Objective: To describe a case of acute hemolysis associated temporally with administration of trimethoprim/sulfamethoxazole (TMP/SMX) in a patient with AIDS, review the available literature on TMP/SMX-induced hemolytic anemia, and discuss possible drug- and disease-related factors that may have contributed to the episode of hemolysis.
Case summary: A precipitous decrease in red blood cell count, hemoglobin, and hematocrit occurred shortly after a black woman with AIDS received a single intravenous dose of TMP/SMX for Pneumocystis carinii pneumonia. Following drug discontinuation and repeated transfusions, the patient's hematologic indices returned to baseline.
Literature sources: References were obtained using MEDLINE searches, the bibliographies of articles identified during the searches, review articles, and standard textbooks.
Data synthesis: Of the two different mechanisms of TMP/SMX-induced hemolytic anemia, the reaction is most likely to occur via dose-related oxidative disruption of the erythrocyte membrane in subpopulations deficient in glucose-6-phosphate dehydrogenase (G6PD) activity. In the US, G6PD deficiency most frequently is encountered among blacks. The potential for hemolysis may be further increased in G6PD-deficient AIDS patients, who also appear to lack adequate intracellular glutathione, which is essential for protecting the erythrocyte membrane from oxidative damage. Although an assay for G6PD activity was not conducted, the case circumstances were consistent with TMP/SMX-induced hemolysis in a G6PD-deficient patient.
Conclusions: Black patients with AIDS who are receiving relatively high (greater than or equal to 50 mg/kg/d) dosages of TMP/SMX should be monitored closely for signs and symptoms of hemolytic anemia.