Sensitive UHPLC-MS/MS method for the determination of tacrolimus in minipig whole blood

Background: Tacrolimus, a potent immunosuppressant drug widely used systemically to reduce the risk of organ rejection in transplants, has been repositioned for topical treatment of atopic dermatitis. Results & methodology: This work describes the optimization of a new method for the determination of tacrolimus in whole blood after topical administration. Sample treatment consisted of an automated procedure based on protein precipitation followed by solid-phase extraction. The present method showed good performance with quantitation limits of 10 pg ml^-1 and intra- and interday precision and accuracy lower than 15 and 10%, respectively. Conclusion: A new highly sensitive UHPLC-MS/MS method has been developed enabling a better characterization of the minipig blood plasma pharmacokinetic behavior of tacrolimus after topical administration.