Process analytical technology: nondestructive evaluation of cyclosporine A and phospholipid solid dispersions by near infrared spectroscopy and imaging

The objective of this study was to evaluate near infrared (NIR) spectroscopy and imaging as approaches to assess phospholipid compartment within its solid dispersion with cyclosporine A (CyA). By varying dimyristoyl phosphatidylcholine (DMPC) to CyA weight ratio, five batches were prepared by the kneading technique and characterized by DSC and FTIR. A drug/DMPC ratio of 50:1 provided an enhanced dissolution of CyA. FTIR spectra and DSC thermograms revealed a significant interaction between the drug and DMPC which suggested incorporation of CyA within the formed DMPC liposomes. The developed NIR calibration model was able to assess DMPC concentrations within the kneaded products. The calibration and prediction linear plots showed slopes of 0.9711 and 0.9915, offsets of 0.1247 and 0.1080, correlation coefficients of 0.9854 and 0.9889 and root mean square standard errors of 0.43% and 0.42%, respectively. In contrast, NIR spectral imaging was capable of clearly distinguishing the kneaded products, both qualitatively and quantitatively. NIR imaging revealed the poor powder blending efficiency of the method used to prepare physical mixture compared to the efficient distribution of the kneaded products. In conclusion, NIR spectral imaging system provides a rapid approach for acquiring high-resolution spatial and spectral information on solid dispersions.