The pharmacokinetic profiles of Sandimmune and Neoral vary considerably among transplant recipients. Cyclosporine exposure is far more consistent with Neoral than it is with Sandimmune. Because intrapatient variability of drug exposure has been demonstrated to be a risk factor for chronic rejection, this difference becomes important. Neoral also has a linear dose response and a stronger correlation between trough level and drug exposure. Dose linearity greatly facilitates accurate dose titration. Results of controlled studies in which kidney, liver, and heart transplant recipients were converted from Sandimmune to Neoral have shown that conversion on a 1:1 mg basis results in more predictable bioavailability and often in reductions in cyclosporine dose. Carefully monitored conversion has not been associated with increased side effects, and any side effects that do emerge can usually be managed by taking Neoral with food, changing the dose from every 12 hours to every 8 hours, or through dose reduction.