C2 monitoring of cyclosporine in de novo liver transplant recipients: the clinician's perspective.

Adjusting cyclosporine (CsA) dose based on blood concentration at 2 hours after dose (C(2)) has been shown in prospective clinical trials to reduce the risk of rejection compared with conventional trough monitoring. In addition, it provides equivalent efficacy to tacrolimus in liver transplant patients, with a favorable safety profile. Target C(2) should be defined on an individual basis depending on adjunctive therapy and the level of exposure required. It appears less critical to achieve target C(2) in the first few days after liver transplantation than was previously believed. Achieving target C(2) exposure in the initial period after transplant requires that changes in the proportion of cyclosporine absorbed from the gut be taken into account to avoid risk of overexposure. In addition, if a starting dose of 10-15 mg/day is used, it is advisable to delay increasing the dose until a trend in C(2) level indicates this to be necessary. Immediate dose reduction is required if C(2) exceeds target range. In patients with low C(2) values, cyclosporine concentration at a later time point should be measured to establish whether the patient is a poor absorber or a delayed absorber of C(2), and dose adjustments should be undertaken accordingly. In conclusion, this more flexible approach to C(2) monitoring allows the dose of cyclosporine to be individualized effectively for each patient, which results in significant efficacy benefits while minimizing the risk of toxicity.