Critical evaluation of methods for end-point determination in pharmaceutical blending processes

This paper compares existing approaches to the monitoring of pharmaceutical blending processes and the detection of their end-point by use of near infrared spectroscopy (NIRS). To this end, we examined homogenization in a pharmaceutical mixture containing a relatively low concentration (<4%) of an API that exhibits low absorption in the NIR region and is difficult to blend with excipients. The end-point of the process (viz. where a uniform distribution of the API in the mixture was reached) was determined by using various qualitative and quantitative spectral treatments for comparison. The results revealed the capabilities of different spectral treatments for establishing blend homogeneity, which can be especially useful with a view to optimizing their industrial use. API distribution uniformity in the final blend was confirmed by near infrared chemical imaging (NIR-CI) analysis.