ABSTRACT
In this study, we reported the application of Povacoat®, a hydrophilic polyvinylalcohol copolymer, as a dispersion stabilizer of nanoparticles of poorly water-soluble compounds. In addition, the influence of aggregation of the nanoparticles on their solubility and oral absorption was studied. Griseofulvin (GF) was used as a model compound with poor water solubility and was milled to nanoparticles by wet bead milling. The dispersion stability of GF milled with Povacoat® or the generally used polymers (polyvinylalcohol, hydroxypropylcellulose SSL, and polyvinylpyrrolidone K30) was compared. Milled GF suspended in Povacoat® aqueous solution with D-mannitol, added to improve the disintegration rate of freeze-dried GF, exhibited high dispersion stability without aggregation (D90 = ca. 0.220 µm), whereas milled GF suspended in aqueous solutions of the other polymers aggregated (D90 > 5 µm). Milled GF with Povacoat® showed improved aqueous solubility and bioavailability compared with the other polymers. The aggregation of nanoparticles had significant impact on the solubility and bioavailability of GF. Povacoat® also prevented the aggregation of the various milled poorly water-soluble compounds (hydrochlorothiazide and tolbutamide, etc.) more effectively than the other polymers. These results showed that Povacoat® could have wide applicability to the development of nanoformulations of poorly water-soluble compounds.
Subject(s)
Excipients/chemistry , Griseofulvin/chemistry , Nanoparticles , Polymethyl Methacrylate/chemistry , Polyvinyl Alcohol/chemistry , Administration, Oral , Animals , Biological Availability , Cellulose/analogs & derivatives , Cellulose/chemistry , Chemistry, Pharmaceutical , Crystallization , Drug Stability , Freeze Drying , Griseofulvin/administration & dosage , Griseofulvin/pharmacokinetics , Hydrophobic and Hydrophilic Interactions , Kinetics , Male , Mannitol/chemistry , Nanotechnology , Polyvinyl Alcohol/analogs & derivatives , Povidone/chemistry , Rats, Sprague-Dawley , Solubility , Technology, Pharmaceutical/methodsABSTRACT
There are various opinions regarding the different functions of original and generic drugs. We used the paddle method to perform dissolution tests on pravastatin sodium tablets (10 mg) to investigate the causes for these differences. We used water and buffer solutions adjusted to pH 1.2 (JP1) and pH 6.8 (JP2), which are described in the Japanese Pharmacopoeia. The pravastatin concentration was measured by UV spectroscopy and HPLC. There were significant differences in the percentages dissolved of original and generic drugs after 5 and 10 min. On the other hand, the dissolution behaviors using water and JP2 measured by HPLC were similar to the results obtained by UV spectroscopy. However, the percentage dissolved of pravastatin using JP1 decreased with time because pravastatin degraded in JP1. There were also significant differences in the pravastatin concentrations of the original and generic drugs at 5, 15, 30, and 45 min. Based on the above results, since the original drug has a slower dissolution rate than the generic drugs, it is necessary to be cautious about the degradation of pravastatin in the stomach and the bioavailability of pravastatin due to the different dissolution rates and the different residual amount of pravastatin in the stomach.
