Development and validation of HPLC method for the determination of Cyclosporin A and its impurities in Neoral® capsules and its generic versions

Cyclosporin A (CyA) is a cornerstone immunosuppressant for the prophylaxis against allograft rejection after organ transplantation. The most widely prescribed CyA formulation is Neoral® soft gelatine capsules (Novartis Pharmaceuticals, Basel, Switzerland). After Novartis patent expiration, several generic formulations have been developed.In this paper, a simple and reliable HPLC method was developed and validated for the evaluation of four CyA degradation products (ID-005-95, CyH, IsoCyH and IsoCyA) and two related compounds (CyB and CyG) aimed for the quality control of Neoral® capsules and its generic formulations. In a second step, the validated method was then compared to the USP assay method for capsules, where some of the mentioned impurities were not adequately resolved from the CyA peak.Isocratic elution at a flow rate of 1.0 mL min−1 was employed on a Lichrospher RP-18 (4 mm × 250 mm; 5 μm) analytical column maintained at 75 °C with a tetrahydrofuran:phosphoric acid (0.05 M) (44:56, v/v) as mobile phase. The chromatograms were recorded using a Hewlett Packard 1100 chromatographic system. The UV detection wavelength was performed at 220 nm and 10 μL of sample was injected.The developed method was validated in terms of selectivity, linearity, precision, accuracy, limit of detection and limit of quantitation. The validate method was successfully applied to commercial capsules, Neoral® and generic versions. Therefore, the proposed method is suitable for the simultaneous determination of CyA as well as its major impurities.