Abstract
In this paper, the synergistic effect of ultrasound and polyethylene glycol (PEG) on the controlled release of a water soluble drug from polylactide (PLA) matrices was studied. When ultrasound was used following the hot melt extrusion (HME) of the PLA/model drug release system, the release of the model drug (Methylene Blue (MB)) from the PLA when immersed in phosphate buffered saline (PBS) was affected by the variation of the parameters of ultrasound. It was found that no more than 2% PLA dissolved during the in-vitro release study, and the release of the MB from the PLA was diffusion controlled and fit well with the Higuchi diffusion model. Polyethylene glycol (PEG), which has high hydrophilicity and rapid dissolution speed, was blended with the PLA during the melt extrusion to enhance the release of the MB. The analysis of the structure and properties of the in-vitro release tablets of PLA/PEG/MB indicated that the ultrasound could improve the dispersion of MB in the PLA/PEG blends and it could also change the structure and properties of the PLA/PEG blends. Due to the dissolution of the PEG in PBS, the release of the MB from the PLA/PEG drug carrier was a combination of diffusion and erosion controlled release. Thus a new mechanism combining of diffusion and erosion models and modified kinetics model was proposed to explain the release behavior.
Highlights
The development of controlled release products is one of the important applications of biodegradable and bioresorbable polymers [1,2,3,4,5]
1.5 g dried PLA/Methylene blue (MB) or PLA/polyethylene glycol (PEG)/MB granules were filled into the cell shown in Figure 1 and kept 35 intensities was induced at 170 ◦ CPLA-35%PEG6000 for 5min, the ultrasound irradiation with different to the melts for 0 or 3PLA-50%PEG6000 min, held at 170 C for an additional or min to make sure that the total treating time at 170 ◦ C was 10min
In the first 20 days, the release rates of MB from the tablets treated by ultrasound were faster than that from the tablets without ultrasound treatment
Summary
The development of controlled release products is one of the important applications of biodegradable and bioresorbable polymers [1,2,3,4,5]. As reported in the literature, most of the PLA based drug delivery systems have been prepared by traditional methods involving solvent processes. They have showed various problems, such as environmental pollution and residual organic solvent [27]. To our knowledge, there have been only a few reports on the release behavior of PLA based drug delivery system prepared by melt processing. Our goal for the research described here was to develop a PLA based long term drug delivery system and control the release behavior by melt blending and subsequent ultrasound treatment. The effect of subsequent ultrasound melt treatment and blending hydrophilic polyethylene glycol (PEG) with the PLA in the extrusion process on the release behavior of model drug was studied
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