- Pharmacokinetics: Irrespective of whether a patient starts on Envarsus XR® after randomization or is switched to Envarsus XR® after 4 months of immediate release tacrolimus, the dose of Envarsus XR® will be determined by using a dose conversion ratio targeting 0.7 (but may range from 0.66-0.8 because of dosage strengths of Envarsus XR® dosing formulations) relative to the immediate release formulation that he/she was receiving as maintenance.