3.14 Antivirals
Unlike the complex structure of fungi or protozoa, viral structure is simple. There are several subclasses of antiviral medications: antiherpes, antiinfluenza, antihepatitis, and antiretrovirals. Each subclass will be discussed in more detail below. See Figure 3.8[1] for images of viruses.
Subclass: Antiherpes
Mechanism of Action: Acyclovir causes termination of the DNA chain during the viral replication process. Acyclovir can be administered either topically or systemically, depending on the infection.[2]
Indications: Acyclovir (Zovirax) and its derivatives are frequently used for the treatment and prevention of herpes and varicella virus infections, including genital herpes, chicken pox, shingles, Epstein-Barr virus infections, and cytomegalovirus infections.
Nursing Considerations: Acyclovir use may result in nephrotoxicity.
Side Effects/Adverse Effects: Common side effects may include gastrointestinal distress. Additional adverse effects may include renal impairment and decreased seizure threshold.
Health Teaching & Health Promotion: Clients who are being treated with antiviral therapy should be instructed about the importance of medication compliance. They may also experience significant fatigue, so periods of rest should be encouraged.[3]
Subclass: Antiinfluenza
Mechanism of Action: Tamiflu prevents the release of virus from infected cells.
The influenza virus is one of the few RNA viruses that replicates in the nucleus of cells. Antivirals block the release stage. See Figure 3.9.[4]
Indications: Oseltamivir (Tamiflu) is used to target the influenza virus by blocking the release of the virus from the infected cells.
Nursing Considerations: This medication does not cure influenza but can decrease flu symptoms and shorten the duration of illness if taken within 48 hours of symptom onset. Clients are prescribed the medication for prophylaxis against infection, known exposure, or to lessen the course of the illness. If clients experience flu-like symptoms, it is critical that they start treatment within 48 hours of symptom onset.
Side Effects/Adverse Effects: Common side effects include GI upset. Adverse effects include serious skin hypersensitivity reactions or neuropsychiatric symptoms, especially in children. Use cautiously in clients with renal failure, chronic cardiac or respiratory diseases, or any medical condition that may require imminent hospitalization.
Health Teaching & Health Promotion: Clients who are being treated with antiviral therapy should be instructed about the importance of medication compliance. They may also experience significant fatigue, so periods of rest should be encouraged.[5]
Subclass: Antihepatitis
Mechanism of Action: Antihepatitis medications inhibit translation of viral mRNA into viral proteins. This action impedes the replication of the hepatitis virus.
Indications: Antihepatits medications like adefovir are used to treat chronic hepatitis and the hepatitis B virus and hepatitis C virus.
Nursing Considerations: The medication is used to maintain or improve liver function when active disease is present. Therapy is prolonged, typically greater than 1 year or indefinitely, based on the client’s status.
Side Effects/Adverse Effects: Adverse effects of antihepatitis medications include severe acute exacerbations of hepatitis B, nephrotoxicity, lactic acidosis, and severe hepatomegaly.
Health Teaching & Health Promotion: Clients receiving treatment for antihepatitis medications should also be offered HIV testing to ensure that they do not have an unrecognized or untreated HIV infection. Antihepatitis medications may promote resistance to antiretrovirals in clients with chronic Hepatitis B infection. Clients must understand that they should not stop taking medication unless directed by a health care provider. Monitor hepatic function several months after stopping therapy.
Subclass: Antiretrovirals
Viruses with complex life cycles, such as HIV, can be more difficult to treat. These types of viruses require the use of antiretroviral medications that block viral replication, often referred to as antiretroviral therapy (ART). (See Figure 3.10 to view the viral replication process of HIV.)[6] Additionally, antiretrovirals fall under the class of antiviral medications.
Mechanism of Action: Antiretrovirals impede virus replication.
Indications: Antiretrovirals such as lamivudine-zidovudine are used for the treatment of illnesses like HIV.
Nursing Considerations: Many antiretrovirals may impact renal function; therefore, the client’s urine output and renal labs should be monitored carefully for signs of decreased function.
Side Effects/Adverse Effects: Adverse side effects of antiretroviral medications include lactic acidosis and severe hepatomegaly. Clients should cease medication immediately if pancreatitis occurs.
Health Teaching & Health Promotion: Clients who are being treated with antiviral therapy should be instructed about the importance of antiretroviral compliance. They may also experience significant fatigue, so periods of rest should be encouraged.[7]
Now let’s take a closer look at the medication grids for the subclasses of antivirals in Tables 3.14a-d.[8]
Tables 3.14a Acyclovir Medication Grid
| Class/Subclass | Prototype/Generic | Nursing Considerations | Therapeutic Effects | Side/Adverse Effects |
|---|---|---|---|---|
| Antivirals: Antiherpes | acyclovir | Check for allergies
Route: PO, IV, or topical; do not give IM or subcutaneously Give with food if GI upset occurs IV: Give IV infusion over at least 1 hour to prevent renal tubular damage Use cautiously if renal impairment, neurological problems, or dehydration Start therapy as early as possible after signs or symptoms occur Encourage fluid intake Avoid sexual contact while genital lesions are present |
Drug is not a cure for herpes but improves signs and symptoms of herpes lesions if started early
Can be prescribed at lower doses for long-term for prevention of outbreaks |
GI distress
Monitor renal function in long-term use, especially if renal impairment Lowers seizure threshold |
Tables 3.14b Oseltamivir Medication Grid
| Class/Subclass | Prototype/Generic | Nursing Considerations | Therapeutic Effects | Side/Adverse Effects |
|---|---|---|---|---|
| Antivirals: Antiinfluenza Agents |
oseltamivir | Check for allergies
Route: PO Must be given within 48 hours of onset of symptoms Administer with food to avoid GI distress Does not replace need for annual influenza vaccination |
Reduce duration of influenza symptoms | GI distress
Serious skin/ hypersensitivity reactions; discontinue immediately Monitor for neuropsychiatric symptoms Use cautiously in clients with renal failure, chronic cardiac or respiratory diseases, or any medical condition that may require imminent hospitalization |
Tables 3.14c Adefovir Medication Grid
| Class/Subclass | Prototype/Generic | Nursing Considerations | Therapeutic Effects | Side/Adverse Effects |
|---|---|---|---|---|
| Antivirals: Antihepatitis Agents |
adefovir | Route: PO
Prolonged therapy (greater than 1 year or indefinitely) based on client status Offer HIV testing; may promote resistance to antiretrovirals in clients with chronic HBV infection who also have unrecognized or untreated HIV infection Do not stop taking medication unless directed. Monitor hepatic function several months after stopping therapy |
Maintain or improve liver function when active disease is present | Severe acute exacerbations of hepatitis B
Nephrotoxicity Lactic acidosis Severe hepatomegaly |
Tables 3.14d Lamuvadine-Zidovudine Medication Grid
| Class/Subclass | Prototype/Generic | Nursing Considerations | Therapeutic Effects | Side/Adverse Effects |
|---|---|---|---|---|
| Antivirals: Antiretrovirals Nucleoside–Nucleotide Reverse Transcriptase Inhibitors |
lamivudine- zidovudine | Check for allergies
Lamivudine used to treat HIV-1 infection contains a higher dose of the active ingredient than the lamivudine used to treat chronic HBV infection. Clients with HIV-1 infection should receive only dosing forms appropriate for HIV-1 treatment Use cautiously in clients with renal impairment Inform client that drug doesn’t cure HIV infection, that opportunistic infections and other complications of HIV infection may still occur, and that transmission of HIV to others through sexual contact or blood contamination is still possible. Taking these medications, along with practicing safer sex and making other lifestyle changes, may decrease the risk of transmitting (spreading) the HIV or hepatitis B virus to other people Teach clients to report symptoms of pancreatitis such as sudden abdominal pain, nausea, or yellowish tinge of the skin or eyes |
Decreases chance of developing acquired immunodeficiency syndrome (AIDS) and HIV-related illnesses such as serious infections or cancer | Lactic acidosis
Severe hepatomegaly Stop treatment immediately if pancreatitis |
Critical Thinking Activity 3.14
Using the above grid information, consider the following clinical scenario question:
A client is prescribed oseltamivir (Tamiflu) for influenza symptoms. The client states to the nurse, “I hope this medication works quickly! I have felt awful for the past five days!” What is the nurse’s next best response?
Note: Answers to the Critical Thinking activities can be found in the “Answer Key” section at the end of the book.
- “Unknown” by CNX OpenStax is licensed under CC BY 4.0. Access for free at https://openstax.org/books/microbiology/pages/1-3-types-of-microorganisms ↵
- This work is a derivative of Microbiology by OpenStax licensed under CC BY 4.0. Access for free at https://openstax.org/books/microbiology/pages/1-introduction ↵
- uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral ↵
- “Unknown” by CNX OpenStax is licensed under CC BY 4.0 Access for free at https://openstax.org/books/microbiology/pages/6-2-the-viral-life-cycle ↵
- uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral ↵
- This work is a derivative of “HIV Virus Replication Cycle” by NIAID is licensed under CC BY 2.0 ↵
- uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral ↵
- This work is a derivative of DailyMed by U.S. National Library of Medicine in the Public Domain. ↵