Tacrolimus 19-epimer

Tacrolimus 19-epimer is a derivative of tacrolimus, a powerful immunosuppressive drug used to prevent organ rejection after a transplant. Tacrolimus 19-epimer, also known as 19-nor-tacrolimus or 19-O-demethyl tacrolimus, is a metabolite of tacrolimus that has been found to have similar immunosuppressive properties. It is believed to bind to the same intracellular receptor as tacrolimus, called FKBP-12, and inhibit the activation of T-cells, which play a key role in the immune response. The usage of tacrolimus 19-epimer is limited due to its low concentration in the blood compared to tacrolimus. However, it has been studied as a potential alternative to tacrolimus in some cases where tacrolimus is contraindicated or poorly tolerated. One study found that tacrolimus 19-epimer was effective in preventing acute rejection in a small group of kidney transplant recipients. From a chemical perspective, tacrolimus 19-epimer is similar to tacrolimus but lacks the O-demethyl group at position 19. This structural difference affects its pharmacokinetics and its ability to bind to FKBP-12. Tacrolimus 19-epimer has a molecular weight of 794.05 g/mol and a chemical formula of C44H69NO11. It is metabolized in the liver and excreted in the feces and urine. Like tacrolimus, tacrolimus 19-epimer has a narrow therapeutic range, and careful monitoring of blood levels is necessary to avoid toxicity.