Towards a better understanding of the release mechanisms of caffeine from PLGA microparticles

Abstract

Poly(lactic‐co‐glycolic acid) (PLGA)‐based microparticles can be successfully used to control the release rate of a drug and optimize the therapeutic efficacy of a medical treatment. However, the underlying drug release mechanisms can be complex and are often not fully understood. This renders system optimization cumbersome. In this study, differently sized caffeine‐loaded PLGA microparticles were prepared and the swelling and drug release behaviors of single microparticles were monitored upon exposure to phosphate buffer pH 7.4. Ensembles of microparticles were characterized by X‐ray diffraction, differential scanning calorimetry, scanning electron microscopy, gel permeation chromatography, and optical microscopy. The observed triphasic drug release patterns could be explained as follows. The initial burst release can be attributed to the dissolution of tiny drug crystals with direct surface access. The subsequent second drug release phase (with an about constant release rate) could be attributed to the release of drug crystals in regions, which undergo local swelling. The third release phase (again rapid, leading to complete drug exhaust) could be explained by substantial polymer swelling throughout the systems. Once a critical polymer molecular weight is reached, the PLGA chains are sufficiently hydrophilic, insufficiently entangled and the osmotic pressure created by water soluble degradation products attracts high amounts of water into the system. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48710.

Kinetics of Drug Release via Nicardipine Hydrochloride‐loaded Carboxymethyl Cellulose/Poly(D,L‐lactic‐co‐glycolic acid) Nanocarriers Using a Contemporary Emulsion Process

“…The NCH‐CMC/PLGA nanocarriers could have a transition in size through liquid absorption as a stimulus. The swelling degree of the nanocarriers was determined by incubation at 37 °C and pH 7.4 in phosphate‐buffered saline (PBS) to simulate the body fluids in normal tissues [15,18] . The nanocarriers were synthesized according to the optimal parameters (see Section 1.5).…”

“…The swelling degree of the nanocarriers was determined by incubation at 37°C and pH 7.4 in phosphate-buffered saline (PBS) to simulate the body fluids in normal tissues. [15,18] The nanocarriers were synthesized according to the optimal parameters (see Section 1.5). The particle size of the nanocarriers was measured as~170 nm, and incubated samples were investigated using the DLS technique.…”

“…PLGA is widely used in the pharmaceutical field, including in drug and gene delivery applications. [13][14][15][16] PLGA is an aliphatic and hydrophobic polyester that is potentially biocompatible and biodegradable, which can minimize drug residues in the body. [15,17] Previously, PLGA carriers for NCH encapsulation have been via a double emulsion process.…”

“…[13][14][15][16] PLGA is an aliphatic and hydrophobic polyester that is potentially biocompatible and biodegradable, which can minimize drug residues in the body. [15,17] Previously, PLGA carriers for NCH encapsulation have been via a double emulsion process. [13,18] The results showed that PLGA microparticles appeared to prevent NCH deterioration by hydrolysis.…”

“…This study focuses on poly(D,L‐lactic‐co‐glycolic acid) (PLGA) nanocarriers. PLGA is widely used in the pharmaceutical field, including in drug and gene delivery applications [13–16] . PLGA is an aliphatic and hydrophobic polyester that is potentially biocompatible and biodegradable, which can minimize drug residues in the body [15,17] .…”