Characterization of Mannitol Polymorphic Forms in Lyophilized Protein Formulations Using a Multivariate Curve Resolution (MCR)-Based Raman Spectroscopic Method

Purpose To develop a novel multivariate curve resolution (MCR)-based Raman spectroscopic method to characterize and quantify five known mannitol solid-state forms in lyophilized protein formulations. Materials and Methods The multivariate quantitation method was developed based on second derivative Raman spectra of three anhydrous crystalline forms (α-, β-, and δ-mannitol), a hemihydrate and an amorphous mannitol form. The method showed a 5% quantitation limit of mannitol forms in lyophilized model protein formulations. Binary mixtures of β- and δ-mannitol combined with evaluation of the prediction residue were used for the method validation. X-ray powder diffractometry data was used to confirm the existence of mannitol forms in the sample. Results The various polymorphic forms of mannitol were characterized and quantified based on the Raman spectra of the existing pure forms, and the results are consistent with the X-ray powder diffraction data. This Raman method has been demonstrated for the application of monitoring and controlling of mannitol polymorphic forms in the lyophilized drug products during formulation and process development. It has implications in monitoring and improving the quality of the drug product. Conclusions An MCR-Raman method has been developed for the quantitative determination of five different mannitol polymorphic forms in the presence of sucrose and protein.