Monitoring Cyclosporine Absorption: A Step Beyond Therapeutic Drug Monitoring

In their recent large, retrospective, cross-sectional study with 7702 renal-transplant patients, Einollahi et al. showed that cyclosporine (CsA) absorption (CA) steadily increases over 3 years post transplant (1). They also indicated that despite the day-to-day and inter-individual variability in CA, the CsA levels are routinely monitored by measuring the predose blood trough level (C0) or the 2-h post-dose level (C2). Their approach was to use the C2/ C0 ratio as a measure of CA because it takes into account both the elimination and absorption phases, which are required to identify high and low CsA absorbers (1).