Infrared Spectroscopy/stoichiometric Characterization Study Of Nifedipine Solid Dispersion

1,4-dihydropyridine calcium channel blockers have been widely used in the treatment of cardiovascular disorders,but these drugs will recrystallization in their solid dispersions after long time storage.The objective of the present research was to study the feasibility of using Fourier transform infrared spectrometry(FTIR)based chemometric models in quantifying crystalline and amorphous nifedipine(NF)from its amorphous solid dispersions(SD).Three SDs respectively containing PVP,Soluplus and PVP/VA were prepared and the nifedipine was found to be amorphous form which was confirmed by X-ray powder diffraction(XRD)and differential scanning calorimetry(DSC).Then the quantitative analysis models were constructed by the following steps:(1)Crystalline physical mixture was mixed with SD in various proportions to prepare sample matrices containing different amount of amorphous/crystalline NF.(2)FTIR of the samples were measured.(3)Principal component analysis was used to determine the most appropriate FTIR band.(4)Using spectral pretreatment methods to treat the spectral data.(5)Building quantitative analysis models.(6)The chosen model was used to analyze the solid dispersion samples.In this research the 1900-700 cm-1 band of FTIR data was mathematically pretreated using multiple Savitzky-Golay and multiplicative scatter correction(MSC)before partial-least-square regression(PLS)and artificial neural network(ANN).The ANN models were more accurate than PLS for FTIR data.Long-term stability of the systems against crystallization evaluated by ANN model suggested that stability is related to the strength of intermolecular interactions present.The results showed that the FTIR combine with chemometrics can predict the amount of nifedipine in the solid dispersions with high accuracy(RMSEP<1.6%)and sensitivity(Limit of quantitation<5%)which is better than XRD.Polymers could be sorted by their effects of inhibiting NF crystallization in the descending order:PVP>PVP/VA>Soluplus.