132
P A R T 2
Chemotherapeutic agents
KEY POINTS
■■
Viruses are segments of RNA or DNA enclosed in a
protein coat.
■■
A virus must enter a human cell to survive, making it
difficult to treat without serious toxic effects for the
host.
■■
Antiviral drugs that prevent the viral replication of
respiratory viruses can be used to prevent or treat
influenza A or other respiratory viruses.
KEY POINTS
AGENTS FOR HERPES AND
CYTOMEGALOVIRUS
Herpes
viruses account for a broad range of conditions,
including cold sores, encephalitis, shingles and genital
infections.
Cytomegalovirus (CMV)
, although slightly
different from the herpes virus, can affect the eye, res-
piratory tract and liver and reacts to many of the same
drugs. Antiviral drugs used to combat these infections
include aciclovir (
Zovirax
), cidofovir (
Vistide
), fam-
ciclovir (
Famvir
), foscarnet (
Foscavir
), ganciclovir
(
Cymevene
), valaciclovir (
Shilova
,
Vaclovir
) and val-
ganciclovir (
Valcyte
). See Table 10.2.
Therapeutic actions and indications
Drugs that combat herpes and CMV inhibit viral DNA
replication by competing with viral substrates to form
shorter, non-effective DNA chains (see Figure 10.2).
This action prevents replication of the virus, but it has
little effect on the host cells of humans because human
cell DNA uses different substrates. These antiviral
agents are indicated for treatment of the DNA viruses
herpes simplex, herpes zoster and CMV. Research has
shown that they are very effective in immunocompro-
mised individuals, such as individuals with AIDS, those
taking immunosuppressants and those with multiple
infections. See Table 10.2 for usual indications for each
of these agents.
Evaluation
■
■
Monitor person’s response to the drug (prevention
of respiratory flu-like symptoms; alleviation of
flu-like symptoms).
■
■
Monitor for adverse effects (changes in orientation
and affect, blood pressure, urinary output).
■
■
Determine the effectiveness of the teaching plan
(person can name the drug, dosage, possible
adverse effects to watch for and specific measures
to help to avoid or minimise adverse effects).
■
■
Monitor the effectiveness of comfort and safety
measures and compliance with the regimen.
TABLE 10.2
DRUGS IN FOCUS Agents for herpes virus and cytomegalovirus (CMV)
Drug name
Dosage/route
Usual indications
aciclovir (Zovirax,
Lovir)
5–10 mg/kg q 8 hours or 200–800 mg
3–5 times daily for 5–10 days
Treatment of herpes virus infections
cidofovir (Vistide)
5 mg/kg IV (over 1 hour) once weekly for
2 weeks, then 5 mg/kg IV every 2 weeks
Treatment of CMV retinitis in people with
AIDS
famciclovir (Ezovir, Famvir,
Favic)
Herpes zoster: 250 mg PO q 8 hours for 7 days
Genital herpes: 125 mg b.d. PO for 5 days
Treatment of herpes virus infections such
as herpes zoster or shingles and for
recurrent episodes of genital herpes
foscarnet (Foscavir)
Adult: 40–60 mg/kg q 8–12 hours IV given as a
2-hour infusion
Paediatric: safety and efficacy not established
Treatment of CMV and aciclovir-resistant
mucocutaneous herpes simplex
infections in immunocompromised
individuals
ganciclovir (Cymevene,
Vitrasert)
Adult: 5 m/kg q 12 hours IV given over 1 hour
for 14–21 days, then over 1 hour daily 7 days/
week or 6 mg/kg per day for 5 days/week for
prophylaxis
Long-term treatment and prevention of
CMV infection
valaciclovir (Shilova,
Vaclovir)
Herpes zoster: 1 g PO t.d.s. for 7 days
Genital herpes: 500 mg b.d. PO for 5 days
Treatment of herpes zoster and recurrent
genital herpes; cold sores (herpes labialis)
valganciclovir (Valcyte)
900 mg PO b.d. for 21 days, then 900 mg PO
once a day for maintenance; reduce dose
with renal impairment
Treatment of CMV retinitis in people with
AIDS
