Systemic Absorption of Low‐Dose Oral Vancomycin

Abstract

BackgroundThe absorption of oral vancomycin is usually minimal. However, in the presence of renal impairment and inflammatory disorders of the intestinal mucosa, it may be absorbed to a significant extent. Case reports and literature reviews suggest that this is generally not an issue unless doses of vancomycin above 2 g/day are used for prolonged periods.AimTo describe a case of persistently high serum vancomycin levels associated with low oral doses of vancomycin.Clinical featuresA 59 year‐old obese woman with neutropenic sepsis and renal impairment was treated with intravenous meropenem and vancomycin. Oral vancomycin 125 mg 6‐hourly was commenced for antibiotic‐associated diarrhoea due to Clostridium difficile. Intravenous vancomycin was ceased after 4 doses because serum levels were > 20 mg/L. Serum vancomycin levels remained > 16 mg/L for over a week, even after reducing the oral dose from 500 mg to 300 mg/day.OutcomeVancomycin levels steadily decreased after ceasing oral vancomycin in the presence of worsening renal function.ConclusionSignificant absorption of low doses of oral vancomycin may occur resulting in therapeutic levels. The extent of absorption is unpredictable, therefore monitoring of serum vancomycin levels is recommended in at risk patients.