Solvent selection in the preparation of poly(dl-lactide) microspheres prepared by the solvent evaporation method

Bodmeier, Roland; McGinity, James W.

doi:10.1016/0378-5173(88)90073-7

Cited by 314 publications

(154 citation statements)

References 10 publications

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“…The 'high' solubility allowed relatively fast mass-transfer between the dispersed and the continuous phases and led to fast precipitation of the polymer. The significance of solubility of the organic solvent in water was also confirmed by the fact that the addition of water-miscible co-solvents such as acetone, methanol, ethyl acetate, or dimethyl sulfoxide (DMSO), contributed to increase of the encapsulation efficiency (Bodmeier and McGinity, 1988). Knowing that the methanol is a non-solvent for PLA and a water-miscible solvent, it can be assumed that methanol played a dual function in facilitating the polymer precipitation: First, the presence of methanol in the dispersed phase decreased the polymer solubility in the dispersed phase (Jeyanthi et al, 1997).…”

Section: Solubility Of Organic Solvent In Watermentioning

confidence: 95%

“…Most attempts to increase encapsulation efficiency are based on a common idea that fast polymer precipitation on the surface of the dispersed phase can prevent drug loss into the continuous phase (Bodmeier and McGinity, 1988). On the other hand, when solidification of the dispersed phase is delayed, encapsulation efficiency becomes low because more drugs diffuse into the continuous phase ( Fig.…”

Section: Formulation Parameters Relevant To Encapsulation Efficiencymentioning

confidence: 99%

“…On the other hand, Bodmeier et al found that methylene chloride resulted in a higher encapsulation efficiency as compared with chloroform or benzene, even though methylene chloride was a better solvent for poly (lactic acid) (PLA) than the others (Bodmeier and McGinity, 1988). In order to justify this discrepancy, the authors point out that methylene chloride is more soluble in water than chloroform or benzene.…”

Section: Solubility Of Organic Solvent In Watermentioning

confidence: 99%

“…First, when highly concentrated, the polymer precipitates faster on the surface of the dispersed phase and prevents drug diffusion across the phase boundary (Rafati et al, 1997). Second, the high concentration increases viscosity of the solution and delays the drug diffusion within the polymer droplets (Bodmeier and McGinity, 1988).…”

Section: Polymer Concentrationmentioning

confidence: 99%

“…If the solubility of the drug in the continuous phase is higher than in the dispersed phase, the drug will easily diffuse into the continuous phase during this stage. For example, the encapsulation efficiency of quinidine sulfate was 40 times higher in the alkaline continuous phase (pH 12, in which quinidine sulfate is insoluble) than in the neutral continuous phase (pH 7, in which quinidine sulfate is very soluble) (Bodmeier and McGinity, 1988). In another example, the encapsulation efficiency of rhodium(II) (Rh(II)) citrate in PLGA or poly(anhydride) was significantly enhanced after complexation with hydroxypropyl-β-cyclodextrin (HPBCD) (Sinisterra et al, 1999).…”

Section: Solubility Of Drug In Continuous Phasementioning

confidence: 99%

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Control of encapsulation efficiency and initial burst in polymeric microparticle systems

2004

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Initial burst is one of the major challenges in protein-encapsulated microparticle systems. Since protein release during the initial stage depends mostly on the diffusional escape of the protein, major approaches to prevent the initial burst have focused on efficient encapsulation of the protein within the microparticles. For this reason, control of encapsulation efficiency and the extent of initial burst are based on common formulation parameters. The present article provides a literature review of the formulation parameters that are known to influence the two properties in the emulsion-solvent evaporation/extraction method. Physical and chemical properties of encapsulating polymers, solvent systems, polymer-drug interactions, and properties of the continuous phase are some of the influential variables. Most parameters affect encapsulation efficiency and initial burst by modifying solidification rate of the dispersed phase. In order to prevent many unfavorable events such as pore formation, drug loss, and drug migration that occur while the dispersed phase is in the semi-solid state, it is important to understand and optimize these variables.

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Section: Solubility Of Organic Solvent In Watermentioning

confidence: 95%

Section: Formulation Parameters Relevant To Encapsulation Efficiencymentioning

confidence: 99%

Section: Solubility Of Organic Solvent In Watermentioning

confidence: 99%

Section: Polymer Concentrationmentioning

confidence: 99%

Section: Solubility Of Drug In Continuous Phasementioning

confidence: 99%

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Control of encapsulation efficiency and initial burst in polymeric microparticle systems

2004

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Microporous microparticles designed as stable immunoadsorbents

Ubrich

Rivat

Vigneron

et al. 1998

Biotechnol. Bioeng.

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Drug-delivery system based on core-shell-type nanoparticles composed of poly(?-benzyl-L-glutamate) and poly(ethylene oxide)

Nah

Jeong

Cho

2000

J. Appl. Polym. Sci.

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A block copolymer based on poly(␥-benzyl-L-glutamate) (PBLG) as the hydrophobic part and poly(ethylene oxide) (PEO) as the hydrophilic part was synthesized and characterized. PBLG/PEO/PBLG (GEG) block copolymer nanoparticles were prepared using the dialysis technique. Fluorescence spectroscopy measurement suggested that GEG block copolymers were associated in water to form polymeric micelles and the critical micelle concentration (CMC) value of the GEG-50 block copolymer was 0.0084 g/L. Particle-size distribution of the GEG-50 block copolymer based on the number average was 34.9 Ϯ 17.6 nm. Also, the particle size and drug-loading contents of GEG nanoparticles were significantly changed with the initial solvent used. From transmission electron microscope (TEM) observations, the GEG polymeric micelle was a nice spherical shape and the sizes ranged from approximately 20 -60 nm in diameter. Results from assessing the drug-loading contents against the initial solvent showed that the use of tetrahydrofuran (THF) or 1,4-dioxane as the initial solvent resulted in higher drug-loading contents than those of other solvents. In the drug-release studies, the higher the molecular weight of the polymer and drug-loading contents, the slower the drug release. Also, the initial solvent used was significantly affected not only in the drug-loading contents but also in the drug-release kinetics.

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Solvent selection in the preparation of poly(dl-lactide) microspheres prepared by the solvent evaporation method

Cited by 314 publications

References 10 publications

Control of encapsulation efficiency and initial burst in polymeric microparticle systems

Control of encapsulation efficiency and initial burst in polymeric microparticle systems

Microporous microparticles designed as stable immunoadsorbents

Drug-delivery system based on core-shell-type nanoparticles composed of poly(?-benzyl-L-glutamate) and poly(ethylene oxide)

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