The development of polycarbophil as a bioadhesive material in pharmacy

Polycarbophil(PCP),a kind of pharmaceutical polymers with superior bioadhesive properties has been widely used in the field of controlled drug delivery systems.It could be used as a highly efficient thickener,bioadhesive agent,suspending aid and emulsion stabilizer when dispersed in water or other polar solvents.These exceptional utilities of the polymers result from their hydrophilic nature.Hydrogen bonding plays an important role in most adhesion behaviours and becomes the main adhesion force.This paper reviews the applications of PCP in pharmacy over the past decades,and clarifies its unique advantages in the bioadhesive formulations.After an introduction discussing its structural characteristics and action mechanism,the focus turned to the description of its available applications in detail with particular emphasis on the ocular,nasal,vagina and oral drug delivery systems.The other less developed formulations are also described,including the buccal and the transdermal delivery systems.

A simple method to improve the dissolution of repaglinide and exploration of its mechanism

In the present study,a simple and rapid method was developed to improve the in vitro dissolution of repaglinide,an oral antidiabetic drug,which was based on addition of meglumine in 50%(v/v)ethanol to dissolve repaglinide,and the drug dissolved in meglumine/50%ethanol was used directly with a binder to prepare tablets.The mechanism of solubilization of repaglinide by meglumine was studied by using infrared spectrum(IR),ultraviolet(UV)measurement through dual wavelength,differential scanning calorimetry(DSC)and X-ray powder diffraction methods.Dissolution tests of repaglinide tablets were performed in the media with different pH values and the repaglinide concentrations were analyzed by High Performance Liquid Chromatography(HPLC)method.The solubility data showed that with the meglumine concentration increasing,the solubility of repaglinide was increased.Meanwhile,tablets with the molar ratio of repaglinide and meglumine 1:2(n/n)resulted in a significant increase in dissolution compared to the repaglinide tablets without using meglumine,and nearly equal to the commercial preparations of Novo-Norm^(®),which concluded that meglumine had a great role in promoting the dissolution of repaglinide.The results of IR and UV dual wavelength methods suggested the formation of repaglinideemeglumine(REPeMEG)molecular complex.DSC results showed that the melting peak of repaglinide disappeared in the REPeMEG coprecipitate,which indicated that repaglinide was stable when existing at amorphous or molecular state.The experiment of X-ray powder diffraction showed that with the solubilization of meglumine,the crystal diffraction peak of repaglinide disappeared,which further inferred that repaglinide was formed complexes with meglumine.It was demonstrated that the method of improving repaglinide with meglumine was reliable and could be suitable for repaglinide tablets production in industry.This study also provides a feasible way to enhance the dissolution of drugs with low solubility,which will be leading to improved bioavailability of these drugs.