Antibiotic Found Effective Against AIDS Illness : Medicine: Inexpensive drug is easier to administer than the aerosol generally used to treat parasitic pneumonia. It also seems to prevent relapses.
A frequently prescribed antibiotic is proving more effective in preventing the most common life-threatening complication of AIDS than an aerosol medication that is both costly and cumbersome to administer, according to AIDS specialists.
The antibiotic--widely used to combat bacterial conditions such as ear and urinary tract infections--can be taken in tablet form and is substantially cheaper than aerosol pentamidine, which must be delivered by a special device operated by a respiratory therapist.
The finding is significant because it adds another drug to the treatments that can prolong the lives of individuals infected with the human immunodeficiency virus, which causes AIDS.
AIDS experts emphasized, however, that formal studies comparing aerosol pentamidine to the antibiotic trimethoprim/sulfamethoxazole--marketed under the brand names Bactrim and Septra--are still under way.
Nevertheless, they said, their own clinical experience indicates that the antibiotic seems to work better in staving off the onset of parasitic pneumocystis carinii pneumonia among infected individuals whose immune systems show signs of damage, as well as subsequent episodes among those who have already suffered an initial bout of the pneumonia.
Patients on aerosol pentamidine, they said, are still experiencing recurrences of the infection, including a condition known as disseminated pneumocystis, in which the parasite attacks organs outside the lungs. This has not happened with the antibiotic, they said.
“Many people are moving much more rapidly toward the oral prophylaxis, both because of cost and convenience and also because of a growing perception that aerosol pentamidine isn’t as good as we once thought,” said Dr. Paul Volberding, professor of medicine at UC San Francisco and director of the AIDS division at San Francisco General Hospital.
“There’s been quite a lot of talk about this,” Volberding said. “Physicians working with AIDS patients are comparing notes about how they’re treating different problems, and this has become a frequent topic of conversation.”
Nearly a year ago, aerosol pentamidine was hailed as a major therapeutic breakthrough in the prevention of pneumocystis , a parasitic infection that often is the first manifestation of AIDS and is a frequent killer of AIDS patients. The infection, which usually strikes the lungs, is fatal if left untreated.
Pentamidine and trimethoprim/sulfamethoxazole are already approved as treatments for the pneumocystis infection. But studies completed earlier this year found that pentamidine delivered in an aerosol form was extremely effective in preventing its onset.
Soon after the findings were released, it became standard practice to recommend monthly treatments with aerosol pentamidine for HIV-infected individuals whose immune systems had begun to show signs of deterioration as measured by levels of T4 helper cells, the white blood cells that are a primary target of the AIDS virus. Infected individuals with low T4 counts are considered at extremely high risk of developing pneumocystis .
It also became routine to use the aerosol drug to prevent further episodes in those who had already experienced their first bout of pneumocystis .
But AIDS activists and others complained that the drug, manufactured by Fujisawa USA (formerly LyphoMed Inc.) of Rosemont, Ill., was too expensive. The price varies widely, but a monthly treatment generally costs at least $150. Also, the therapy requires the use of a pressure-driven nebulizer, a device that reduces a liquid to a fine spray, operated by a trained respiratory therapist.
Even more important, researchers said, they began to notice that their patients were still suffering recurrences of pneumocystis, including those who were specifically trying to prevent a secondary episode.
“In those patients, we saw a rate of relapse approaching 25%,” said Dr. Margaret Fischel, a professor of medicine and AIDS specialist at the University of Miami. “We began to look for alternatives because, for a preventive agent, that is too high. It was very distressing.”
As a result, many doctors began giving their patients trimethoprim/sulfamethoxazole, and they have been extremely pleased with the results.
“The relapse rate has been virtually zero,” said Dr. Robert T. Schooley, an AIDS researcher who heads the infectious diseases division of the University of Colorado Health Sciences Center. “Unless there’s a problem with (trimethoprim/sulfamethoxazole), I’d use that first. If I were a patient with HIV infection, I’d certainly be asking my doctor about this.”
Researchers said that side effects of the antibiotic include allergic reactions--such as severe rash--and lower blood cell counts. However, researchers said that lower doses of the antibiotic can alleviate those problems in most cases and still achieve protection against pneumocystis.
“We have found that you can . . . overcome the problems,” Fischel said. “With lower doses, you can successfully treat everybody.”
Septra, which is manufactured by Burroughs Wellcome Co. of Research Triangle Park, N.C., and Bactrim, made by Hoffmann-La Roche Inc. of Nutley, N. J., cost patients about $35 to $40 a month. A generic version of the drug typically costs less than $10 a month.
The latest evidence also strengthens arguments for being tested for HIV infection, researchers said.
“This whole issue is important, because we can now predict the likelihood of pneumocystis even when somebody is asymptomatic,” Volberding said. “When I see somebody whose first evidence of AIDS is that he’s gotten pneumocystis, that’s a failure. That’s a failure on our part to get that person involved in (preventive) treatment.”
