Polymorphic analysis of a pharmaceutical preparation by NIR spectroscopy

A method for the characterization and determination of the crystalline form present in the amorphous miokamycin of a pharmaceutical preparation using near-infrared spectroscopy (NIRS) is proposed. The study leading to the development of the proposed method involved both qualitative (classification by residual variance analysis) and quantitative aspects (the determination of both total miokamycin and its crystalline form using multivariate calibration). Samples containing less than 5% of the total amount of miokamycin in its crystalline form can be accurately classified. Partial least-squares regression (PLSR) allows low contents of the crystalline form to be determined with absolute errors less than 1.5%, which is comparable to the limit of detection of the X-ray diffraction technique used as reference. Also, the total miokamycin content is determined by NIRS with errors less than 1%. The simplicity, expeditiousness and robustness of the proposed method make it an effective tool for determining both total and crystalline miokamycin in solid dosage forms.