C H A P T E R 1 0
Antiviral agents
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any of these drugs crosses the placenta or enters breast
milk. Peak effects of boceprevir occur in 2 hours and
for telaprevir in 4 to 5 hours. Telaprevir has a half-life
of 4.0 to 4.7 hours and boceprevir has a half-life of
3.4 hours.
Contraindications and cautions
These drugs are contraindicated with any known allergy
to the drugs and with breastfeeding because of potential
toxicity to the infant. Use caution when administering
these drugs to individuals with renal impairment and
severe liver disease and women who are pregnant.
Adverse effects
The adverse effects most frequently seen with these
drugs are headache, dizziness, nausea, diarrhoea and
elevated liver enzymes. Severe hepatomegaly with
steatosis, sometimes fatal, has been reported with
adefovir and telbivudine use. Lactic acidosis and renal
impairment have been reported with entecavir and
adefovir. A potential risk for hepatitis B exacerbation
could occur when the drugs are stopped. Therefore,
teach people the importance of not running out of their
drugs and use extreme caution when discontinuing
these drugs.
Common adverse effects for both boceprevir and
telaprevir include anaemia, pruritus and nervous system
disorders.
Clinically important drug–drug interactions
There is an increased risk of renal toxicity if these drugs
are taken with other nephrotoxic drugs. If such a combi-
nation is used, monitor the person closely. An evaluation
of risks versus benefits may be necessary if renal function
begins to deteriorate.
Prototype summary: Adefovir
Indications:
Treatment of chronic hepatitis B in
adults with evidence of active viral replication
and either evidence of persistent elevations in
alanine aminotransferase (ALT) and aspartate
aminotransferase (AST) or histologically active
disease.
Actions:
Inhibits hepatitis B virus reverse
transcriptase, causes DNA chain termination
and blocks viral replication.
Pharmacokinetics:
Route Onset
Peak
Duration
Oral
Rapid
0.6–4 hours Unknown
T
1/2
:
7.5 hours; excreted in the urine.
Adverse effects:
Headache, asthenia, nausea,
severe-to-fatal hepatomegaly with steatosis,
nephrotoxicity, lactic acidosis, exacerbation of
hepatitis B when discontinued.
TABLE 10.4
DRUGS IN FOCUS Anti-hepatitis B and C agents
Drug name
Dosage/route
Usual indications
Hepatitis B
adefovir (Hepsera)
Adult: 10 mg/day PO
Renal impairment:
CrCl 30–49 mL/min: 10 mg PO q 48 hours
CrCl 10–29 mL/min: 10 mg PO q 72 hours
Treatment of hepatitis B with evidence
of active viral replication and persistent
elevations in liver enzymes
entecavir (Baraclude)
Adults and children (≥16 years): 0.5 mg/day;
also receiving lamivudine: 1 mg/day
Reduce dose with renal impairment
Treatment of chronic hepatitis B in adults
with evidence of active viral replication
and persistent liver enzyme elevations
telbivudine (Sebivo)
Adults and children >16 years: 600 mg/day PO;
reduce dose with renal impairment
Treatment of chronic hepatitis B in
people >16 years with evidence of viral
replication and persistent liver enzyme
elevations
Hepatitis C
boceprevir (Victrelis)
Adult: 800 mg PO t.d.s.
Treatment of adults with chronic
hepatitis C in combination with
peginterferon alfa and ribavirin
telaprevir (Incivo)
Adult: 750 mg PO q 8 hours
Treatment of chronic hepatitis C in adults
with compensated liver disease
CrCl, creatinine clearance.
