OBJECTIVE To determine plasma aluminum concentrations and 24-hr urine aluminum excretion rate in long-term mechanically ventilated patients treated with 6 g of sucralfate daily for stress ulcer prophylaxis. METHODS Prospective study in long-term mechanically ventilated critically ill patients. METHODS A surgical intensive care unit at a university hospital. METHODS Eleven long-term mechanically ventilated patients (multiple trauma [n = 8], abdominal surgery [n = 3]) were included in the study. The mean age of the patients was 57.2 +/- 10.8 yrs and the mean duration of treatment was 11.3 +/- 4.2 days. METHODS 1 g of sucralfate suspension intragastrically six times daily. RESULTS Baseline plasma aluminum concentrations were determined at the beginning of the study. Patients received 1 g of sucralfate suspension given intragastrically six times daily via a nasogastric tube. Daily plasma aluminum concentration was measured 3 hrs after the morning dose of sucralfate. The urine aluminum excretion rate was determined from the 24-hr urine samples. Determinations of plasma and urine aluminum concentrations were carried out by flameless atomic absorption spectrophotometry. Renal function was compromised in eight patients (maximum plasma creatinine concentration 2.7 mg/dL [238.7 mumol/L]; normal value < 1.4 mg/dL [< 123.8 mumol/L]). Mean daily plasma aluminum concentration varied between 7.5 +/- 1.6 micrograms/L (278 +/- 59.3 nmol/L) and 21.1 +/- 7.1 micrograms/L (782 +/- 263.1 nmol/L) (normal value < 10 micrograms/L [< 371 nmol/L]). The 24-hr urine aluminum excretion rate varied between 25.7 +/- 18.1 and 53.4 +/- 87.2 micrograms/L (952.4 +/- 671 and 1979 +/- 3232 nmol/L) (normal value < 12.2 micrograms/L [< 452 nmol/L]). Aluminum accumulation did not occur in any of the patients. CONCLUSIONS The administration of 6 g of sucralfate daily in long-term mechanically ventilated surgical patients did not result in an increase in the plasma aluminum concentration. Sucralfate can be administered safely for a period of at least 2 wks, even in critically ill patients with impaired renal function.