Determination of Residual Moisture in Lyophilized Protein Pharmaceuticals Using a Rapid and Non-Invasive Method: Near Infrared Spectroscopy

Abstract

This study examined the application of near-infrared (NIR) spectroscopy to analyze residual moisture in lyophilized protein pharmaceuticals sealed in glass vials. We demonstrated that NIR was able to determine residual moisture in five marketed and clinical products with the same precision as Karl Fischer titration. We further investigated how changes in product configuration and protein formulation affected NIR measurement accuracy using a lyophilized monoclonal antibody rhuMAb E25 containing 1% to 5% residual moisture. The results indicated that the lyophilized cake porosity and dimensions had no effect on NIR measurement when the cake height and diameter exceeded the NIR penetration depth. In addition, changing the buffer and surfactant concentrations in the formulation did not affect moisture determination by NIR. However, doubling or halving the concentration of a disaccharide, which was used as a lyoprotectant, caused significant deviation between the NIR and Karl Fischer data because the NIR absorbance of the disaccharide overlapped with the moisture signal. Furthermore, complete removal of the disaccharide resulted in alteration of the protein NIR spectra, suggesting that NIR may be used to evaluate solid-state protein structure. The disaccharide concentration must be kept constant in this formulation to obtain accurate moisture results by NIR.