Effects of Formulation Parameters on Encapsulation Efficiency and Release Behavior of Risperidone Poly(D,L-lactide-co-glycolide) Microsphere

Su, Zhengxing; Sun, Fengying; Shi, Yanan; Jiang, Chengwei; Meng, Qingfan; Teng, Lirong; Li, Youxin

doi:10.1248/cpb.57.1251

Cited by 59 publications

(26 citation statements)

References 15 publications

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“…Blending of polyesters using carboxylic acid end-groups has previously been reported for microsphere formulations. [9][10][11][12] Acidic groups in polymer matrices are known to catalyze the degradation of polyester polymers. The aggregate results from these microsphere formulations suggested that carboxylic acid end-groups can be used to tailor or modulate the delivery of hydrophobic drugs.…”

Section: Discussionmentioning

confidence: 99%

“…9,10 Others studies have used carboxylic acid functional groups within the PLGA to increase the rate of drug delivery. 11,12 These studies suggest that PLGA matrices can be tailored via MW, terminal functional groups or both without the inclusion of additives. Despite these observations, no systematic study has been performed to quantify the influence on controlled drug release comparing both MW and terminal functional groups, especially for thin films used in medical devices.…”

Section: Introductionmentioning

confidence: 99%

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Tuning drug release in polyester thin films: terminal end-groups determine specific rates of additive-free controlled drug release

et al. 2013

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Modulating the drug release from polyester matrices independently of material properties would be beneficial to those designing biodegradable medical implants, such as drug delivery devices, stents and screws. However, the most common approaches use additives that often drastically alter the desired material properties. Recently, we have developed tools that allow gradient film formulations and high-throughput drug quantitation for the determination of parameter-specific correlations. We propose that modulated drug release can be obtained via additive-free mechanisms in polyesters by simply controlling polymer erosion through acidic terminal functional groups. Our results showed that drug release in poly(lactic-co-glycolic acid) (PLGA) formulations could be tuned to produce large ranges in drug release with relatively small changes in terminal acidic functional groups. For example, PLGA 53/47 thin films could be tuned to have 10-60% drug release at 14 days or 10-90% drug release at 20 days, depending on the PLGA/PLGA blend formulation and concentration of acidic terminal functional groups. A linear R-square correlation of up to 0.9 was observed for the acidic groups and percent drug release. Below a threshold of 1 part per thousand acidic groups, there was no increase in drug release, which has implications for polymer processing and film integrity.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tuning drug release in polyester thin films: terminal end-groups determine specific rates of additive-free controlled drug release

et al. 2013

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“…After formation of the depot, drug molecules are blocked by double diffusion barriers whereby the drug must diffuse through microspheres to the SAIB depot first and then diffuse from the SAIB depot into the media, leading to a steady and slow drug release profile. Meanwhile, due to the application of low molecular weight PLGA and the decreased particle size (<10 μm), the ultra-small microspheres will ensure continuous and complete drug release as reported in the literature (15)(16)(17)(18)(19). As a result, the microsphere/SAIB hybrid depot can not only reduce the burst release of SAIB but also significantly prolong the drug release period of microspheres prepared with low molecular weight PLGA, rendering the hybrid depot a useful and practical long-term drug delivery system.…”

Section: Introductionmentioning

confidence: 95%

“…It is therefore essential to improve the triphasic drug release behavior of PLGA microspheres to provide continuous release without a lag-release phase to maintain the therapeutic effect of the drug in PLGA microspheres. To date, many efforts have been made to eliminate the lagphase and thus obtain continuous drug release: (1) increasing the water penetration by co-encapsulation of a pore agent in microspheres such as Mg(OH) 2 (6), stearic acid (14), and medium chain triglyceride (15), (2) improving the hydrophilic nature of PLGA by using low molecular weight PLGA (15)(16)(17), (3) and controlling the drug release by diffusion by preparing small-sized microspheres (e.g., smaller than 20 μm for small molecules) (18,19). Although the above approaches all successfully eliminate the lag-release phase by increasing the drug diffusion rate during the initial stage, problems, such as burst release and a significantly shortened drug release period caused by those approaches, have occurred.…”

Section: Introductionmentioning

confidence: 99%

A Uniform Ultra-Small Microsphere/SAIB Hybrid Depot with Low Burst Release for Long-Term Continuous Drug Release

Xia

Tang

et al. 2015

Pharm Res

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“…38) In Vitro Release Study The release study on the formulations revealed prolonged release profiles of TAC, extending to more than 20 d. As reported previously, PLGA microspheres loaded with risperidone showed a sustained release profile for The value of r4 weeks as measured from the plasma drug concentration suggesting a good potential of PLGA microspheres for sustained release delivery system. 39) As the loading amount of tacrolimus was increased, the amount of PLGA per unit of the drug loaded was also decreased. As a result, the relative abundance of PLGA in the microspheres was decreased with increase in loading, which results in increase in the porosity of the microspheres with increase in drug loading.…”

Section: )mentioning

confidence: 99%

Preparation of High-Payload, Prolonged-Release Biodegradable Poly(lactic-<i>co</i>-glycolic acid)-Based Tacrolimus Microspheres Using the Single-Jet Electrospray Method

et al. 2016

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Tacrolimus-loaded poly(lactic-co-glycolic acid) microspheres (TAC-PLGA-M) can be administered for the long-term survival of transplanted organs due to their immunosuppressive activity. The purpose of our study was to optimize the parameters of the electrospray method, and to prepare TAC-PLGA-M with a high payload and desirable release properties. TAC-PLGA-M were prepared using the electrospray method. In vitro characterization and evaluation were performed using scanning electron microscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy. Drug-loading efficiency was greater than 80% in all formulations with a maximum loading capacity of 16.81 0.37%. XRD and DSC studies suggested that the drug was incorporated in an amorphous state or was molecularly dispersed in the microspheres. The in vitro release study showed prolonged release patterns. TAC-PLGA-M with enhanced drug loading and prolonged-release patterns were successfully prepared using the electrospray method.Key words electrospray; microsphere; poly(lactic-co-glycolic acid); prolonged release; tacrolimus Tacrolimus (TAC), a potent immunosuppressant drug, is primarily used to increase the survival time of transplanted organs.1) The immunosuppressive activity of tacrolimus is mediated through the inhibition of calcineurin, which is a protein phosphatase found in the cytoplasm of T-cells, and the subsequent blockage of interleukin-2 production, leading to a decrease in T cell proliferation.2) In clinical practice, tacrolimus is administered as a twice-daily dosing regimen. Modified-release tacrolimus with once daily administration has also been used safely.3) There are no reports regarding the use of prolonged release formulations of tacrolimus in clinical practice, although some polymer-based formulations for longterm delivery of tacrolimus have been used in animal model studies. As has been previously reported, a single dose of the new type of tacrolimus with biodegradable microspheres could keep the plasma concentration steady for two weeks, suggesting that immunosuppressive activity could be achieved with the use of polymer-based formulations.4,5) Subcutaneous injection of tacrolimus pellets, which could give a plasma concentration within the desired therapeutic window, provided effective immunosuppression for more than three months in rat model studies.6) Likewise, tacrolimus-loaded biodegradable microspheres reportedly achieved sustained release over a long period, giving flat parallel concentration profiles for 10 d from the first day after a single subcutaneous administration in liver-transplanted rats. 7)Long-term controlled delivery of drugs has been accomplished by the use of biodegradable polymeric particulate systems.8) Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable polymer that undergoes hydrolysis in the body to produce two monomers: lactic acid and glycolic acid. The rate of degradation of PLGA and the release profile of drugs from PLGAbased formulations depend on the mole...

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Effects of Formulation Parameters on Encapsulation Efficiency and Release Behavior of Risperidone Poly(D,L-lactide-co-glycolide) Microsphere

Cited by 59 publications

References 15 publications

Tuning drug release in polyester thin films: terminal end-groups determine specific rates of additive-free controlled drug release

Tuning drug release in polyester thin films: terminal end-groups determine specific rates of additive-free controlled drug release

A Uniform Ultra-Small Microsphere/SAIB Hybrid Depot with Low Burst Release for Long-Term Continuous Drug Release

Preparation of High-Payload, Prolonged-Release Biodegradable Poly(lactic-<i>co</i>-glycolic acid)-Based Tacrolimus Microspheres Using the Single-Jet Electrospray Method

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