Applicability of a natural swelling matrix as the propellant of osmotic pump tablets / 药学学报

The purpose of this study is to investigate the applicability of a natural swelling matrix derived from boat-fruited sterculia seed (SMS) as the propellant of osmotic pump tablets. The sugar components, static swelling, water uptake and viscosity of SMS were determined and compared with that of polythylene oxide (WSR-N10 and WSR-303). Both ribavirin and glipizide were used as water-soluble and water-insoluble model drugs. Then, the monolayer osmotic pump tablets of ribavirin and the bilayer osmotic pump tablets of glipizide were prepared using SMS as the osmotically active substance and propellant. SMS was mainly composed of rhamnose, arabinose, xylose and galactose and exhibited relatively high swelling ability. The area of the disintegrated matrix tablet was 20.1 times as that at initial after swelling for 600 s. SMS swelled rapidly and was fully swelled (0.5%) in aqueous solution with relative low viscosity (3.66 +/- 0.03) mPa x s at 25 degrees C. The monolayer osmotic pump tablets of ribavirin and the bilayer osmotic pump tablets of glipizide using SMS as propellant exhibited typical drug release features of osmotic pumps. In conclusion, the swelling matrix derived from boat-fruited sterculia seed, with low viscosity and high swelling, is a potential propellant in the application of osmotic pump tablets.

Real-time UV imaging of chloramphenicol intrinsic dissolution characteristics from ophthalmic in situ gel / 药学学报

In this paper, chloramphenicol was selected as a model drug to prepare in situ gels. The intrinsic dissolution rate of chloramphenicol from in situ gel was evaluated using the surface dissolution imaging system. The results indicated that intrinsic dissolution rate of chloramphenicol thermosensitive in situ gel decreased significantly when the poloxamer concentration increased. The addition of the thickener reduced the intrinsic dissolution rate of chloramphenicol thermosensitive gel, wherein carbomer had the most impact. Different dilution ratios of simulated tear fluid greatly affected gel temperature, and had little influence on the intrinsic dissolution rate of chloramphenicol from the thermosensitive in situ gel. The pH of simulated tear fluid had little influence on the intrinsic dissolution rate of chloramphenicol thermosensitive in situ gel. For the pH sensitive in situ gel, the dissolution rates of chloramphenicol in weak acidic and neutral simulated tear fluids were slower than that in weak alkaline simulated tear fluid. In conclusion, the intrinsic dissolution of chloramphenicol from in situ gel was dependent on formulation and physiological factors. With advantages of small volume sample required and rapid detection, the UV imaging method can be an efficient tool for the evaluation of drug release characteristics of ophthalmic in situ gel.

Redefinition of the genus Allonychiurus Yoshii, 1995 (Collembola, Onychiuridae) with description of a new species from China.

In this paper, we describe a new species of the genus Allonychiurus Yoshii, 1995, characterized by the presence of an apical swelling on the fourth antennal segment as well as a combination of chaetotaxic and pseudocellar characters. The genus Allonychiurus is redefined. Four of its species are considered as incertae sedis: Allonychiurus michelbacheri (Bagnall, 1948), Allonychiurus spinosus (Bagnall, 1949), Allonychiurus caprariae (Dallai, 1969) and Allonychiurus sensitivus (Handschin, 1928). The three species Allonychiurus borensis (Beruete, Arbea & Jordana, 1994), Allonychiurus sensilatus (Thibaud & Massoud, 1979) and Allonychiurus vandeli (Cassagnau, 1960) are removed from Allonychiurus and placed in Micronychiurus Bagnall, 1949, Thalassaphorura Bagnall, 1949 and Spinonychiurus Weiner, 1996 respectively. The synonymy of Thibaudichiurus Weiner, 1996 with Allonychiurus is rejected and Allonychiurus foliatus (Rusek, 1967) and Allonychiurus mariangeae (Thibaud & Lee, 1994) are re-allocated to Thibaudichiurus. List and identification key to the world species of the genus are given.