Z.; Statistical optimization of reverse phase high performance liquid chromatography for the analysis of caffeine paracetamol and its degradation product p-aminophenol; Acta Chimica Slovenica

Abstract Paracetamol, analgoantipyretic and anti-inflammatory drug, is available in numerous pharmaceutical formulations in common combination with caffeine and some other drug substances. p-aminophenol is paracatamol's process-related impurity that also may be present in formulations containing paracetamol. This paper presents a RP-HPLC method for simultaneous determination of caffeine, paracetamol and p-aminophenol, using chromatographic system Hewlett Packard 1100 series. In defining optimal RP-HPLC chromatographic conditions for the separation of these three compounds, experimental design was applied. Completely separation was achieved using Zorbax Extend C18 column (150 mm × 4.6 mm, 5 µm), with mobile phase consisting of methanol-phosphate buffer pH 6 (20:80 v/v), flow rate of 1 ml/min, and column temperature of 30 °C. UV detection was performed at 230 nm

Potential application of low molecular weight excipients for amorphization and dissolution enhancement of carvedilol

In this study, four low molecular weight (LMW) excipients, tryptophan (TRY), phenylalanine (PHE), lysine (LYS) and saccharin (SAC) were evaluated as co-formers to generate co-amorphous systems (CAMS) by ball milling with carvedilol (CRV). Mixtures of CRV and LMW excipient in 1:0.5, 1:1 and 1:2 drug:excipient molar ratios were ball milled and analysed by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), Fourier transform (FT-IR) infrared spectroscopy and dissolution testing. CAMS were formed by milling of a mixture of CRV with TRY in 1:2 M ratio and SAC in 1:1 M ratio, while amorphization of only CRV was achieved in other mixtures with SAC. In other samples containing TRY and PHE, milling resulted in partial amorphization, while LYS was the least suitable excipient for the amorphization of CRV. Unexpectedly, the highest supersaturation of CRV was achieved from samples containing CRV and LYS in 1:1 and 1:2 M ratios, despite the absence of a significant reduction in CRV crystallinity upon milling of these samples. Increase of hydrophobic surface area caused by milling of samples with TRY and PHE and agglomeration during dissolution testing of samples containing SAC are likely causes of poor dissolution performance of mixtures containing fully or partially amorphous CRV