Antiviral Drugs - Pharmacology

Two groups of antivirals

1. Antivirals: Non HIV- given for infections caused by viruses other than HIV.

2. Antiretrovirals- HIV infection.

Viral infections

*Herpes simplex (HSV) 1*- oral herpes, cold sores.

*HSV 2*- genital herpes.

*HSV 3*- varicella zoster (VZV): chicken pox and shingles.

*Human herpesvirus 4*- Epstein Barr: mononucleosis.

*Human herpesvirus 5*- Cytomegalovirus (CMV).

*Influenza A and B.

Respiratory syncytial virus (RSV).

Hepatitis B and C.*

Non HIV Antivirals

Acyclovir (Zovirax)

Valcyclovir (Valtrex)

Amantadine (Symmetrel)

Ganciclovir (Cytovene)

Oseltamivir (Tamiflu) and Zanamivir (Relenza)

Ribavirin (Virazole)

Hepatitis Antivirals-

Simeprevir (Olysio)

Sofosbuvir (Solvaldi)

Telbivudine (Tyzeka)

Acyclovir (Zovirax)

Inhibits viral replication by suppressing the synthesis of viral DNA.

*Indications for use*- HSV 1 (oral herpes, cold sores), HSV 2 (genital herpes), HSV 3 (varicella zoster (VZV): chicken pox and shingles).

*Adverse effects*- IV- phlebitis, reversible nephrotoxicity, neurotoxicity (agitation, confusion, hallucinations). Oral/topical- N/V, local burning/tingling.

Oral, topical, IV.

Administer IV slowly and make sure patient is hydrated.

Valcyclovir (Valtrex)

Inhibits viral replication by suppressing the synthesis of viral DNA.

P.O.

*Indications for use*- HSV 1 (oral herpes, cold sores), HSV 2 (genital herpes), HSV 3 (varicella zoster (VZV): chicken pox and shingles). Helps with pain associated with infection.

*Adverse effects*- renal failure, thrombotic thrombocytopenia purpura (blood clotting in small vessels).

Amantadine (Symmetrel)

Effective for Influenza A. Can be given prophylactically to prevent flu.

CDC now does not recommend use for the flu (because of resistance built).

*Adverse effects*- insomnia, hypotension, dizziness.

Ganciclovir (Cytovene)

Suppresses viral DNA replication.

*Indications for use*- treat cytomegalovirus (CMV) infection in immunocompromised patients (organ transplants, chemotherapy).

*Adverse effects*- bone marrow depression- dose limiting effect! Reproductive toxicity (embryo, sperm), liver dysfunction.

IV, oral, occular gel and implant.

Oseltamivir (Tamiflu) and Zanamivir (Relenza)

Neuraminidase inhibitor (inhibits enzyme that is needed for viral replication).

*Indications for use*- Influenza A and B.

Makes flu less intense and shortens duration.

Treatment must begin early: no later than 2 days after onset of symptoms.

*Adverse effects*- N/V, psych problems (confusion, hallucination).

Ribavirin (Virazole)

Interferes with both RNA and DNA synthesis, thus protein synthesis and viral replication.

*Indications for use*- respiratory syncytial virus (RSV) (given inhalation), and hepatitis C (oral).

*Adverse effects*- Pregnancy category X (severe teratogenic effects!), anemia.

Simeprevir (Olysio)

Protease inhibitor for chronic Hepatitis C.

Used along with interferons: proteins that are antiviral and immunomodulating.

*Adverse effects*- photosensitivity, pregnancy X.

Sofosbuvir (Solvaldi)

RNA polymerase inhibitor.

Used for *Hepatitis C*.

Do not need to give with interferon!

*Adverse effects*- fatigue and headache.

Very expensive! $100,000 per patient!

Telbivudine (Tyzeka)

Used for *Hepatitis B*.

*Adverse effects-* fatigue, bone/muscle aching. Check renal function.

Nursing implications for Non HIV Antivirals

Used with caution in pregnant patients and patients with a history of renal disease.

Administer with food to decrease GI upset.

Monitor IV site for phlebitis (inflammation). Rotate IV sites.

Monitor for renal dysfunction by checking BUN and creatinine.

Antiretrovirals for HIV

HIV is the virus that causes AIDS.

HIV is a retrovirus.

Retroviruses are all RNA viruses. They use reverse transcriptase during replication.

HIV incorporates self into cell RNA \= replication of viral cells, not normal cells.

HIV binds to CD4 molecule on T4 helper cells \= cell destruction and decreased cellular immunity.

Types of Antiretrovirals for HIV

1. Non-nucleoside and/or nucleoside reverse transcriptase inhibitors.

2. Protease inhibitors.

3. Fusion inhibitors.

4. Chemokine receptor 5 CCR5 antagonist.

Therapeutic effect of all Antiretrovirals

Reduce the viral load, so the body's natural immune system can work.

Zidovudine (Retrovir)

Abbreviations are ZDV and azidothymidine AZT.

First drug available for HIV.

Combined with other drugs because resistance develops rapidly.

*Adverse effects-* bone marrow suppression (dose limiting effect), anxiety, headache, neuropathy, insomnia.

Indinavir (Crixivan)

Protease Inhibitor.

Helps to prevent HIV infection after known exposure.

Used in combination with other drugs.

Increases CD4 counts and reduces viral load.

*Adverse effects*- hyperglycemia/diabetes, hyperlipidemia, fat malabsorption, "fat pads".

What does CD4 level measure?

Your immune function.

Normal is 500-1500.

As virus gets worse, levels decrease.

As therapy is effective, levels increase.

Nursing implications for Antiretrovirals

Monitor CD4 levels.

Monitor CBC.

Check bleeding.

Assess for infections due to immunocompromised state.

Assess mental status.

*Response may take several weeks.*

Good nutrition is important.

Drugs suppress but do not cure.

Nursing implications for protease inhibitors (Indinavir)

Drink water to avoid kidney stones.

Assess liver function.

During treatment with zidovudine, the nurse needs to monitor for which potential adverse effect?

A. Retinitis

B. Deep vein thrombosis

C. Kaposi's sarcoma

D. Bone marrow suppression

D. Bone marrow suppression

After giving an injection to a patient with HIV infection, the nurse accidentally receives a needle stick from a too-full needle disposal box. Recommendations for occupational HIV exposure may include the use of which drug(s)?