Mycophenolic acid in kidney transplant patients with diabetes mellitus: does the formulation matter?

Diabetes mellitus is frequent in kidney transplant recipients and is commonly associated with gastrointestinal (GI) complications. Delayed gastric emptying affects 30% to 50% of patients with type 1 or 2 diabetes and can influence oral drug absorption. Time-to-peak concentration of mycophenolic acid (MPA) from mycophenolate mofetil (MMF) is longer in diabetic kidney transplant patients than patients without diabetes. By retaining gut contents in the stomach for longer, this could increase local GI toxicity in diabetic recipients due to an extended duration of exposure to MPA in the stomach. The enteric-coated mycophenolate sodium (EC-MPS) formulation delays the release of MPA until pH is higher than 5.5, such that absorption takes place more distally compared with MMF. Patient-reported outcomes data have been used to assess the effect of conversion to EC-MPS in maintenance kidney transplant patients with diabetes who were experiencing MMF-related GI symptoms. Results indicated that conversion leads to improved GI symptom burden despite higher MPA exposure under the EC-MPS regimen. Improved GI tolerance using EC-MPS has permitted maintenance of optimal MPA exposure in nondiabetic populations. Comparative trials to evaluate the GI symptom burden and maximum achieved MPA dosing using the EC-MPS and MMF formulations in de novo and maintenance diabetic kidney transplant recipients are merited.