A Systematic Experimental and Computational Analysis of Commercially Available Aliphatic Polyesters

Microwave Synthesis of Nanostructured Functionalized Polylactic Acid (nfPLA) for Incorporation Into a Drug Crystals to Enhance Their Dissolution

Active pharmaceutical ingredients that have low aqueous solubility pose a challenge in the field of drug delivery. In this paper we report for the first time the synthesis of nano-structured, hydrophilized polylactic acid (nfPLA) and its application in the delivery of low solubility drugs. Microwave induced acid oxidation was used to generate nfPLA where the oxygen concentration increased from 27.0 percent to 41.0 percent. Also, the original non dispersible PLA was converted to a relatively dispersible form with an average particle size of 131.4 nm and a zeta potential of -23.3 mV. Small quantities of the nfPLA were incorporated into the crystals (0.5 to 2.0 % by weight) of a highly hydrophobic, low solubility antifungal drug Griseofulvin (GF) to form a composite (GF-nfPLA). An antisolvent approach was used for the synthesis of the drug composite. SEM and Raman imaging showed non-uniform distribution of the nfPLA on the crystal surface. The solubility of GF increased from 8.89 µg/mL to as high as 49.67 µg/mL for the GF-nfPLA. At the same time zeta potential changed from -15.4 mV to -39.0 mV, therefore the latter was a relatively stable colloid. Octanol-water partitioning also showed a similar effect as logP reduced from 2.16 for pure GF to 0.55 for GF-nfPLA. In vitro dissolution testing showed six times higher aqueous solubility of GF-nfPLA compared to pure GF. The time for 50 (T50) and 80 % (T80) dissolution reduced significantly for the nfPLA composites; T50 reduced from 40.0 to 14.0 min and T80 reduced form unachievable to 47.0 min. Overall, the PLA which is an FDA approved, bioabsorbable polymer can be used to enhance the dissolution of hydrophobic pharmaceuticals and this can lead to higher efficacy and lower the required dosage for drugs.

Biomimetic clotrimazole-loaded PLGA films with enhanced adhesiveness for controlled drug release

Biomimetic adhesive surfaces have a number of potential applications in the pharmaceutical and biomedical fields. Fabrication techniques must be adapted to biocompatible and biodegradable materials required for controlled drug release applications. In this study biomimetic adhesive poly(lactic-co-glycolic acid) (PLGA) films loaded with different concentrations of clotrimazole (CTZ) were prepared without combining other adhesive excipients as a controlled release system for potential local oral drug delivery. The films were fully characterized from morphological point of view, and CTZ-loaded biomimetic films exhibited adequate surface pH values, high drug encapsulation efficiency, and loading content. The adhesion strength of the obtained films was significantly higher compared to a flat film reference under different contact conditions. Thermal analysis indicated a decrease of drug crystallinity upon incorporation into PLGA films. The in vitro release of CTZ from PLGA biomimetic films was tested in simulated saliva, and it exhibited an initial burst release, accompanied by a sustained release phase over 10 days. Finally, the mucoadhesive properties of the obtained films was studied using agar/mucin plate as a representative mucosal substrate, and the results demonstrated superior mucoadhesion potential of CTZ-loaded biomimetic film in comparison to its flat counterpart. Having demonstrated the ability to load CTZ into PLGA biomimetic films with enhanced adhesion capacity, the potential use in local oral drug delivery applications warrants further in vitro and in vivo investigations.

Influence of PLGA molecular weight distribution on leuprolide release from microspheres

Poly (lactide-co-glycolide) (PLGA) is a biodegradable copolymer used in many long-acting drug products. The objective of the present study was to investigate the influence of polymer molecular weight distribution differences of PLGA on the in vitro release profile of leuprolide acetate microspheres. Eight microsphere formulations were prepared using the same manufacturing process but with different PLGA polymers. The physicochemical properties (drug loading, particle size and morphology) as well as the in vitro release profiles of the prepared microspheres were evaluated using a sample-and-separate method. The amount of burst release increased with increasing amount of low molecular weight fractions of PLGA, indicating that the drug release profiles appeared to be affected not only by the average molecular weight but also the molecular weight distribution of PLGA. In conclusion, quality control of the molecular weight distribution of PLGA as well as the weight average molecular weight is highly desirable in order to control the burst release.