Non-destructive Raman Method Development for Quantifying Active Pharmaceutical Ingredient in an Oral Suspension Through Plastic Dosing Syringes.

For liquid drug products, e.g., solutions or suspensions for oral or parenteral dosing, stability needs to be demonstrated in primary packaging during storage and in dosing devices during in-use periods per quality guidelines from the International Conference on Harmonisation (ICH) and the European Agency for the Evaluation of Medicinal Products (EMEA). One aspect of stability testing for liquid drug products is in-use stability, which typically includes transferring the liquid samples into another container for further sample preparation with extraction diluent and necessary agitation. Samples are then analyzed with traditional chromatography methods, which are laborious, prone to human errors, and time-consuming, especially when this process needs to be repeated multiple times during storage and in-use periods. Being able to analyze the liquid samples non-destructively would significantly improve testing efficiency. We investigated different Raman techniques, including transmission Raman (TRS) and back scatter Raman with a non-contact optic (NCO) probe, as alternative non-destructive tools to the UHPLC method for API quantitation in in-use liquid samples pulled into plastic dosing syringes. The linearity of the chemometric methods for these two techniques was demonstrated by cross-validation sample sets at three levels over an API concentration range of 60 to 80 mg/mL. The accuracy of the chemometric models was demonstrated by the accurate prediction of the API concentrations in independent samples from four different pilot plant batches manufactured at different sites. Both techniques were successful in measuring a signal through a plastic oral dosing syringe, and predicting the suspension API concentration to within 4% of the UHPLC-measured value. For future work, there are opportunities to improve the methodology by exploring additional probes or to expand the range of applications by using different sample presentations (such as prefilled syringes) or formulation matrices for solutions and suspensions.