Ch. 40: Antiviral drugs Flashcards
Why are viruses called obligate intracellular parasites?
because viruses require a host in order to survive/replicate
Explain what is meant by fusion (regarding viruses)
occurs when the virions (DNA or RNA core of a virus) attach to host cells in preparation for infecting the cells
What are the 4 routes of entry of viruses?
inhalation through the respiratory tract
ingesting via the GIT
transplacentally from mother to infant
inoculation via skin or mucus membranes
Explain the difference between cytopathic effect, viral transformation, and latent infection that result from viral activity in a host cell
cytopathic effect: viral synthesis of nucleic acids and proteins which construct new virus which proceed to infect other cells and this cycle repeats
viral transformation: mutation of the host cell DNA or RNA
latent infection - virions remain inside host cells but do not actively replicate
Which of the following are specific immune responses? Non-specific?
phagocytosis
release of cytokines from WBC
antibodies
specific: antibodies
non-specific: phagocytosis and release of cytokines
What are the 2 categories of drugs that destroy virions?
disinfectants/virucides
immunoglobulins
Why are viral infections more difficult to eradicate?
viruses replicate inside host cells, so antiviral drugs must enter cells in order to disrupt viral replication
viruses replicate rapidly before any symptoms appear
What are the mechanisms in which most antiviral drugs work?
interfere with viral nucleic acid synthesis
prevent fusion of virion to host cell
What are the 2 major categories of antiviral drugs?
antiviral drugs - for medications used to treat viruses other than HIV
antiretroviral drugs - for treatment of HIV
Briefly describe the different herpes viruses.
Which require medications?
HSV-1 = perioral blisters
HSV-2 = genital herpes
HHV-3 = chicken pox and shingles (Varicella zoster virus = VZV)
HHV-4 = Epstein-Barr virus (EBV) - associated with mononucleosis and chronic fatigue syndrome
HHV-5 = cytomegalovirus (CMV)
HHV-6 and 7 not clinically significant but more likely to occur in immunocompromised patients
HHV-8 = Kaposi’s sarcoma herpesvirus - oncogenic virus to cause Kaposi’s sarcoma (AIDS-associated cancer)
Types 3-7 do not require medication except in the case of immunocompromised patients
Types 1-2 are treated with Rx medications
How are infants with HSV infections treated?
Cesarean section birth if mother has active genital herpes lesions
IV antivirals for babies born with HSV
Explain the relationship between chicken pox (varicella) and shingles (herpes zoster)
both are a result of varicella zoster virus (VZV)
chicken pox infection occurs in childhood –> virus is dormant in nerve ganglia for many years –> re-emerges as shingles in adulthood: painful lesions along dermatome of infected nerve
T/F: All active childhood infections of varicella (chicken pox) are treated with antiviral drugs
False: varicella infections are usually self-limiting and do not require antiviral drug therapy except in high risk ie. immunocompromised children
What is the risk of first-time varicella zoster virus infection to pregnant women?
VZV is teratogenic, especially during the first trimester
What drug is used to treat VZV?
acyclovir, valacyclovir, famciclovir
What is the mechanism of action of antiviral drugs?
block the activity of a polymerase enzyme –> catalyzes the synthesis of new viral genomes –> impaired viral replicaton
What is an adverse effect specific to Ribavirin?
anemia
therefore, it is CI’d for patients with pre-existing hemoglobinopathies such as sickle-cell anemia, and in patients with autimmune hepatitis
What is unique about retroviruses?
Retroviruses are RNA viruses, and use reverse transcriptase enzyme to synthesize DNA from RNA
What enzymes are involved in HIV replication?
Reverse transcriptase: synthesis of DNA from RNA
integrase: promotes integration of viral DNA into host cell DNA
protease: separates new viral RNA from viral protein molecules
Why is HIV retrovirus so difficult to “cure”?
because the virus is constantly mutating due to high number of errors when transcribing DNA from RNA (backwards process)
What are the 3 primary modes of infection with HIV?
sexual, parenteral, perinatal (in utero or during birth)
T/F: pregnant women infected with HIV are not given antiretrovirals until after birth because they have teratogenic effects on the fetus
False: prophylactic antiretroviral treatment of infected mothers reduces infection in infants by 2/3 and is not harmful to either mother or infant
T/F: Breast milk can transmit HIV to infants in 50% of cases
False: only 10-20% of cases
breastfeeding by infected mothers is CI’d in developed countries, but not in developing countries
What are the 4 stages of HIV/AIDS as per the WHO (2005)?
1: Asymptomatic infection
- after initial exposure to the virus, with persistent generalized lymphadenopathy (PGL)
2: early, general symptoms
- continued lymphadenopathy
- fever, rash, sore throat, night sweats, malaise, diarrhea, idiopathic thrombocytopenia, oral candidiasis, herpes zoster
- symptoms may not progress further for 1-10 years
3: moderate symptoms
- continued weight loss, chronic diarrhea, fever
- CD4+ count continues to drop and opportunistic infections begin
4: severe symptoms, often leading to death
= full blown AIDS
- major decline in immune function
- opportunistic infections: pneumocystic jirovecii pneumonia (PCP), CMV, HIV-associated neoplasms e.g. Kaposi’s sarcoma
What are some manifestations of HIV wasting syndrome
major weight loss
chronic diarrhea
more frequent or constant fever
chronic fatigue
What is meant when a patient is on Antiretroviral therapy (ART)?
a combination of at least 3 antiretroviral drugs to provide suppression of HIV and stop progression of AIDS
What are the mechanisms of action of antiretroviral drugs?
reverse transcriptase inhibitors (RTIs) block reverse transcriptase protease inhibitors inhibit protease retroviral enzyme --> inhibits breakup of chains of protein molecules fusion inhibitor (enfuvirtide) inhibits viral fusion integrase inhibitor (raltegravir) inhibits integrase - therefore, prevents integration of viral DNA into host cell DNA
When would a patient who has HIV need to alter his drug regimen?
if patient has major drug intolerance or resistance
if the patient’s HIV strain has evolved/mutated and the drug therapy is no longer effective
When is the HIV RNA viral load considered to be undetectable?
less than 50 copies/mL
What is the effect of ART on HIV patients with concurrent Hepatitis C virus (HCV)?
ART puts pharmacological strain on the liver so patients with both HIV and HCV have increased mortality due to liver disease
What is the major adverse effect of protease inhibitors?
lipid abnormalities, including lipodystrophy
What is a long-term adverse effect of ART?
bone demineralization –> osteoporosis
West Nile Virus (WNV) is transmitted to humans by ___________. WNV can progress to __________ and _____________. Prevention focuses on ___________.
mosquitoes
meningitis
encephalitis
mosquito control strategies
SARS is a ______________ virus and usually resolves on its own within _________.
coronavirus
3-4 weeks
Avian influenza can cause human infection, mostly following contact with ____________ or __________________ or ___________________.
infected birds
their secretions
excrement
H1N1 influenza virus is spread via ___________ or ______________.
coughing
sneezing
What are important nursing considerations about antivirals in the following forms:
oral
topical
IV
PO: should be given with meals to prevent GI upset
topical: should be applied with a finger cot or gloves to prevent autoinoculation
IV antivirals should be administered over 1 hour to avoid kidney damage and adequate hydration should be encouraged during and several hours after infusion to prevent drug-related crystalluria
What should the nurse do if a patient with HIV has signs and symptoms of opportunistic infections?
Contact the physician immediately
Which antivirals are prescribed to prevent/treat influenza A virus?
Which antiviral is for treatment of active influenza illness?
For prevention:
amantadine
oseltamivir (Tamiflu) - for influenza A or B
For active illness:
zanamivir (Relenza) - for influenza A or B
Acyclovir (Zovirax) is used to treat ______ and ________ virus
Herpes (oral and genital)
Varicella - for chicken pox
When teaching a patient who is taking acyclovir for genital herpes, which statement by the nurse is accurate?
a. acyclovir will eradicate the herpes virus
b. this drug will help the lesions to dry and crust over
c. this drug will prevent the spread of this virus to others
d. acyclovir does not reduce the frequency of genital herpes outbreaks
D
A patient who has been newly diagnosed with HIV has many questions about the effectiveness of drug therapy. After a teaching session, which statement by the patient reflects a need for more education?
a. there is no cure for HIV
b. these drugs will eventually eliminate the virus from my body
c. i will be monitored while on this medicine for adverse effects and improvements
d. these drugs do not eliminate HIV, but hopefully the amount of virus in my body will be reduced
B
During hospitalization for dehydration, an older adult patient is also receiving several doses of amantadine. Which statement explains the rationale for this medication therapy?
a. the drug is given IV to treat shingles
b. amantadine is used to prevent potential exposure to HIV
c. this medication is given prophylactically to prevent influenza A infection
d. amantadine works synergistically with antibiotics to reduce superinfections
C
