Once Daily Dosing to Improve Medication Adherence and Patient Satisfaction in Kidney Transplant Recipients

The current pilot study will first demonstrate the safety and feasibility of converting maintenance transplant recipients to a once daily regimen, while measure of patient satisfaction and adherence are secondary outcomes. The purpose of this study is to determine the safety and feasibility of converting maintenance kidney transplant recipients (i.e. those more than one year post transplantation) to a once daily drug regimen (including immunosuppressant and non-immunosuppressant drugs). We believe that conversion to a once daily (O.D.) medication regimen for both immunosuppressive and non-immunosuppressive medications will be associated with increased patient adherence and satisfaction.

Immunosuppressant non-adherence is considered the leading potentially avoidable cause of allograft failure, with non-adherent patients having a seven fold higher odds of graft failure than adherent patients. Although medication non-adherence is multi-factorial, simplification of medication requirements has been associated with improved adherence in the non-transplant setting.

There are few prospective studies examining strategies to improve immunosuppressant adherence. The proposed study has significant potential to improve medication adherence and satisfaction in kidney transplant recipients which may ultimately lead to an improvement in long-term outcomes.

The major barrier to establishing a once daily medication regimen in maintenance kidney transplant recipients (i.e. patients ≥ 12 months post transplantation) was related to the requirement to prescribe calcineurin inhibitors twice daily. The development of Advagraf (tacrolimus extended release capsules), which is approved for prevention of rejection in kidney transplant recipients, now provides an opportunity to convert patients to a once daily immunosuppressant medication regimen.

The other maintenance immunosuppressant medications used in kidney transplantation are Mycophenolic acid (MPA), azathioprine and prednisone.

Mycophenolic acid (MPA) was first made available for use in kidney transplantation in 1995 in the form of the prodrug mycophenolate mofetil (MMF); this was later followed by the introduction of mycophenolate sodium (Myfortic).

The recommended dose of MMF and Myfortic are 2g/day and 1440 mg/day respectively in de novo transplant recipients. In clinical practice, maintenance patients (i.e. those who are more than 1 year post transplantation) are often not maintained on the recommended initial (see below). In studies involving patients prescribed the recommended initial daily dose, MPA exposure is highly variable: The 12 hour area under the curve (AUC) ranges anywhere between 15 and 115 mg*h/L. In the first post transplant year, a 12 hour AUC of 30 -60 mg*h/l is recommended based on studies showing an increased incidence of rejection when the AUC < 30 mg*h/l, and no additional efficacy benefit with AUC > 60 mg*h/l in cyclosporine treated patients.

A relationship between MPA exposure and acute rejection beyond 3 months has not been demonstrated. There is a paucity of studies examining the concentration-effect relationship beyond the first post transplant year and thus there are no established recommendations for MPA exposure after the first post-transplant year. In clinical practice a significant proportion of long-term (≥ 1 year post transplant) MPA treated patients will be prescribed less than the recommended dose of MPA due to a variety of reasons including patient intolerance (usually gastrointestinal or hematological). Most reductions in MPA dose are undertaken in the first few months after transplantation when renal allograft dysfunction or hypoalbuminemia may have increased free MPA exposure and possibly increased drug related side effects. Importantly recent controlled studies in both de novo and maintenance transplant patients have demonstrated the safety of once daily MPA dosing using less than the initial recommended daily dose.

Prednisone may or may not be prescribed in maintenance transplant recipients. Maintenance prednisone dose varies between 5 -10 mg once daily or every other day.

Azathioprine is an established once daily medication.

A significant criticism of one daily immunosuppressant regimens has been that patients will still be required to take other medications multiple times per day. Uniquely the proposed study will convert all medications (immunosuppressant and non-immunosuppressants) to a once daily regimen.

In summary, advances in immunosuppressant drugs now make it possible to consider a once daily immunosuppressant regimen in maintenance kidney transplant recipients.

Eligible patients will be screened and consented at the hospital by the study team. The conversion to a once daily dosing regimen will be accomplished in three phases: 1) conversion to Advagraf; 2) conversion of non-immunosuppressant drugs and; 3) conversion of patients taking twice daily MPA to once daily MPA.