Antivirals

Question 1

Viruses

Answer 1

Microorganisms that infect and replicate inside host cells
- Synthesize protein, DNA, and RNA

Viruses are difficult to kills because they live inside host cells - drug may have to also kill cells

Viral infections are often initially asymptomatic

Question 2

Host Defence

Answer 2

• A competent immune system is the best response to viral infections
• Will eliminate ro effectively estory virus replication
• Healthy immune system works synergistically with drugs to eliminate or suppress viral activity

Question 3

Immunocompromised Patients

Answer 3

Have frequent viral infections (cancer patients, transplant patients, and AIDS patients.

Question 4

Antiretroviral Drugs

Answer 4

Used to treat infections caused by HIV

Reverse transcriptase inhibitors (RTI)
- Block the activity of the enzyme reverse transcriptase, preventing production of new DNA from viral RNA
Subclasses = Nucleoside RTI (NRTI), and Non-nucleoside RTI’s (NNRTI’s)

Protease inhibitors

Question 5

Human Immunodeficiency Virus

Answer 5

• HIV is a member of the retrovirus family

- Transmitted by sexual activity, IV drug use, and from mother to fetus

Question 6

Opportunistic Infections - HIV

Answer 6

Protozoal
- Toxoplasmosis of the brain

Fungal

• Candidiasis of the lungs, esophagus, and trachea
• Pneumocystis jirovecii pneumonia

Viral
- CMV (Cytomegalovirus), HSV (Herpes)

Bacterial

• Various mycobacterial infections
• Extrapulmonary tuberculosis

Opportunistic neoplasias
- Kaposi’s sarcoma

Question 7

NRTI’s

Answer 7

Zudovudine (AZT - AZidoThymidine)

Nucleoside Reverse Transcriptase Inhibitors

Major adverse effect
- Bone marrow suppression and can lead to anemia and neutropenia

Question 8

Protease Inhibitors

Answer 8

Ritonavir

Inhibits retroviral protease enzyme, preventing viral replication

Protein is not a host cell protein = good drug target

Question 9

Combination theory

Answer 9

Essential for HIV treatment
HAART - Highly active antiretroviral therapy
- Goal is to reduce HIV in plasma - viral load

Combinations

• 2 NRTIs and 1 NNRTI
• 2 NRTIs and 1/2 Protease inhibitors
• BIKTARVY (bictegravir/emtricitabine/tenofovir alafenamide) 1 tab treatment of HIV-1 infection

Pre-Exposure Prophylaxis (PrEP)

• Tenofovir and emtricitabine (2 rti combination)
• To prevent acquisition of HIV infection by uninfected persons

Question 10

Herpesvirus Group

Answer 10

Varicella zoster virus

• Chickenpox (varicella)
• Shingles (herpes zoster)

Herpes simplex viruses

• HSV-1 oral herpes
• HSV-2 genital herpes

Cytomegalovirus

Question 11

Neuraminidase Inhibitors

Answer 11

Prevents release of virus from host cell

• Oseltamivir (tamiflu) and *Zanamivir (Relenza)
• active against influenza A and B virus

Treatment should begin within 2 days of influenza symptom onset

Can be used prophylactically when vaccination isn’t possible

Question 12

Inhibitor of Viral Coast Disassembly

Answer 12

Amantadine
- moderate activity against influenza A
- none against influenza B
- 99% of viruses are not resistant
- can be used prophylactically when vaccine is not available
- can reduce recovery time when used therapeutically
Used in treatment of Parkinson’s

Adverse effects:
- CNS: insomnia, nervousness, lightheadedness

Question 13

Acyclovir (Zovirax)

Answer 13

DNA Polymerase Inhibitor

• Stops viral DNA synthesis
• Used for Herpes viruses
• Available in oral, topical, and parenteral forms

Question 14

Cytomegalovirus

Answer 14

CMV

• Member of herpesvirus family
• Can be asymptomatic, high risk in immunocompromised patients
• Spread by bodily fluids

Question 15

Ganciclovir

Answer 15

DNA Polymerase Inhibitor

• Used to treat CMV, can affect brain, eye, lung, GI tract
• Available in oral, parenteral forms

Question 16

Ribavirin

Answer 16

Synthetic nucleoside

• Used to treat respiratory syncytial virus (RSV)
• Orally or nasal inhalation