Clarithromycin Prophylaxis for MAC May Also Prevent PCP, Giardiasis

LISBON--Clarithromycin prophylaxis for Mycobacterium aviumcomplex (MAC) may provide additional benefits to AIDS patientsby preventing the development of common opportunistic infections,Mark Pierce, MD, said at the Third International Conference onthe Macrolides, Azalides, and Streptogra-mins, sponsored by AbbottLaboratories.

Clarithromycin (Biaxin), a macrolide antibiotic, is FDA approvedfor the prevention and treatment of MAC.

The findings are from a multicenter double-blind trial in which682 HIV-infected patients whose CD4 lymphocyte count was 100/mLor less were randomized to clarithromycin, 500 mg twice daily,or placebo, for the prevention of disseminated MAC infection,said Dr. Pierce, principal investigator of the trial and director,Infectious Diseases Clinic, Van-derbilt University School of Medicine.

In the study, patients were allowed to continue their currentprophylactic regimen for Pneumocystis carinii pneumonia(PCP). Eighteen patients (5.3%) on cla-rithromycin prophylaxishad a documented PCP episode vs 34 (10%) on placebo, a significantdifference.

Clarithromycin treatment was also associated with significantlyfewer episodes of community-acquired pneumonia: 24 episodes (7%)in patients receiving cla-rithromycin prophylaxis, compared with44 episodes (13%) in the placebo group.

Giardia lamblia, the bacterium responsible for giardiasis,was observed in only three patients (0.9%) randomized to clarithromycinvs 10 patients (2.9%) receiving placebo. Again, the differencewas significant. Clarithromycin-treated patients also experiencedfewer episodes of diarrhea than placebo-treated patients.

Clarithromycin was generally well tolerated, Dr. Pierce said.The only adverse event that occurred significantly more oftenin patients who received the mac-rolide was dysgeusia. The mostcommon side effects secondary to clarithromycin were abdominalpain (3.2%), diarrhea (2.9%), flatulence (1.3%), headache (1.6%),nausea (12.3%), rash (3.2%), dysgeusia (3.6%), and vomiting (7.5%).

Dr. Pierce said that he's not "100% convinced" thatclarithromycin actually prevents PCP, community-acquired pneumonia,and giardiasis in AIDS.

"AIDS patients treated with clarith-romycin may have hadfewer such infections because they didn't develop MAC and thereforestayed healthier longer," Dr. Pierce said. "While thedata do raise the possibility that clarithromycin is active againstthese infections, more research is needed to say that the relationshipis causal."