Tacrolimus Trough Level Variation and Its Correlation to Clinical Outcomes and Consequences in Solid Organ Transplantation

Sarah Albilal,1,* Mohammad S Shawaqfeh,2– 4,* Salwa Albusaysi,5 Lolwa Fetyani,2,3 Fai Alnashmi,2,3 Shaden D Alshehri,2,3 Nataleen A Albekairy,6 Amal Akhulaif,2 Lamees Alzahrani,2 Mariah Alwuhayde,2 Aiman A Obaidat,2,3,7 Abdulkareem M Al Bekairy1– 3,* 1Department of Pharmaceutical Care, King Abdulaziz Medical City-Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia; 2College of Pharmacy, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia; 3King Abdullah International Medical Research Center (KAIMRC), Riyadh, Saudi Arabia; 4Department of Pharmacy Practice, College of Pharmacy, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia; 5Department of Pharmaceutics, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Saudi Arabia; 6College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia; 7Department of Pharmaceutical Sciences, College of Pharmacy, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabi*These authors contributed equally to this workCorrespondence: Abdulkareem M Al Bekairy, College of Pharmacy, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia, Tel +966505550055, Email bekairya@ngha.med.sa; bekairy@gmail.com Mohammad S Shawaqfeh, College of Pharmacy, Department of Pharmacy Practice, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia, Tel +966502590643, Email shawaqfehm@ksau-hs.edu.sa; Shawaqfehms@gmail.comPurpose: Tacrolimus is a calcineurin inhibitor that suppresses immunity by inhibiting T-lymphocyte activation. It has a high intra- and inter-patient variability in its pharmacokinetics. Therefore, therapeutic drug monitoring is required to individualize the dose. High tacrolimus trough level variability is associated with a higher risk of adverse effects. In practice, the initial dosing and sampling time of tacrolimus levels is not standardized