Inclusion Criteria:
* Age 18-75
* Are judged healthy enough to participate as determined by and decided from a pre-enrollment screening session that includes medical history and laboratory tests such as blood and urine tests, and electrocardiography (EKG).
* Agree to refrain from taking any prescription medications, over-the-counter medications, and herbal, dietary, and alternative supplements that may interact with the metabolism of the study drugs at least 2 weeks prior to the start of the study and until study completion.
* Are willing to commit the time requested for this study
* Are willing to refrain from smoking or use of tobacco or marijuana for at least two weeks prior to and until the completion of the study (the entire study lasts for approximately 26 days).
Additional Criteria for the Healthy volunteer study:
• Have a GFR above 60 ml/min/1.73m2 with proteinuria less than 0.3 grams by urine protein to creatinine ratio or 24 hour urine collection
Additional Criteria for the CKD study:
* Have either:
* A GFR less than or equal to 60 ml/min/1.73m2 or
* The presence of greater than 0.3 grams of proteinuria by urine protein to creatinine ratio or 24 hour urine collection, but less than 3.5 gm of nephrotic range proteinuria as hypoalbuminemia may impact protein binding.
Exclusion Criteria:
* Unable to provide informed consent
* Have history of intolerance, allergic reactions (e.g. rash) or other forms of hypersensitivities to any of the study medications (tacrolimus or cannabidiol);
* Are currently taking sedative agents, including agents for insomnia
* Are underweight (body mass index (BMI) less than 18.5) or overweight \[body mass index (BMI) greater than 35\]
* Have a positive pregnancy serum or urine test obtained just prior to each study, or are breast feeding
* Are night shift workers
* Are on dialysis
* Have compromised liver function as defined by pre-screening bilirubin, AST and ALT testing including any elevation of bilirubin or AST/ALT more than 2x the upper limit of normal.
* Are not willing to refrain from smoking or use of marijuana for at least two weeks prior to and until the completion of the study
* Have a Hgb \< 10.0 g/dL
* Have gastrointestinal (digestive) disorders such as persistent diarrhea or malabsorption that would interfere with the absorption of orally administered drugs
* Have a history of or current seizure disorder
* Are currently on immunosuppression or are immunosuppressed.
* Are recipients of a current allograft (heart, kidney, pancreas, liver, intestine, lung, stem cell transplant).
* Have baseline EKG readings that are abnormal that could place the patient at the high risk.
* Have alcohol (more than 4 alcoholic drinks per day on a regular basis) or drug abuse, including opioids, or have used tobacco products or marijuana within the past three months, and are unwilling or unable to stop taking these medications two weeks prior to and during the entire study period
* Have participated in a research study involving intensive blood sampling or have donated blood within the past two months
* Had an unplanned hospitalization in the last 6 months or two or more unplanned hospitalizations in the last 2 years.
* Are taking prescription medications, that may interfere with the metabolism of the study drugs (e.g., inhibitors or inducers of CYP3A4/5 or CYP2C19 or those that will displace protein binding of tacrolimus/cannabidiol). Interactions will be screened according to the Flockhart table.
* Are taking over-the-counter medications, herbal or dietary supplements, and alternative medicines that may interfere with the metabolism of the study drugs (e.g., inhibitors or inducers of CYP3A4/5 or CYP2C19 or those that will displace protein binding of tacrolimus/cannabidiol) that the subject is unwilling or unable to stop over the course of the study. Interactions will be screened according to the Flockhart table.
* Are students under supervision of any of the study investigators.
* Cannot commit the time requested for this study.
* Have a known CYP3A4 \*22/\*22 genotype
