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A combination of two antiviral drugs is more effective than eitherdrug alone for controlling recurrences of a blinding eye infectioncommon in people with AIDS, according to new clinical trial resultsfrom a federally-sponsored study.
In January’s Archives of Ophthalmology, researchersreport that daily intravenous administration of both foscarnet andganciclovir is a more effective way to treat repeat episodes ofcytomegalovirus (CMV) retinitis than treatment with either drug alone.
“This finding advances the treatment of chronic, destructiveeye infection that causes blindness if it is not controlled,”said Carl Kupfer, M.D., director of the National Eye Institute (NEI).The NEI, part of the National Institutes of Health (NIH), sponsoredthe CMV Retinitis Retreatment Trial. Additional NIH support wasprovided by the National Center for Research Resources and theNational Institute of Allergy and Infectious Diseases.
For patients who received both drugs, the CMV retinitis wascontrolled for about four months on average. Among those treated witheither foscarnet or ganciclovir alone, the eye infection recurred inone to two months on average. The combination treatment was associatedwith the least reduction in the field of vision, but visual acuity waspreserved equally well in all drug regimens tested.
However, researchers cautioned that the two-drug therapy takeslonger, because each drug has to be administered separately. Inaddition, the side effects associated with two-drug therapy may bemore difficult to tolerate than those with one drug alone. Also,because two drugs are required, the treatment is more expensive thanit would be if only one drug was used.
CMV retinitis is an infection of the retina, the light-sensingtissue that lines the back of the eye. The virus that causes it caninfect the eye, colon, lung, and other organs of people with AIDS orother diseases that result in weakened immune systems. According tosome studies, up to 40 percent of people with AIDS develop CMVretinitis, the most common cause of vision loss from the disease.
Currently, CMV retinitis is typically treated with twice-dailyintravenous infusion of either foscarnet or ganciclovir for two weeksfollowed by daily infusions which are usually continued for the restof the patient’s life. There also is an oral form of ganciclovirthat is available for long-term suppressive therapy. While the twodrugs work equally well for a first episode of CMV retinitis, nearlyall patients suffer a relapse of the retinitis at some point. Witheach relapse, more retinal cells are destroyed and more vision islost.
“Combination therapy was much better than treatmentwith either foscarnet or ganciclovir alone in controlling theretinitis progression,” said study chairman Douglas A. Jabs,M.D., of The Johns Hopkins University and Hospital. “However,combination therapy was more inconvenient, required two infusions, andwill be more expensive. But for those patients who have suffered arelapse of their retinitis and can tolerate combination therapy, itsimproved control of the retinitis offers distinct advantages.”
The CMV Retinitis Retreatment Trial involved 279 patients who hadalready had the eye infection and had been treated with eitherfoscarnet or ganciclovir, but experienced a relapse and needed furthertreatment. They were randomly assigned to foscarnet alone, gancicloviralone, or both drugs.
The trial was part of an ongoing clinical research project calledStudies of the Ocular complications of AIDS (SOCA).
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- Combination Foscarnet and Ganciclovir Therapy Vs. Monotherapy for The Treatment of Relapsed Cytomegalovirus Retinitis in Patients with AIDS. The Cytomegalovirus Retreatment Trial. The Studies of Ocular Complications of AIDS Research Group in Collaboration with The AIDS Clinical Trials Group. Arch Ophthalmol. 1996 Jan. PubMed