title: Investigation of the solid state properties of amoxicillin trihydrate and the effect of powder pH.
abstract: The purpose of this research was to investigate some physicochemical and solid-state properties of amoxicillin trihydrate (AMT) with different powder pH within the pharmacopoeia-specified range. AMT batches prepared using Dane salt method with the pH values from 4.39 to 4.97 were subjected to further characterization studies. Optical and scanning electron microscopy showed that different batches of AMT powders were similar in crystal habit, but the length of the crystals increased as the pH increased. Further solid-state investigations using powder x-ray diffraction (PXRD) demonstrated the same PXRD pattern, but the intensity of the peaks raised by the powder pH, indicated increased crystallinity. Differential scanning calorimetry (DSC) studies further confirmed that as the powder pH increased, the crystallinity and, hence, thermal stability of AMT powders increased. Searching for the possible cause of the variations in the solid state properties, HPLC analysis showed that despite possessing the requirements of the United States Pharmacopoeia (USP) for purity/impurity profile, there was a direct relationship between the increase of the powder pH and the purity of AMT, and also decrease in the impurity I (alpha-Hydroxyphenylglycine) concentration in AMT powder. Recrystallization studies confirmed that the powder pH could be controlled by adjusting the pH of the crystallization.
authors.affiliation: Medicinal Plants and Drugs Research Institute (MPDRI), Shahid Beheshti University, Evin, PO Box 19835/389, Tehran, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Ghassempour
authors.forename: Hasan
authors.initials: H
authors.lastname: Rafati
authors.forename: Laleh
authors.initials: L
authors.lastname: Adlnasab
authors.forename: Yosef
authors.initials: Y
authors.lastname: Bashour
authors.forename: Homeira
authors.initials: H
authors.lastname: Ebrahimzadeh
authors.forename: Mohammad
authors.initials: M
authors.lastname: Erfan
mesh_terms: D000658:Amoxicillin / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D003460:Crystallization; D018360:Crystallography, X-Ray; D004355:Drug Stability; D005998:Glycine / Q000031:analogs & derivatives / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D033362:Powder Diffraction; D011208:Powders; D013678:Technology, Pharmaceutical / Q000379:methods; D013696:Temperature
chemical_list: D000900:Anti-Bacterial Agents; D011208:Powders; D000658:Amoxicillin; D005998:Glycine