Pharmacokinetics of Sublingual Versus Oral Tacrolimus in Patients Awaiting Kidney Transplantation

Tacrolimus (Prograf) belongs to a class of medications known as the calcineurin inhibitors. It is a maintenance drug that is used to prevent rejection in kidney, liver, and heart transplant recipients. Calcineurin inhibitors display high pharmacokinetic (the body's effects on a drug) variability and necessitate use of blood tests to ensure that adequate drug levels are present to maintain effectiveness and safety. Early after transplant or at times when tacrolimus cannot be taken by mouth, alternative routes of administration are sought. Although an intravenous (through the vein) product is available, it can be toxic to the kidneys and has been associated with allergic reactions. Drug delivery via the oral mucosa is an alternative method of systemic drug administration which offers an alternative when oral administration is impractical (gastrointestinal dysmotility, reduced drug absorption, intestinal failure, difficulty in swallowing, or in those with nausea or vomiting). Administration of tacrolimus by the sublingual route may allow for direct entry into the systemic circulation and bypasses problems associated with drug absorption and breakdown that take place in the small intestine.