Antivirals, Antiretrovirals, and Antifungal Medications
Objectives
1. Describe how antiviral, antiretroviral, and antifungal medications work.
3. Outline Standard Precautions the nurse takes in limiting exposure to AIDS. (Review material in Chapter 10.)
Key Terms
acquired immune deficiency syndrome (AIDS) (ā-KWĪ-ĕrd ĬM-ū-nō-dē-FĬSH-ĭn-sē, p. 189)
antifungal medications (ăn-tī-FŬN-găl, p. 196)
antiretrovirals (ăn-tī-RĔT-rō-vī-rălz, p. 191)
human immunodeficiency virus (HIV) (ĬM-ū-nō-dē-FĬSH-ĭn-sē, p. 190)
mycotic infections (mī-KŎT-ĭk, p. 196)
opportunistic infections (ŏp-ŏr-TŪN-ĭst-ĭk, p. 193)
retrovirus (RĔT-rō-vī-rŭs, p. 190)
virions (VĪ-rē-ŭnz, p. 190)
Overview
http://evolve.elsevier.com/Edmunds/LPN/
Antiviral and antiretroviral drugs have two basic uses: (1) They treat a variety of common conditions caused by different viruses. These include viruses that cause herpes zoster, herpes simplex, genital herpes, varicella, and some influenza infections. Some antiviral medications are helpful in treating patients with cytomegalovirus retinitis. (2) More specialized antiviral products are used in treating the immunocompromised patient with human immunodeficiency virus (HIV) infection or for adults and children at risk for developing HIV and acquired immune deficiency syndrome (AIDs). They do not cure HIV or AIDS but they do help many patients live longer by acting to stop the production of new retroviruses by interfering with the ability of the retrovirus to replicate (reproduce).
Antivirals
Overview
A virus is a small infectious agent that can replicate only inside the living cells of organisms. They cannot survive without finding a host in which they may metabolize or make chemicals, grow, and reproduce. Viral infections are not suppressed by antibiotics. Antivirals interfere with the ability of the virus to carry out these reproductive functions.
Action and Uses
Many individuals have times when their body is not as strong at fighting infection as at other times or have low immunity. Individuals who once had varicella (chickenpox) still have the virus in their bodies. When immunity is low, patients have a greater chance of developing herpes infections from these usually quiet viruses that remained behind from the chicken pox. We now have some medications that are helpful in reducing the effects of some types of viral infections, such as herpes or influenza. Most common antiviral drugs may therefore be classed as either antiherpes, antiinfluenza, or neuraminidase inhibitors.
Antiviral drugs must enter the infected cell and act at the site of infection to be effective. The drugs often act in a very specific manner—they stop the virus from growing, but cannot kill it.
Antivirals used for herpes simplex or zoster are effective for short-term treatment, long-term suppression, and treatment of recurrence. Treatment of acute infection does not eliminate the chronic infection, which lies dormant. Resistance to the action of the drug may develop quickly.
Resistance to the antiinfluenza drugs amantadine and rimantadine has made them largely ineffective for the treatment of influenza. Neuraminidase products are effective against most strains of influenza A and B but the product may not always be available. With concerns about Avian flu, the government has stockpiled more of these products. Zanamivir is an antiviral product that must be given by inhalation.
Adverse Reactions
Many of these antiviral drugs are given topically and may have few recognized side or adverse effects. Some of the drugs are quite new, and information about adverse effects is still being collected. All health care personnel involved with giving these drugs must read the latest product information before administering these products.
Drug Interactions
Antivirals may also have drug interactions, often with products not usually involved in drug reactions. If giving antivirals, the nurse must read carefully about each of these products to determine if it can be given safely to the patient.
Nursing Implications and Patient Teaching
n Assessment
Understand clearly why the product is being ordered and what the physician or other health care provider hopes to accomplish with the drug plan. Learn all about the patient’s history. Know the precautions or contraindications. What conditions exist that may help or hurt the patient’s ability to take antiviral medicines as prescribed?
n Diagnosis
Identify other problems this patient has that might limit the effectiveness of treatment. Because antivirals only lessen symptoms and cannot cure disease, the same viral infection often occurs many times, and patients may need education, comfort, and basic teaching about how to reduce pain, itching, or discharge. These patients often experience weakness and muscle wasting. Ask questions such as: Do they have adequate nutrition? Can they afford the medicine? Will they be compliant?
n Planning
More information about antiviral medications is available every day. Review the latest information from the package inserts before giving these products.
n Implementation
Several of these products have special storage requirements or instructions for mixing. Read the latest information to administer these products correctly.
Specific information about these products is given in Table 13-1.
Table 13-1
| Antiherpes Drugs | ||
| GENERIC NAME | TRADE NAME | COMMENTS |
| acyclovir | Zovirax | For initial and recurrent mucosal and cutaneous HSV-1, HSV-2, and varicella-zoster infections in immunocompromised individuals. Also for severe acute and recurrent genital herpes in patients not immunocompromised. May be used for acute treatment of herpes zoster and chickenpox lesions. Initial parenteral infusion followed by oral therapy. Dosage depends on condition, acuity, and severity. |
| famciclovir | Famvir | For acute herpes zoster and recurrent genital herpes. |
| penciclovir | Denavir | Requires prescription but may move to OTC. Used in treatment of herpes labialis, herpes simplex. |
| valacyclovir HCl | Valtrex | For herpes zoster and recurrent genital herpes. |
| Antiinfluenza Drugs | ||
| amantadine HCl | Symmetrel | For prophylaxis of influenza A virus respiratory tract illnesses in patients at high risk because of underlying disease. |
| rimantadine | Flumadine | For prophylaxis and treatment of illnesses caused by various strains of influenza virus. In children, used as prophylaxis against influenza A virus. |
| Neuraminidase Inhibitors | ||
| oseltamivir phosphate | Tamiflu | For treatment of uncomplicated acute illness from influenza in patients older than 1 yr who have been symptomatic for more than 2 days or for prophylaxis for people older than 13 yr. |
| zanamivir | Relenza | Treatment of uncomplicated acute illness from influenza A and B in adults and children older than 7 years who have been symptomatic for more than 2 days. |
| Other Antivirals | ||
| cidofovir | Vistide | Used in CMV retinitis in patients with AIDS. |
| Given as IV infusion over 1 hr. Often given with probenecid. | ||
| foscarnet Na | Foscavir | For CMV retinitis and HSV infections. |
| ganciclovir | Cytovene | For CMV retinitis and infection in AIDS patients. Begun with parenteral therapy and followed with oral tablets. Watch for granulocytopenia and thrombocytopenia. |
| ribavirin | Virazole | For severe lower respiratory tract infections in hospitalized infants and young children with severe infections from RSV. Powder for aerosol administration only. |
n Evaluation
Watch the patient for signs of improvement in symptoms. Watch particularly for signs of toxicity or adverse effects that are specific to the medication taken.
n Patient and Family Teaching
Tell the patient and family the following:
• This medication is usually able to reduce or suppress symptoms, but it does not cure disease.
• The patient should be careful to follow any specific storage instructions for the medication.
The health care provider should work with pregnant patients to admit them to the national Antiretroviral Registry. This registry is the only project to evaluate first-trimester as well as late-pregnancy exposure to antiretroviral medications. Patient confidentiality is protected. Information obtained through this registry is used to learn how to weigh the risks and benefits of treatment for pregnant women and their fetuses.
Antiretroviral Agents
Overview
Acquired immune deficiency syndrome (AIDS) is a disease that causes a breakdown in the immune system, leaving the patient unable to fight infection. Because many people who develop AIDS die, it is one of the most frightening diseases. More than 98% of individuals who develop the most severe form of the disease die within 5 years of diagnosis. In some cases, advances in treatment have prolonged the lives of patients who can get the needed medications for as long as 35 years.
AIDS is a viral disease that arose in central Africa in the 1950s but is now found throughout the world. In the United States, the groups at highest risk for developing AIDS include homosexual and bisexual men, although the fastest growing group to develop AIDS is heterosexual women. Intravenous drug abusers, people in prison, female sexual partners of people in AIDS risk groups, and children born to mothers at risk of being HIV positive make up the other groups of people most likely to get AIDS. Minorities are overrepresented among the people who get AIDS. Recipients of blood products or of semen for artificial insemination also have developed AIDS. Because AIDS is an epidemic with a high mortality rate, it is important to understand what role medications play in slowing the advance of this disease and treating the other diseases that may result from the patient’s reduced immunity.
AIDS is caused by a retrovirus currently named human immunodeficiency virus (HIV). Retroviruses are viruses that contain ribonucleic acid (RNA) rather than deoxyribonucleic acid (DNA) as their genetic material. The HIV attaches to the CD4 protein with the help of coreceptors (CXCR4 or CCR5) found on helper T lymphocytes and other cells such as macrophages and dendritic cells. The HIV then fuses its membrane with that of the host cell and inserts its genetic material into the cytoplasm. The viral genetic material is then transcribed into double-stranded DNA called proviral DNA. The HIV enzyme reverse transcriptase is responsible for creating proviral DNA from viral RNA. Once produced, this DNA often becomes integrated into the chromosomal DNA of the host cell. The HIV DNA is then able to use the host cell’s genetic machinery to create new HIV RNA genetic material and messenger RNA. The messenger RNA codes for the development of HIV polyproteins, which must be cleaved, or separated, into individual proteins by the HIV enzyme protease for infectious virions (rudimentary virus particles) to be produced. Once this occurs, new virions are assembled; these bud from the host cell’s membrane and are able to infect new cells. This process is demonstrated in Figure 13-1
. Antiretrovirals are an important group of drugs that slow the growth or prevent the duplication of retroviruses; they are used to limit the advance of HIV and AIDS.
Research and clinical drug trials continue to make changes in what we know about AIDS. This will affect what drugs we use to treat AIDS patients and how we use them. Use only the most current information about these medications and their use in HIV-positive patients.
Action
By interfering with the ability of a retrovirus to reproduce, or replicate, antiretroviral agents act to stop more retroviruses from being made. At present, there are a wide variety of antiretrovirals in clinical use with other products in development. These types include:
