Influence of Hydroxypropyl Methylcellulose on Metronidazole Crystallinity in Spray-Congealed Polyethylene Glycol Microparticles and Its Impact with Various Additives on Metronidazole Release.
The purpose of this study was to investigate the effect of a hydrophilic polymer, hydroxypropyl methylcellulose (HPMC), on the crystallinity and drug release of metronidazole (MNZ) in spray-congealed polyethylene glycol (PEG) microparticles and to further modify the drug release using other additives in the formulation. HPMC has been used in many pharmaceutical formulations and processes but to date, it has not been employed as an additive in spray congealing. Crystallinity of a drug is especially important to the development of pharmaceutical products as active pharmaceutical ingredients (APIs) are mostly crystalline in nature. A combination of X-ray diffractometry, differential scanning calorimetry, Raman spectroscopy and Fourier transform-infrared spectroscopy (FT-IR) spectroscopy was employed to investigate the degree of crystallinity and possible solid-state structure of MNZ in the microparticles. The microparticles with HPMC were generally spherical. Spray congealing decreased MNZ crystallinity, and the presence of HPMC reduced the drug crystallinity further. The reduction in MNZ crystallinity was dependent on the concentration of HPMC. Smaller HPMC particles also resulted in a greater percentage reduction in MNZ crystallinity. Appreciable modification to MNZ release could be obtained with HPMC. However, this was largely attributed to the role of HPMC in forming a diffusion barrier. Further modification of drug release from spray-congealed PEG-HPMC microparticles was achieved with the addition of 5% w/w dicalcium phosphate but not with magnesium stearate, methyl cellulose, polyvinylpyrrolidone, silicon dioxide and sodium oleate/citric acid. Dicalcium phosphate facilitated formation of the diffusion barrier.
GEA-NUS Pharmaceutical Processing Research Laboratory, Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore, 117543, Singapore.
Ching Mien
CM
Oh
GEA-NUS Pharmaceutical Processing Research Laboratory, Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore, 117543, Singapore.
Paul Wan Sia
PW
Heng
GEA-NUS Pharmaceutical Processing Research Laboratory, Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore, 117543, Singapore. phaclw@nus.edu.sg.
Lai Wah
LW
Chan
D002152:Calorimetry, Differential Scanning / Q000379:methods; D002626:Chemistry, Pharmaceutical / Q000379:methods; D003460:Crystallization / Q000379:methods; D065546:Drug Liberation; D065347:Hypromellose Derivatives / Q000737:chemistry*; D008795:Metronidazole / Q000737:chemistry*; D008863:Microspheres; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D011205:Povidone / Q000737:chemistry; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013059:Spectrum Analysis, Raman / Q000379:methods; D014961:X-Ray Diffraction / Q000379:methods
D008795:Metronidazole; D065347:Hypromellose Derivatives; D011092:Polyethylene Glycols; D011205:Povidone
crystallinity; drug release; hydroxypropyl methylcellulose; metronidazole; spray congealing