Milk-alkali syndrome and tacrolimus metabolism

Chronic immunosuppressive therapy is critical to all transplant patients to help prevent rejection, chronic injury and loss of allograft. Tacrolimus is used as immunosuppression in more than ninety percent of kidney transplant recipients, and requires drug level monitoring. It is known that many prescribed medications can alter tacrolimus metabolism and lead to unpredictable levels that may expose patients to the above-mentioned complications. However, the use of over-the-counter medications is often overlooked. Here, we present a case report in which over-the-counter calcium carbonate significantly affected the patient's tacrolimus metabolism leading to unpredictable levels.