Absorption of oral aminoglycosides following bone marrow transplantation.

Four patients with severe gastrointestinal reactions receiving oral "nonabsorbable" antibiotics for gut sterilization following bone marrow transplantation absorbed clinically significant amounts of aminoglycoside (gentamicin and/or tobramycin). Serum concentrations of 2.2, 2.6, 5.8, and 12.0 micrograms/ml were measured. Two of these patients had acute graft versus host reactions and two had severe mucositis following cytoreduction with intensive chemotherapy and irradiation. Nephrotoxicity occurred in the latter patients. One patient was studied in detail. Her hospital course and investigative results are presented. Four additional patients with mild gastrointestinal reactions following cytoreduction did not absorb gentamicin when their toxicity was maximal. Serum aminoglycoside determinations are necessary in patients receiving oral aminoglycosides for gut sterilization following bone marrow transplantation if moderate to severe gastrointestinal reactions occur.