Effect of Drug Carrier Melting Points on Drug Release of Dexamethasone-Loaded Microspheres

Abstract

Here, we examined the effect of melting point of drug carriers on drug release of dexamethasone (Dex)-loaded microspheres. We prepared poly(L-lactide-ran-e-caprolactone) (PLC) copolymers with varying compositions of poly(ecaprolactone) (PCL) and poly(L-lactide) (PLLA). As the PLLA content increased, the melting points of PLC copolymers decreased from 61 to 43°C. PLC copolymers in vials solubilized at 40-50°C according to the incorporation of PLLA into the PCL segment. Dexamethasone (Dex)-loaded PLC (MC x L y) microspheres were prepared by the oil-in-water (O/W) solvent evaporation/extraction method. The preparation yields were above 70%, and the mean particle size ranged from 30 to 90 lm. The MC x L y microspheres also showed controllable melting points in the range of 40-60°C. Dex-loaded MC x L y microspheres showed similar in vitro and in vivo sustained release patterns after the initial burst of Dex. The in vitro and in vivo order of the Dex release was MC 80 L 20 [ MC 90 L 10 [ MC 95 L 5 , which agreed well with the melting point order of the drug carrier. Using in vivo fluorescence imaging of fluorescein (FI)-loaded microspheres implanted in animals, we confirmed the sustained release of FI over an extended period. In vivo inflammation associated with the PLC microsphere implants was less pronounced than that associated with Poly(lactide-co-glycolide) (PLGA). In conclusion, we successfully demonstrated that it is possible to control Dex release using Dex-loaded MC x L y microspheres with different melting points.

Targeted drug-loaded PLGA-PCL microspheres for specific and localized treatment of triple negative breast cancer

“…4b show that the glass transition, Tg and melting (endothermic peak) temperatures, Tm of PLGA-PCL increased slightly in the presence loaded drug and the change in heat capacity, ∆Cp decreased in the presence of encapsulated drug loading as shown in Table 2 . The increase in Tg in the drug-loaded systems, may have been responsible in the decrease of polymer mobility via thermal induced structural relaxation of polymer in a way that reduces the rate of diffusion and promotes sustain release of the drug from the encapsulated drug polymer system [ 85 ]. This suggests that the drugs are reasonably miscible with the blend of polymers for the control and localize release [ 86 ].…”

Dexamethasone: Insights into Pharmacological Aspects, Therapeutic Mechanisms, and Delivery Systems

“…Polylactic acid (PLA) is categorized as an aliphatic polyester because of the ester bonds that connect the monomer units . PLA-based NPs have a key role in the biomedical field with a wide range of applications. − PLA has been recognized as a multipurpose material with high-biodegradability and -biocompatibility properties and approved for use by the FDA . PLA has been used in suture threads, bone fixing screws, medical devices, and drug delivery vehicles .…”

An Injectable Click-Crosslinked Hydrogel that Prolongs Dexamethasone Release from Dexamethasone-Loaded Microspheres

“…To date, a number of techniques have been developed to prepare drug-loaded microspheres, including double emulsion, organic phase separation, and spray drying methods [7,8]. In previous studies, our group has manufactured drug-loaded microspheres using a monoaxial nozzle of an ultrasonic atomizer [9,10,11]. The advantages of this ultrasonic atomizer include a simple preparation process, high yield, and abundantly encapsulated drug.…”