for people ages 18 years and up (full criteria)
study started
estimated completion



Transplant patients must take lifelong immunosuppression in order to prevent rejection of their organ. Tacrolimus is the most widely used immnosuppressive agent. Part of the routine education given to patients regarding tacrolimus is that they must avoid many drugs and substances that can interact with tacrolimus so that they don't experience side effects or lack of effect. Patients are told they must avoid readily available substances such as grapefruit juice and St. John's wort. A new once daily formulation of tacrolimus, Envarsus XR, may bypass the place in the gut in which many of these drug interactions occur. We will give kidney transplant patients Envarsus with and without grapefruit juice and measure the effect on blood levels throughout the day. Results from this study will also give us information about the likelihood of other drugs interacting with Envarsus XR.

Official Title

Assessment of the Intestinal CYP3A Contribution to Drug Interactions With Envarsus XR Using Grapefruit Juice


Kidney Transplant; Complications Drug Interaction Food Tacrolimus Grapefruit Juice CYP3A4 Midazolam Kidney Transplant


You can join if…

Open to people ages 18 years and up

  • Primary Kidney Transplant Age > 18 years At least 3 months post-transplantation Taking a stable dose of tacrolimus extended release with a target trough of 8-10 ng/mL BMI between 18-32

You CAN'T join if...

  • Multi-organ transplant Concomitant use of mTOR inhibitor Concomitant use of belatacept Concomitant use of medication affecting CYP3A or P-gp History of rejection Hypersensitivity to midazolam Hypersensitivity to Envarsus Active diarrhea or constipation BMI < 18 or > 32


not yet accepting patients
Start Date
Completion Date
Shirley M. Tsunoda
Phase 4
Study Type
Last Updated