Bioavailability of Sandimmun® versus Sandimmun Neoral®: a meta-analysis of published studies

For the past 25 years, cyclosporine A (CyA) has played a pivotal role in transplant immunosuppressant therapy. From the availability of the 2 primary marketed formulations (Sandimmun® and Sandimmun Neoral®, Novartis), confusion has existed with regard to whether these two formulations are bioequivalent. Due to the underlying clinical relevance of this information, we therefore conducted a meta-analysis of all available comparative pharmacokinetic studies to assess whether the two different CyA formulations, Sandimmun® and Sandimmun Neoral®, can be considered bioequivalent. All clinical studies that compared the bioavailability of the 2 formulations in organ transplant recipients were considered for analysis. We searched computerised databases (Embase/Excerpta Medica and Medline/PubMed) from their inception to May 2010. Only studies with AUC values determined at 12 hours were considered for analysis. Relative bioavailability was calculated with 90 percent confidence intervals (CI) for Sandimmun® (test substance) versus Sandimmun Neoral® (reference substance) according to Schuirmann?s Two One-Sided Tests Procedure and the Classical Shortest CI. Homogeneity of data was tested using the Χ(2) test. Fifteen studies were considered for meta-analysis and none of these studies reported AUC values in the 80-125 percent range required for the bioequivalence of two formulations. The overall bioavailability for Sandimmun® versus the microemulsion formulation Sandimmun Neoral® was 76 percent, with upper CI limits lower than 80 percent in some cases. Mean AUC values for Sandimmun® were significantly lower than those for Sandimmun Neoral® (p<0.01). This study demonstrates that the 2 main cyclosporine formulations, Sandimmun® and Sandimmun Neoral®, cannot be considered bioequivalent.