Elaboration of Charged Poly(Lactic-co-Glycolic Acid) Microparticles for Effective Release of Tranexamic Acid

Abstract

In this study, tranexamic acid (TA) was used as a model compound to study the charge effect on the physicochemical properties of poly(lactic-co-glycolic acid) (PLGA) microparticles (MPs). Charged PLGA MPs were elaborated by the incorporation of a quaternary ammonium, cetyltrimethylammonium bromide (CTAB), during the double emulsion solvent evaporation process. Three TA-CTAB-carrying modes of PLGA MPs were designed in the CTAB-free (TA-MP), adsorption (TA-CTABAD), or encapsulation (TA-CTABEN) form. The obtained MPs were characterized by morphology and TA-MP affinity. The experiment revealed that the three prepared MPs were spherical and smooth, with pores on their surfaces. TA-CTABAD had a relatively narrow size distribution, compared with that of TA-MP and TA-CTABEN. The particle sizes of TA-MP, TA-CTABEN, TA-CTABAD were measured as 59 ± 17, 54 ± 20, and 19 ± 8 μm, respectively. The zeta potential of the three MPs was found to be in the order: TA-CTABAD > TA-CTABEN > TA-MP. Differential scanning calorimetry (DSC) indicated that the manufacturing process had no influence on the glass transition temperature of the MPs, which was close to 48 °C. Thermogravimetric analysis illustrated that the presence of CTAB slightly changed the thermal stability of PLGA MPs. In vitro release showed that TA-CTABAD exhibited faster TA release than TA-MP and TA-CTABEN in a basic environment (pH of 13), probably because of electrostatic attraction. At pH = 1, the release of TA from TA-CTABEN was faster than those from TA-MP and TA-CTABAD, probably because of electrostatic repulsion. However, the effect of electrostatic interaction was not significant at pH = 7.4.

Experiment and Correlation of the Osmotic Coefficient for the Aqueous Solution of Weak Acids Using the NRTL-NRF Model

“…Phenolic acids, i.e., ascorbic, gallic, and salicylic acids are important intermediate organic compounds with various properties, including anti-fungi, anti-cancer, and anti-bacterial activities. − Ascorbic acid (Vitamin C) is an anti-oxidative agent which plays an important role in the tissue repair and the enzymatic production of certain neurotransmitters . Meanwhile, gallic and salicylic acids are also applied in natural dyes and drugs. ,, From among carboxylic acids, lactic acid, glycolic acid, and isovaleric acid have vast usage in pH regulators, natural polymers, and solvents, drugs, as well as antimicrobial compounds. − …”