Monitoring of multiple solid-state transformations at tablet surfaces using multi-series near-infrared hyperspectral imaging and multivariate curve resolution.

The assessment of the solid-state stability of active pharmaceutical ingredient (API) and/or excipients in solid dosage forms during manufacturing and storage is mandatory for safeguarding quality of the final products. In this work, the solid-state transformations in tablets prepared as blends of piroxicam monohydrate, polyvinylpyrrolidone and the lactose forms monohydrate or anhydrate were studied when the tablets were exposed to the 23-120 °C range. Multi-series near-infrared hyperspectral images were obtained from the surface of each sample for unveiling the local evolution of the solid-state transformations. The preprocessed spectra from the images (dataset) were arranged in augmented matrices, according to the composition of the tablets, and the profile of the overlapped compounds (relative concentration) along the solid-state transformations in the pixels was resolved by using multivariate curve resolution--alternating least squares (MCR-ALS). Therefore, the dehydration of piroxicam and lactose monohydrates could be mapped separately in the samples (explained variances by the models >96%) even when both compounds were being transformed simultaneously (80-120 °C). The images reproduced the same trends obtained from thermogravimetric analysis of the tablets, with the advantage that the pixel-to-pixel heterogeneity of each compound at the surface of the tablets was highlighted.

Physical stability and moisture sorption of aqueous chitosan-amylose starch films plasticized with polyols.

The short-term stability and the water sorption of films prepared from binary mixtures of chitosan and native amylose maize starch (Hylon VII) were evaluated using free films. The aqueous polymer solutions of the free films contained 2% (w/w) film formers, glycerol, or erythritol as a plasticizer, as well as acetic acid (1%) and purified water. Characterization of the present fresh and conditioned film formers and free films was done using X-ray diffraction analysis, determination of moisture sorption isotherms, and near infrared spectroscopy. The results indicated that clear changes in the crystallinity of the films are evident within a 3-month period of storage, and the changes in the solid state are dependent on the plasticizer and storage conditions. When stored at ambient conditions for 3 months, the aqueous chitosan-amylose starch films plasticized with erythritol exhibited a partly crystalline structure. This was as a result of sugar recrystallisation due to the high hydrogen bonding. The respective films plasticized with glycerol and stored at 25 degrees C/60% relative humidity (RH) or at 40 degrees C/75% RH remained flexible and amorphous for at least 3 months. The water sorption of the free films greatly increased as a function of storage time at 75 and 95% RH. The second derivative spectra of starting material and free films were capable of distinguishing the internal water from the free water after storage at different relative humidities. Free water resulted in a separate band at a lower wavelength (1903 nm) in comparison to the structured absorbed water band at 1920 nm, in the case of films the free water resulted in a band around 1900 nm.