Background: Mycophenolate mofetil (MMF) is the prodrug
of mycophenolic acid (MPA). Proton pump inhibitors
impair exposure to MPA due to incomplete conversion
from MMF. Lower exposure to MPA could result in an
increased risk of acute rejection. We investigated whether MMF-treated renal transplant patients who concomitantly used pantoprazole as ulcer prophylaxis had a higher risk of acute rejection within the first three months after transplantation than those who used ranitidine. Methods: We performed a retrospective study in adult patients who underwent kidney transplantation between January 2007 and December 2011. Their immunosuppressive therapy consisted of steroids, tacrolimus and MMF and they used either pantoprazole or ranitidine as ulcer prophylaxis. Results: 202 patients were included: 125 using pantoprazole and 77 using ranitidine. There was no difference in the number of patients with biopsy-proven acute rejection (BPAR): 13 (10.4%) in the pantoprazole group versus 7 (9.1%) in the ranitidine group (NS). Also after correction for inequalities between the two groups, there was no significant relationship between the risk of BPAR and the type of anti-ulcer agent. Conclusion: There was no evidence for an increased incidence of BPAR in renal transplant patients who use pantoprazole in combination with MMF.