CHAPTER 36
DRUGS FOR VIRAL INFECTIONS
LEARNING OUTCOME 1
Describe the major structures of viruses.
Concepts
Viruses are nonliving agents that infect bacteria, plants, and animals. A virus is an intracellular parasite and
must be in a host cell to replicate and cause infection. A mature infective particle is called a virion. Viruses are
intracellular parasites that must be inside a host to cause infection. Viruses are primitive structures, surrounded
by a capsid (protein coat) and containing a few dozen genes. These genes are either ribonucleic acid (RNA) or
deoxyribonucleic acid (DNA). DNA contains information needed for replication. (Figure 36.1 illustrates the
structure of HIV.)
LEARNING OUTCOME 2
Identify viral infections that benefit from pharmacotherapy.
Concepts
Most viral infections are self-limiting and require no pharmacotherapy; for example, the rhinovirus that causes
the common cold. Some viruses cause serious disease and require aggressive therapy. For example, HIV is fatal
if left untreated. Another example, herpesviruses can cause significant pain and disability if left untreated.
Antiviral therapy is challenging for several reasons. Viruses mutate rapidly, and the drug becomes ineffective. It
is difficult for the drug to find the virus without injuring normal cells. Also, each antiviral drug is specific to one
particular virus.
LEARNING OUTCOME 3
Explain the purpose and expected outcomes of HIV pharmacotherapy.
Concepts
1. HIV targets the CD4 receptor on the T4 lymphocyte, using reverse transcriptase to make viral DNA from
RNA. Virions bud from the host cell, and the enzyme protease enables the virion to infect other T4
lymphocytes. The result is gradual destruction of the immune system. HIV is called a “retrovirus” because
of this reverse synthesis. (Figure 36.2 illustrates the replication cycle.)
2. Antiretroviral drugs used in the treatment of HIV-AIDS do not cure the disease, but they do help many
patients to live symptom-free longer. New drugs for this disease have been developed, and rates of
transmission from mother to newborn have been reduced. There has been a 70% decline in the death rate in
the United States, but in African nations the incidence of HIV infections is still very high.
3. The latent phases of HIV occur when the virus lies dormant, and people are often unaware they have
HIV. Once the diagnosis is confirmed, a decision about starting or delaying treatment must be made.
The current protocol is to defer treatment in asymptomatic adults who have CD4 counts above 350
cells/mcL. Therapy is initiated when CD4 is under 200 cells/mcL or when symptoms appear.
Therapeutic goals are to reduce HIV RNA load in the blood to an undetectable level or less than 50
Adams
Ch 36-1
copies/mL; an increased lifespan; a higher quality of life; and decreased risk of transmi ssion from
mother to child. Pharmacotherapy may be initiated in the acute (symptomatic) or chronic
(asymptomatic) phase of HIV infection.
LEARNING OUTCOME 4
Explain the advantages of HAART in the pharmacotherapy of HIV infection.
Concepts
Highly Active Antiretroviral Therapy (HAART) is the process of using drugs from five drug classes in various
combinations in the pharmacotherapy of HIV-AIDS. The five drug classes are nucleoside reverse transcriptase
inhibitor (NRTI), nonnucleoside reverse transcriptase inhibitor (NNRTI), protease inhibitor (PI), nucleotide
reverse transcriptase inhibitor (NtRTI), and fusion (entry) inhibitor. The nucleotide reverse transcriptase
inhibitors and the fusion inhibitors have been recently developed. Treatment failures are common with
antiretroviral therapy. Patients have nontolerance of adverse effects, they do not adhere to the complex regimen,
resistant strains can emerge, and genetic variability is a factor. Drug companies are responding to make
treatment simpler. Therapy is always changing, and health care practitioners need to stay current with the latest
treatments.
LEARNING OUTCOME 5
Describe the nurse’s role in the pharmacologic management of patients receiving antiretroviral and
antiviral drugs.
Concepts
1. The role of the nurse in the pharmacologic management of patients receiving antiretroviral and antiviral
drugs involves careful monitoring of a patient’s condition and providing education as it relates to the
prescribed drug treatment. Obtain baseline medical, surgical, and drug history; lifestyle and dietary habits,
including use of herbal or alternative therapies; and a detailed description of symptomology and current
therapies.
2. NRTI, NNRTI, and PI therapy: Although NRTIs, NNRTIs, and PIs act by different mechanisms, the
associated nursing care is similar. It is vital that the nurse establish a trusting, nonjudgmental relationship
with the patient and his or her lifestyle. Assess the patient’s understanding of the HIV disease process.
Assess for symptoms of HIV and any opportunistic infections. Monitor plasma HIV RNA (viral load)
assays, CD4 counts, complete blood count, liver and renal profiles, and blood- glucose levels throughout
antiretroviral therapy. Assess for bone-marrow suppression, liver toxicity, and Stevens–Johnson syndrome.
Advise the patient not to drive or perform hazardous activities until reactions to the medications are known.
Be aware of the many conditions and drugs that are problematic with antiretroviral therapy. Teach patients
how to practice blood and body-fluid precautions.
3. Antiviral Therapy: For patients with preexisting renal or hepatic disease, use the drugs with extreme
caution. Although many antiviral medications are listed as pregnancy categories B or C, judicious use is
still warranted during pregnancy. Emphasize compliance with antiviral therapy, such as taking the exact
amount around the clock even if sleep is interrupted. Although most antiviral drugs are well tolerated, some
cause GI distress and should be taken with food.
LEARNING OUTCOME 6
Ch 36-2
Adams
For each of the classes listed in Drugs at a Glance, know representative drugs, and explain the
mechanism of drug action, primary actions, and important adverse effects.
Concepts
1. Agents for HIV-AIDS—Nucleoside and Nucleotide Reverse Transcriptase Inhibitors.
Prototype drug: zidovudine (Retrovir, AZT). Mechanism of action: As the reverse transcriptase enzyme
begins to synthesize viral DNA, it mistakenly uses zidovudine as one of the nucleosides, thus creating a
defective DNA strand. Primary use: in combination with other antiretrovirals for both symptomatic and
asymptomatic HIV-infected patients, as well as for postexposure prophylaxis in HIV-exposed health care
workers. An important indication is to reduce the transmission rate of HIV from an HIV-positive mother to
her fetus. Adverse effects: severe toxicity to blood cells at high doses; anemia and neutropenia are common
and may limit therapy. Many patients experience anorexia, nausea, and diarrhea. Patients may report
fatigue and generalized weakness.
2. Agents for HIV-AIDS—Nonnucleoside Reverse Transcriptase Inhibitors.
Prototype drug: nevirapine (Viramune). Mechanism of action: to bind directly to reverse transcriptase,
disrupting the enzyme’s active site. Primary use: always used in combination with other antivirals in
treatment using HAART. Adverse effects: GI-related effects such as nausea, diarrhea, and abdominal pain
are experienced by some patients, and skin rashes, fever, and fatigue are frequent side effects.
3. Agents for HIV-AIDS—Protease Inhibitors.
Prototype drug: saquinavir mesylate (Fortovase, Invirase). Mechanism of action: to inhibit HIV protease.
Primary use: in combination with other antiretrovirals for HIV-infected patients. Adverse effects: nausea,
vomiting, dyspepsia, and diarrhea. General fatigue and headache are possible. (See Table 36.1.)
4. Agents for Herpesviruses.
Prototype drug: acyclovir (Zovirax). Mechanism of action: to prevent viral DNA synthesis. Primary use:
limited to the herpesviruses, for which it is a drug of choice. Adverse effects: nephrotoxicity when the
medication is given IV. (See Table 36.2.)
LEARNING OUTCOME 7
Use the nursing process to care for patients receiving drug therapy for viral infections.
Concepts
1. Patients receiving pharmacotherapy for HIV-AIDS—Assessment: Obtain a complete health history
including neurologic, cardiovascular, respiratory, hepatic or renal disease, and the possibility of pregnancy.
Obtain a drug history including allergies and possible drug interactions. Assess signs and symptoms of
current infection noting onset, duration, characteristics, presence or absence of fever or pain. Evaluate:
CBC, CD-4 count, HIV RNA assay, culture and sensitivity for any concurrent infections, hepatic and renal
function studies, lipid levels, serum amylase, and glucose. Assess patient’s ability to receive and understand
instruction. Assess for adverse effects.
2. Patients receiving pharmacotherapy for HIV-AIDS—Nursing diagnoses: Infection; Activity
Intolerance; Fatigue; Anxiety; Imbalanced Nutrition, Less than Body Requirements; Deficient Fluid
Volume; Diarrhea; Impaired Oral Mucus Membranes; Impaired Skin Integrity; Insomnia; Social Isolation;
Confusion (acute or chronic); Ineffective Therapeutic Regimen Management, related to complex medication
Adams
Ch 36-3
regimen and disease treatment; Deficient Knowledge, related to disease process, transmission, and drug
therapy; Hopelessness; Spiritual Distress; Risk for Injury, Risk for Falls, related to adverse drug effects or
disease; Risk for Caregiver Role Strain.
3. Patients receiving pharmacotherapy for HIV-AIDS—Planning: The patient will experience CD-4
counts and HIV RNA assays within acceptable limits, absence of signs and symptoms of concurrent
infection, ability to maintain ADLs; be free from or experience minimal adverse effects. Verbalize an
understanding of the drug’s use, adverse effects and required precautions. Demonstrate proper selfadministration of the medication (e.g., dose, timing, when to notify provider).
4. Patients receiving pharmacotherapy for HIV-AIDS— Implementation: Monitor vital signs,
especially temperature if fever is present. Monitor for symptoms of hypersensitivity and allergic
reactions. Continue to monitor periodic lab work: hepatic and renal function tests, CBC, CD -4 counts,
HIV RNA assays, lipid levels, serum amylase, culture and sensitivity if concurrent infections are
present, glucose. Monitor patient for signs of stomatitis. Continue to monitor for hepatic and renal,
toxicities (e.g., jaundice, RUQ pain, darkened urine, diminished urine output). Monitor for
dermatologic effects including red or purplish skin rash, blisters, or peeling skin, including oral
mucus membranes. Monitor for signs and symptoms of neurotoxicity (e.g., drowsiness, dizziness,
mental changes, insomnia, delusions, paresthesias, headache, changes in level of consciousness,
seizures). Monitor for signs and symptoms of blood dyscrasias (e.g., low -grade fevers, bleeding,
bruising, significant fatigue). Monitor for significant GI effects, including nausea, vomiting,
abdominal pain or cramping, and diarrhea. Administer drugs as per guidelines. Ensure adequate
nutrition and caloric intake. Monitor for symptoms of pancreatitis, including severe abdominal pain,
nausea, vomiting, and abdominal distension. Monitor blood glucose in patien ts taking antiretrovirals
Encourage infection control and good hygiene measures. Provide resources for medical and emotional
support. Instruct the patient and/or family in proper self- administration techniques followed by return
demonstration.
5. Patients receiving pharmacotherapy for HIV-AIDS— Evaluation: The patient will experience CD-4
counts and HIV-RNA assays within acceptable limits, absence of signs and symptoms of concurrent
infection, ability to maintain ADLs; be free from or experience minimal adverse effects. Verbalize an
understanding of the drug’s use, adverse effects, and required precautions. Demonstrate proper selfadministration of the medication (e.g., dose, timing, when to notify provider).
6. Patients receiving anti-viral pharmacotherapy for infections other than HIV-AIDS—Assessment:
Obtain a complete health history including neurologic, cardiovascular, respiratory, hepatic or renal
disease, and the possibility of pregnancy. Obtain a drug history including allergies and possible drug
interactions. Assess signs and symptoms of current infection noting onset, duration, characteristics,
presence or absence of fever or pain. Evaluate appropriate laboratory findings (e.g., CBC, hepatic and
renal function studies, viral cultures). Assess patient’s ability to receive and understand instruction.
Assess for adverse effects.
7. Patients receiving anti-viral pharmacotherapy for infections other than HIV-AIDS—Nursing
diagnoses: Impaired Oral Mucus Membranes; Impaired Skin Integrity; Fatigue; Activity Intolerance;
Social Isolation; Deficient Knowledge, related to disease process, transmission, and drug therapy; Risk for
Deficient Fluid Volume, related to disease process or adverse drug reactions; Risk for Imbalanced Nutrition,
Less than Body Requirements, related to disease process or adverse drug reactions.
8. Patients receiving anti-viral pharmacotherapy for infections other than HIV-AIDS—Planning:
The patient will experience therapeutic effects (e.g., diminished or absence of signs and symptoms of
infection, able to maintain nutrition and hydration, activity level increased); be free from or experience
minimal adverse effects. Verbalize an understanding of the drug’s use, adverse effects and required
precautions. Demonstrate proper self-administration of the medication (e.g., dose, timing, when to
Ch 36-4
Adams
notify provider).
9. Patients receiving anti-viral pharmacotherapy for infections other than HIV-AIDS—
Implementation: Monitor vital signs, especially temperature if fever is present. Monitor for symptoms
of hypersensitivity and allergic reactions. Continue to monitor periodic lab work: CBC, hepatic and
renal function tests, viral cultures. Continue to monitor for hepatic and renal, toxicities (e.g., jaundice,
RUQ pain, darkened urine, diminished urine output). Monitor for signs and symptoms of neurotoxicity,
particularly in patients on IV acyclovir (e.g., drowsiness, dizziness, tremors, headache, confusion,
changes in level of consciousness, seizures). Ensure patient safety and have patient rise slowly from
lying or sitting to standing. Monitor for signs and symptoms of blood dyscrasias (e.g., bleeding,
bruising, significant fatigue, increasing signs of infection). Monitor for significant GI effects, including
nausea, vomiting, and diarrhea. Ensure adequate nutrition and caloric intake. Encourage infection
control and good hygiene measures based on disease condition. Maintain hydration during acyclovir
therapy, providing pre-administration hydration if the drug is given IV. Monitor intake and output in the
hospitalized patient. Instruct patient and/or family in proper self-administration techniques followed by
return demonstration.
10. Patients receiving anti-viral pharmacotherapy for infections other than HIV-AIDS—Evaluation:
The patient will experience therapeutic effects (e.g., diminished or absence of signs and symptoms of
infection, able to maintain nutrition and hydration, activity level increased); be free from or experience
minimal adverse effects. Verbalize an understanding of the drug’s use, adverse effects and required
precautions. Demonstrate proper self-administration of the medication (e.g., dose, timing, when to
Websites
Adams
Ch 36-5