RIF/PZA tryouts yield mostly good reviews
To quell GI complaints, some adjust PZA
Among the small numbers who’ve had time to try it out, the new regimen for short-course treatment of latent TB infection — two months of rifampin/pyrazinamide (RIF/PZA) — is drawing positive reviews from physicians and patients alike, albeit with some reservations.
Across Florida, about 30 HIV-positive patients have tried the two-month regimen, says David Ashkin, MD, the state’s TB control officer. "Over 80% have completed [the program], and with a minimal amount of toxicity," Ashkin says. "Of course we don’t have enough data to say anything yet about efficacy. But to my knowledge, no one’s dropped out because of side effects."
Among small samples of patients who’ve tried the new regimen in Massachusetts and Georgia, physicians report some side effects, which shouldn’t surprise anyone, experts say. "We expect side effects will be more frequent [than with six months of isoniazid], but there are ways to deal with that," says Rick O’Brien, MD, chief of the Research and Evaluation Branch of the Division of Tuberculosis Elimination at the Centers for Disease Control and Prevention. "One way is to use the lower end of the recommended dose of pyrazinamide."
Adjusting the dose did the trick in Atlanta, where providers decided RIF/PZA might be one way to get preventive therapy into a group of people whose most reliable source for health care turned out to be the city jail.
Jail inmates were surprisingly enthusiastic about trying out a two-month preventive regimen, says Naomi Bock, MD, MS, medical epidemiologist and clinical consultant for the Georgia Department of Health; and assistant professor in the department of medicine at Emory University in Atlanta. When they came down with stomachaches, she found that adjusting the dose of PZA downward fixed the problem. Completion rates so far aren’t as good as Bock had hoped, but not for reasons related to tolerability. (See related article, p. 41.)
Just letting patients know what they’re getting into — lots of pills, and maybe an upset stomach — will probably help them stay committed to the two-month regimen, contends O’Brien.
But in Massachusetts, Ed Nardell, MD, chief of pulmonary medicine at Cambridge Hospital and TB control officer for the Massachusetts Public Health Department, says patient education may be more complicated than such advice suggests.
A handful of patients in Massachusetts who tried short-course preventive therapy completed at rates that weren’t quite as good as rates for a bigger group, which chose six months of INH, says Nardell. (Of 15 Massachusetts patients who tried RIF/PZA, eight finished, and seven quit, for a completion rate of 53%; among the INH group, of 52 patients, 30 finished, and 22 didn’t, for a completion rate of 57%.)
The Massachusetts patients were all HIV-negative, as far as anyone knows, which invites comparison to the study of RIF/PZA by the CDC, which found that HIV-negative patients do not appear to tolerate the new regimen as well as their HIV-positive counterparts.
Perhaps HIV-positive patients are generally a more motivated bunch, Nardell surmises. "When you offer [regular HIV-negative patients] the choice, even though you warn them about possible side effects, what they really hear is the part about two months,’" he says. That may explain why at the first sign of discomfort, this group seems quick to fall by the wayside. (A patient survey suggested as much, with dropouts reporting only minor complaints.)
Still, Nardell plans to continue to keep offering his patients the choice. "It’s nice to be able to forget about age 35 because of course you only have to worry about that with isoniazid," he says. "That opens lots of doors."
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