viral phosphotransferase.
D. It has greater activity against CMV than acyclovir.
E. NOTA

A

B.

Ganciclovir is only a suppressor of viral DNA polymerase but not a DNA chain terminator.

13
Q

Give indications for ganciclovir and valganciclovir use.

A

CMV retinitis and congenital CMV

14
Q

T/F

Valganciclovir is a mixture of two diastereomers.

A

T

Valganciclovir also has higher bioavailability than ganciclovir.

15
Q

Enumerate the three steps of viral entry into host cell.

A
  1. Attachment
  2. Co-receptor Binding
  3. Fusion
16
Q

Identify the following. Give an answer per letter.

A. This enzyme converts viral RNA into DNA.
B. This enzyme incorporates viral DNA into host DNA.
C. This enzyme hydrolyzes viral proteins into smaller units to become functional.
D. These drugs act on A.
E. These drugs act on C.

A
A. reverse transcriptase
B. integrase
C. protease
D. NRTI / NNRTI
E. protease inhibitors
17
Q

These type of viral inhibitors are not available in the Philippines.

A

entry and fusion inhibitors

18
Q

Enumerate the adverse effects of non-nucleoside reverse transcriptase inhibitors (NRTIs)

A

lactic acidosis
hepatic steatosis
dyslipidemia

19
Q

This is the prototype NRTI drug.

A

zidovudine (ZDV) / azidothymidine (AZT)

20
Q

These two NRTIs are commonly recommended as they are well tolerated.

A

lamivudine (3TC)

tenofovir (TDF)

21
Q

Enumerate the contraindications for zidovudine.

A

concurrent stavudine

concurrent myelosuppressive agents (gaciclovir, ribavirin)

22
Q

True of non-nucleoside reverse transcriptase inhibitors (NNRTIs) EXCEPT

A. It is a noncompetitive inhibitor of reverse transcriptase.
B. It is metabolized by CYP3A4 and has many drug interactions.
C. It should not be administered with concurrent NRTIs.
D. Nevirapine (NVP) is the most recommended NNRTI.
E. NOTA

A

C.

NNRTIs may be administered concurrently with NRTIs since they have different mechanisms of action.

23
Q

True of nevirapine EXCEPT.

A. It has poor bioavailability.
B. It is teratogenic.
C. It is given as fixed dose.
D. It can be used as prophylaxis.
E. NOTA
A

A.

NVP has good bioavailability (90%)

24
Q

T/F

Protease inhibitors are also CYP3A4 inhibitors.

A

T

25
Q

T/F

Protease inhibitors has limited CNS penetration.

A

T

26
Q

Why is the combination of protease inhibitors lopinavir and ritonavir recommended?

A

The resultant drug-drug interactions increase the serum levels of both drugs.

27
Q

Enumerate adverse effects of lopinavir/ritonavir combination.

A
diarrhea
abdominal pain
nausea
hypertriglyceridemia
headache
increased liver enzymes
28
Q

This if the first integrase inhibitor to receive FDA approval.

A

raltegravir

29
Q

What is the mechanism of action of enfurvitide?

A

It is a fusion inhibitor which blocks the conformational change of GP41 that is necessary for the fusion of virions with the host cell.

30
Q

This test should be used to determine if the effectiveness of CCR5 inhibitor can be confounded by the co-receptor CXCR4.

A

trofile assay