PI Perspective #26
December 1998 View PDF En
español
Advances in CMV Management:
Fomivirsen Approved
The Food and Drug Administration recently approved a new treatment
for cytomegalovirus (CMV) retinitis, an opportunistic infection
affecting people with advanced HIV disease. Left untreated, CMV
can lead to blindness.
Fomivirsen (Vitravene, formerly ISIS 2922) is given by injection
directly into the eye by an ophthalmologist (eye specialist) every
two or four weeks. The recommended dose is 330µg on days 1
and 15 during the initial phase of treatment (when CMV is still
spreading). It is then given once monthly during the maintenance
phase (when CMV is not actively spreading but requires therapy to
prevent it from reactivating). Studies show fomivirsen works equally
well in people with newly diagnosed CMV retinitis as in those receiving
other CMV therapies.
Since fomivirsen blocks CMV from replicating through a different
mechanism than that of other approved CMV retinitis therapies, people
who have developed resistance to other therapies may still benefit
from this drug. Because fomivirsen is administered directly into
the eye, it does not cause any systemic (throughout the body) side
effects.
However, in some studies, some people had retinal detachments.
In one study that employed a higher dose in people with newly diagnosed
CMV retinitis, some developed retinal stippling (spots in the retina)
which resulted in some loss of peripheral vision. The fact that
it works only locally in the eye also prevents the drug from suppressing
CMV infections elsewhere in the body, a limitation not shared by
most other treatments for CMV retinitis.
Though there have been no results directly comparing fomivirsen
with other approved therapies, the results from studies so far suggest
it is comparable in effectiveness to intravenous ganciclovir (Cytovene),
foscarnet (Foscavir) and cidofovir (Vistide) in suppressing and
preventing the recurrence of active CMV retinitis.
However, the ganciclovir implant (Vitrasert), which is surgically
implanted into the eye and slowly releases ganciclovir, has demonstrated
much longer lasting anti-CMV retinitis effects. Nonetheless, fomivirsen
is a welcome addition to the arsenal of anti-CMV therapies, especially
because of its ability to work after resistance develops to other
CMV therapies.
500mg Ganciclovir Capsule
A new 500mg capsule of ganciclovir (Cytovene) is now available for
use in the prevention and maintenance treatment of CMV disease.
Previously, oral ganciclovir was only available in 250mg capsules,
and when used for prevention or maintenance of CMV disease, required
12 capsules a day (1,000mg three times a day). This new 500mg capsule
will reduce by half the number of pills needed daily.
Oral ganciclovir is poorly absorbed into the body and therefore
is considered second-line therapy for the maintenance of CMV disease.
However, because all other systemic therapies for CMV are administered
intravenously (directly into the vein), many people opt for oral
ganciclovir because it does not require a surgically implanted catheter,
which is accompanied by a risk of serious bacterial infections.
Oral ganciclovir is also sometimes used for prevention of CMV disease
in people with severely compromised immune systems, but this use
of the drug remains controversial because of conflicting study results.
More importantly, the success of HAART today in partially restoring
immune function has diminished the need for preventive use.
A new formulation of oral ganciclovir, sometimes known as proganciclovir
or valganciclovir, is currently in studies. This new formulation
is so much better absorbed by the body that the sponsor hopes it
may eventually eliminate the need for intravenous therapy altogether.
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