FK778 is a synthetic malononitrilamide (MNA) that has been demonstrated to have both both immunosuppressive and anti-proliferative activities. The MNAs inhibit both T-cell and B-cell function by blocking de novo pyrimidine synthesis, through blockade of the pivotal mitochondrial enzyme dihyroorotic acid dehydrogenase (DHODH), and the inhibition of tyrosine kinase activity. FK778 has been demonstrated to prevent acute allograft rejection in multiple experimental transplant models in rodents, dogs and primates and to be effective in the rat model of chronic renal allograft rejection. In addition, FK778 has been shown to prevent vascular remodeling after mechanical intimal injury via a mechanism which may be related to tyrosine kinase inhibitory activity in vascular smooth muscle cells. Another intriguing activity of the MNA family is the ability to block replication of members of the Herpes virus family with in vitro evidence that of efficacy against cytomegalovirus (CMV) and polyoma virus, important pathogens in the transplant recipient. FK778 is currently being explored in a number of trials in solid organ transplant recipients.
Animals ; Clinical Trials, Phase I ; Humans ; Immunosuppressive Agents/*therapeutic use ; Isoxazoles/*therapeutic use ; Nitriles/chemical synthesis ; *Organ Transplantation ; Randomized Controlled Trials ; Treatment Outcome

Modified Release (MR) tacrolimus is an extended release formulation of tacrolimus (Prograf (R) ) administered once daily in the morning. In healthy volunteers, the MR tacrolimus formulation given qd AM and Prograf administered twice daily (bid) have a similar exposure (AUC) and trough levels (Cmin), with a reduced peak level (Cmax). Subsequently, pharmacokinetic studies were performed in stable kidney and liver transplant recipients converted from Prograf bid to MR tacrolimus qd AM. The steady-state tacrolimus exposure and target trough level range of MR tacrolimus were equivalent to Prograf after a mg-for-mg daily dose conversion in these two groups of patients, and there is a high correlation of exposure to trough levels for both Prograf and MR tacrolimus, as well as significantly less intra-subject variability in exposure after conversion to MR tacrolimus. These results indicate that stable kidney and liver transplant recipients can be safely converted from standard Prograf twice daily dosing to the same mg- for-mg daily dose of MR tacrolimus once daily in the morning. Hopefully a once daily dosing regimen of tacrolimus can improve patient compliance while maintaining effective immunosuppression.
Delayed-Action Preparations ; Humans ; Immunosuppressive Agents/*administration & dosage/therapeutic use ; *Kidney Transplantation ; *Liver Transplantation ; Tacrolimus/*administration & dosage/therapeutic use