Polyelectrolyte Matrices in the Modulation of Intermolecular Electrostatic Interactions for Amorphous Solid Dispersions: A Comprehensive Review

Polyelectrolyte polymers have been widely used in the pharmaceutical field as excipients to facilitate various drug delivery systems. Polyelectrolytes have been used to modulate the electrostatic environment and enhance favorable interactions between the drug and the polymer in amorphous solid dispersions (ASDs) prepared mainly by hot-melt extrusion. Polyelectrolytes have been used alone, or in combination with nonionic polymers as interpolyelectrolyte complexes, or after the addition of small molecular additives. They were found to enhance physical stability by favoring stabilizing intermolecular interactions, as well as to exert an antiplasticizing effect. Moreover, they not only enhance drug dissolution, but they have also been used for maintaining supersaturation, especially in the case of weakly basic drugs that tend to precipitate in the intestine. Additional uses include controlled and/or targeted drug release with enhanced physical stability and ease of preparation via novel continuous processes. Polyelectrolyte matrices, used along with scalable manufacturing methods in accordance with green chemistry principles, emerge as an attractive viable alternative for the preparation of ASDs with improved physical stability and biopharmaceutic performance.

COMPATIBILITY SCREENING OF VIDAGLIPTIN WITH IONIC AND NON-IONIC POLYMERIC EXCIPIENTS FOR THE DESIGN OF EXTENDED RELEASE DELIVERY SYSTEM

Studies of drug-polymer compatibility play an important role in the preformulation stage for the development of pharmaceutical dosage forms. The potential physical and chemical interactions between drugs and polymer can affect the chemical nature, stability and bioavailability of the dosage form and as a result in the therapeutic response in the clinical phase. The present study reveals the thermal and spectroscopic study of physical mixtures of Vildagliptin (VDG) and HPMC in combination with cationic polymers chitosan, anionic polymers NaCMC and nonionic polymers PEO for extended release (ER). In the first phase of the study, differential scanning calorimeter (DSC) was used as tool to detect any interaction. In the next phase, a Fourier Transform Infrared Spectroscopy (FT-IR) technique was used to confirm and to investigate the type of the possible interactions between the components. In both cases, the spectroscopic data revealed that the analysed polymeric excipients did not show any affect on the VDG. Results of the present study indicated the suitability of the HPMC K4M hydrophilic matrix polymers in combination with cationic polymers, anionic polymers and non-ionic polymers in the preparation of extended release formulation of VDG.

The impact of the of cationic polyelectrolyte polymerization degree in latexes coagulation dosage of synthetic emulsion rubbers

The literature data on the parameters of coagulation of butadiene-styrene and butadiene-?-methyl styrene latexes by cationic polyelectrolytes in comparison with low-molecular ammonium compounds and nonionic polymers are discussed. The optimal dosage of cationic polyelectrolyte during coagulation of synthetic emulsion rubber latex stabilized by a combination of synthetic fatty acid Soaps and disproportionated rosin with a mixture of sodium salts of the oligomeric condensation product ?-naphthalenesulfonic acid with formaldehyde (Leukanol) is determined, ceteris paribus, by its degree of polymerization. The decrease in the optimum dosage during the transition from high molecular weight polyelectrolytes to the oligomers caused by decrease of the cationic and anionic groups ratio required for a complete binding Leukanol in the formation of oligomer-oligomer complexes compared with the polymer-oligomer complexes. This is due, apparently, the fact that an increase in the average molecular weight of the polyelectrolyte increases the proportion of so-called tails and loops, consisting of units of the polyelectrolyte that are not associated with molecules Leukanol

Application of Interpolymer Complexes of Novel Poly(ampholyteelectrolyte) as Soil Structuring Agents and for Extraction of Radioactive Strontium

<p>Novel linear copolymer exhibiting poly(ampholyte-electrolyte) behavior was involved into complexation reaction with anionic, cationic and nonionic polymers. Interpolymer complexes were prepared by mixing of aqueous solutions of individual polymers with concentration varying from 10^-1-10^-4 mol×L^-1. The formed interpolymer complexes showed the soil structuring effect and the ability to extract the radioactive strontium from the polluted topsoil of Semipalatinsk Test Site. The mechanism of soil stabilization or aggregation was explained by the fact that the soil particles bearing negative charges interact with positively charged "loops" of interpolymer complexes resulting in the formation of so called "cobweb" (or protective crust) on the soil surface. The effective capturing of radioactive strontium by interpolymer complexes may be connected with formation of more stable ternary polymer-metal complexes. It was demonstrated that: i) interpolymer complexes are the most effective soil structuring agents than that of individual components; ii) the optimal concentration of interpolymer complexes for soil aggregation is 10^-2 mol×L^-1; iii) pouring of soil surface by interpolymer complexes is more effective than the splashing; iv) the treatment of the soil by already pre-existing interpolymer complexes is most effective than the successive treatment of the soil by individual components; v) the best soil structuring properties were shown for interpolymer complexes stabilized by H–bonds and intra salt bonds.</p>