Comparison of the degradation and release behaviors of poly(lactide‐co‐glycolide)–methoxypoly(ethylene glycol) microspheres prepared with single‐ and double‐emulsion evaporation methods

Abstract

The purpose of this study was to compare the degradation and release behaviors of poly(lactide‐co‐glycolide) (PLGA)–methoxypoly(ethylene glycol) microspheres fabricated by the single‐emulsion evaporation method (DEEM) and double‐emulsion evaporation methods (DEEM). Vancomycin and mizolastine were used as the hydrophilic and hydrophobic model drugs, and they were encapsulated into microspheres through DEEM and SEEM, respectively. The two types of microspheres were similar in size distribution, but the mizolastine‐loaded microspheres showed a much higher encapsulation efficiency than those loaded with vancomycin. Scanning electron microscopy, size, and molecular weight (Mw) analyses during the degradation revealed that the microspheres fabricated by DEEM underwent a bulk degradation process and showed a faster MW reduction rate during the early degradation period than the microspheres fabricated by SEEM, which exhibited a surface‐to‐bulk degradation process according to the Mw and morphological changes. The mass loss rates of the two types of microspheres were similar, but the mean size decrease rates showed a little difference. The mizolastine‐loaded microspheres exhibited an approximately linear release profile after the initial burst release, whereas the vancomycin‐loaded microspheres showed a more severe burst release, a faster release rate, and thus, a shorter time to full release. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41943.

Drug-loaded poly(d,l-lactide-co-glycolide) microspheres as treatment for allergic contact dermatitis in mice model

“…A slight burst release around 15.4% of total drug is observed during the first day, and after that the microspheres exhibit an approximate linear release rate in the later 6 days, which should be controlled by PLGA degradation behavior. 27 Most of the drugs (95.31%) are released within a week, as shown in Figure 2. According to the release results, we design the total therapy time of 8 days for the allergic contact dermatitis in the mice model.…”

Controlled Delivery of Pan-PAD-Inhibitor Cl-Amidine Using Poly(3-Hydroxybutyrate) Microspheres

“…Thus, this mechanism of surface erosion is a desirable element of the polymeric drug delivery system since it contributes to achieving a stable, zero-order pattern of sustained drug release which maintains the release of a constant amount of the encapsulated drug from within the microspheres, per unit time, regardless of the initial drug concentration [ 106 , 107 ]. According to the current study results, there was a burst release of ~50% of Cl-amidine in the first 24 h attributed to the surface associated drug [ 95 ]. This was then followed by a slower phase of zero order release from that point up to 16 days, by which point approximately 93% of the drug had been released ( Figure 6 ).…”

“…Besides, the EE of doxorubicin within poly(3-hydroxybutyrate-co-3-hydroxyvalerate) nanoparticles was 22.9% ± 1.7 [ 93 ], whilst encapsulating vancomycin within the same polymeric microspheres achieved an EE of 27.3% [ 94 ]. A slightly higher value of vancomycin EE was reported in case of using poly(lactide-co-glycolide)– methoxypoly(ethylene glycol) microspheres which is equal to 55.2% [ 95 ]. Additionally, loading of alendronate sodium into polycaprolactone based nanoparticles achieved an EE of 34% [ 96 ], whilst P(3HB) microspheres, similar to those applied in this study, with encapsulated gentamicin exhibited a similar EE of 48% [ 75 ].…”

“…Porosity was the key determinant of Cl-amidine diffusivity and release from within the P(3HB) microspheres [ 99 ]. Due to the hydrophilic nature of Cl-amidine (70 mg/mL solubility in water according to Selleckchem and Merck indices), its molecules tend to form a honeycomb porous structure across certain areas within the microsphere matrices which contain the formed water channels upon solvent evaporation during microsphere production, where Cl-amidine is efficiently distributed, encapsulated and further released through accelerating the water uptake and thus penetration into the encapsulating microspheres [ 75 , 95 ]. This honeycomb porous structure is formed while applying the double emulsion–solvent evaporation technique for the production of the P(3HB) microspheres with hydrophilic Cl-amidine as well as the hydrophilic rhodamine encapsulated control [ 39 , 100 ].…”

Development of Levodopa-loaded inhalable dry powders for treatment of Parkinson's disease via the pulmonary system

“…(Han et al 2016;Kamaly et al 2016). Water-soluble drugs such as Levodopa will thus, facilitate water penetration into particles and allow for the formation of a highly-porous polymer network upon drug leaching (Feng et al 2015). It was noted that for PLGA (50:50) particles, the drug release was observed in two phasesthe first phase showed a rapid decline in the molecular weight with little mass loss whereas it was the opposite during the second phase, thereby indicating the biodegradation to be a heterogeneous process where diffusion is the primary method of drug release, followed by erosion of the matrix (Parikh et al 2010).…”