Anti-Virals

Question 1

Influenza vaccination schedule for 2 to 8 year olds

Answer 1

2 vaccinations spaced 1 month apart

• prime
• boost

Question 2

Influenza surface proteins

Answer 2

H - hemagglutinin (bind epithelial cells = Infectivity)

N - neuraminidase = (virons bud off = communicability/spread)

Question 3

Antigenic drift vs. Antigenic shift

Answer 3

Antigenic drift = yearly mutations in surface antigens requiring new vaccine and new antibodies

Ex. Covid XBB
Ex. yearly flu vaccination due to mutation of H and N

Antigenic shift = host becomes infected with two forms of the virus from different species

Ex. H1N1

Question 4

Oseltamivir mechanism of action

Answer 4

Neuraminidase inhibitor
prevents the virus from budding off and spreading / communicability

Used for prophylaxis and treatment

Question 5

List the Neuraminidase inhibitors

Answer 5

Oseltamivir

Zanamivir

Question 6

Indications for Oseltamivir and Zanamivir

Answer 6

Prophylaxis
- can be taken consecutively in immunocompromised patients to bridge gap to vaccination

Treatment
- start as soon as possible, no later than 48 hours

Question 7

SE Oseltamivir

Answer 7

Renal dose adjustment required

Question 8

SE and contraindications of Zanamivir

Answer 8

• Do not give to people with respiratory disease (asthma, COPD, etc.)
• Can cause bronchospasm, respiratory decline, and death

Question 9

Oseltamivir and Zanamivir drug interactions

Answer 9

Stop 48 hours before flu vaccination

If taking and vaccination given, will need to be re-vaccinated

wait 2 weeks before re-starting after the vaccination

Question 10

Age for prescription of Oseltamivir

Answer 10

> 1 year
Safe in preganncy

Question 11

Age for prescribing of Zanamivir

Answer 11

> 5 years of age (prophylaxis)
7 years of age (treatment)

*Inhaled, have to be able to coordinate administration

Contraindicated in respiratory diseases

Question 12

Age for prescribing flu vaccination

Answer 12

LAIV >/= 2 years
No pregnancy
less effective as age increases
no immunocompromised patients

IIV > 6 months of age
Safe in pregnancy

Question 13

Acyclovir Spectrum

Answer 13

Herpes Simplex Virus (HSV) > varicella zoster virus (VZV) > cytomegalovirus (CMV)

Question 14

Acyclovir Mechanism of action

Answer 14

activated by the viral thymidine kinase (virus specific)

Converted into GTP (guanosine tri phosphate)

NUCLEOSIDE ANALOG

incorporated into the growing DNA by viral DNA polymerase

1. halt DNA strand growth
2. inhibit DNA polymerase

Question 15

Acyclovir SE

Answer 15

Devoid of systemic SE

Drink a lot of water - renally cleared

Local burning and stinging

Question 16

Prescription age for Acyclovir

Answer 16

3 months of age

Question 17

Prescription age for valacyclovir

Answer 17

2 years

Question 18

Pregnancy and acyclovir and valacyclovir

Answer 18

Safe in pregnancy
Should not breast feed

Prescribed in third trimester to prevent infection and transmission during delivery

Question 19

Elderly and Acyclovir and Valacyclovir

Answer 19

Renal dose adjustment

Increased risk for renal damage and CNS effects (seizures, tremors)

Question 20

Oral bioavailability of acyclovir vs. valacyclovir

Answer 20

30 % vs. 50%

Question 21

Valacyclovir mechanism of action

Answer 21

Prodrug of acyclovir (NUCLEOSIDE ANALOG)

better bioavailability

Converted by liver

Thymidine kinase activates drug to form GTP

Stops DNA transcription and DNA polymerase

Question 22

SE and contraindication of valacyclovir

Answer 22

Liver and renal inflammation (crystalizes)

Contraindicated in immunocompromised

*Higher risk of TTP
Thrombotic thrombocytopenia purpura and HUS hemolytic uremic syndrome

Question 23

Drug monitoring Acyclovir / valacyclovir

Answer 23

CBC, WBC
- hemolytic uremic syndrome
- thrombotic thrombocytopenia purpura

LFTs
BUN, Creatinine clearance
- hepato and renal toxicity

Question 24

Treatment Chickenpox children

Answer 24

Prevention
Vaccination
15 months and 4 years

Treatment
No anti-viral

Question 25

Treatment Chickenpox adults

Answer 25

Anti-viral therapy within 72 hours
Ex. Valacyclovir

Question 26

Treatment Shingles adults

Answer 26

Anti-viral therapy within 72 hours

Vaccination 1 year post infection (MI/Stroke risk if < 12 months)
65 years to 71 years
2 vaccinations 2-6 months apart

Question 27

Treatment Chickenpox exposure pregnancy / neonate

Answer 27

Varicella immunoglobulin

pregnant adult: valacyclovir or acyclovir IV

neonate (> 2 months): can have acyclovir IV

Question 28

Varicella or herpes zooster infection near eye

Answer 28

Medical emergency, refer to ER and opthalmology

*Retina/optic nerve/vision loss risk