Varying Dosages of Rifabutin Affect White Blood Cell and Platelet Counts in Human Immunodeficiency Virus-Negative Patients Who Are Receiving Multidrug Regimens for Pulmonary Mycobacterium avium Complex Disease

• Published in: Clinical infectious diseases 1996-12, Vol.23 (6), p.1321-1322
• Main Authors: Griffith, David E., Brown, Barbara A., Wallace, Richard J.
• Format: Article
• Language: English
• Subjects: AIDS/HIV; Azithromycin - therapeutic use; Biological and medical sciences; Brief Reports; Clarithromycin - therapeutic use; Dosage; Dose-Response Relationship, Drug; Drug Therapy, Combination; Drug toxicity and drugs side effects treatment; Fungal infections; Fungal lung diseases; Hematologic diseases; HIV; Human immunodeficiency virus; Humans; Leukocyte Count - drug effects; Lung diseases; Lung Diseases - drug therapy; Medical sciences; Mycobacterium avium; Mycobacterium avium Complex; Mycobacterium avium-intracellulare Infection - drug therapy; Pharmacology. Drug treatments; Platelet Count - drug effects; Platelets; Pretreatment; Rifabutin - therapeutic use; Toxicity: blood; Viral diseases
• ISSN: 1058-4838; 1537-6591
• DOI: 10.1093/clinids/23.6.1321

We previously reported that adverse events occurred in 26 HIV-negative patients with pulmonary Mycobacterium avium complex (MAC) disease who were treated with high-dose rifabutin (600 mg/d) as part of multidrug regimens containing either daily doses of clarithromycin (15 patients) or azithromycin. The most frequently encountered adverse events were hematologic. Total WBC counts, granulocyte counts, and platelet counts declined in most of the patients studied. It is noteworthy that rifabutin affected WBC and platelet counts for a group of patients who were primarily taking azithromycin. Azithromycin, unlike clarithromycin, is not known to affect the hepatic cytochrome P-450 system; therefore, these hematologic abnormalities are not merely the result of a drug interaction. These hematologic effects should be anticipated when rifabutin-containing regimens are administered with or without clarithromycin or azithromycin, and WBC counts and platelet counts should be routinely monitored when the dosage of rifabutin is greater than or equal to 300 mg/d. The risk for developing these hematologic abnormalities appears to be greater when rifabutin is administered daily rather than three times a week.