Evaluation of biodegradable microspheres prepared by a solvent evaporation process using sodium oleate as emulsifier

Fong, J. W.; Nazareno, J.P.; Pearson, Jane E.; Maulding, H.V.

doi:10.1016/0168-3659(86)90072-6

Cited by 50 publications

(10 citation statements)

References 8 publications

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“…The microspheres obtained following the standard protocol had a diameter of approximately 30 µm and the encapsulation efficiency for BSA was approximately 7 % (C-1 ; Table 2). The encapsulation efficiency is in good agreement with the low encapsulation efficiency reported elsewhere (Fong et al 1986 ;Wang et al 1991 ;Atkins 1997). We therefore focussed on improving the encapsulation efficiency by systematically changing the critical parameters in the encapsulation protocol.…”

Section: Optimization Of Processing Parameters In the Encapsulation Osupporting

confidence: 81%

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Encapsulation of bovine serum albumin in poly(lactide-co-glycolide) microspheres by the solid-in-oil-in-water technique

Castellanos

Carrasquillo

López

et al. 2001

Journal of Pharmacy and Pharmacology

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Non-aqueous protocols to encapsulate pharmaceutical proteins into biocompatible polymers have gained much attention because they allow for the minimization of procedure-induced protein structural perturbations. The aim of this study was to determine if these advantages could be extended to a semi-aqueous encapsulation procedure, namely the solid-in-oil-in-water (s/o/w) technique. The model protein bovine serum albumin (BSA) was encapsulated into poly(lactide-co-glycolide) (PLG) microspheres by first suspending lyophilized BSA in methylene chloride containing PLG, followed by emulsification in a 1% aqueous solution of poly(vinyl alcohol). By variation of critical encapsulation parameters (homogenization intensity, BSA:PLG ratio, emulsifier concentration, ratio of organic to aqueous phase) an encapsulation efficiency of > 90% was achieved. The microspheres obtained showed an initial burst release of < 20%, a sustained release over a period of about 19 days, and a cumulative release of at least 90% of the encapsulated BSA. Different release profiles were observed when using different encapsulation protocols. These differences were related to differences in the microsphere erosion observed using scanning electron microscopy. Release of BSA was mainly due to simple diffusion or to both diffusion and microsphere erosion. Fourier-transform infrared studies were conducted to investigate the secondary structure of BSA during the encapsulation. Quantification of the alpha-helix and beta-sheet content as well as of overall structural changes showed that the secondary structure of encapsulated BSA was not more perturbed than in the lyophilized powder used initially. Thus, the encapsulation procedure did not cause detrimental structural perturbations in BSA. In summary, the results demonstrate that the s/o/w technique is an excellent alternative to the water-in-oil-in-water technique, which is still mainly used in the encapsulation of proteins in PLG microspheres.

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Section: Optimization Of Processing Parameters In the Encapsulation Osupporting

confidence: 81%

“…One problem hampering the use of the s\o\w technique is the frequently low encapsulation efficiency achieved (Fong et al 1986 ;Wang et al 1991 ;Atkins 1997). For example, Atkins (1997) reported an efficiency of only up to 14.5 % when encapsulating BSA into various polymers using the s\o\w method.…”

Section: Introductionmentioning

confidence: 99%

Encapsulation of bovine serum albumin in poly(lactide-co-glycolide) microspheres by the solid-in-oil-in-water technique

Castellanos

Carrasquillo

López

et al. 2001

Journal of Pharmacy and Pharmacology

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“…Sodium caprylate and sodium laurate, which are soluble in water at room temperature, were used. In studies by Fong et al,16 fatty acid salts such as sodium oleate did not elicit abnormal tissue response when used as emulsifiers. Sodium caprylate and sodium laurate were not used as emulsifiers in this experiment but were used as additives to increase the entrapment ratio.…”

Section: Resultsmentioning

confidence: 99%

Preparation of Neurotensin Analogue-Containing Poly(dl-lactic acid) Microspheres Formed by Oil-in-Water Solvent Evaporation

Yamakawa

Tsushima

Machida

et al. 1992

Journal of Pharmaceutical Sciences

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“…Although several studies have focused on microencapsulation by using di erent protective colloids (Lin et al 1985, Fong et al 1986, Sato et al 1988, Bodmeier and McGinity 1987, Sprockel and Prapaitrakul 1990, Sjostrom et al 1993, there has been scant study to investigate the e ect of the protective colloids on the crystallinity and polymorphism of the encapsulated drug and wall-forming polymer in microspheres or microcapsules.…”

Section: Introductionmentioning

confidence: 99%

Effect of protective colloids on the induction of polymorphic changes in indomethacin agglomerates after solvent evaporation from o/w emulsions

Lin¹

1999

Journal of Microencapsulation

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Indomethacin (IMC) agglomerates were prepared by the solvent evaporation process from o/w emulsions containing different protective colloids in the external aqueous solution. The types of protective colloids inducing the polymorphic transformation of IMC in the agglomerates without wall material were investigated. The composition and its polymorphs were evaluated from the X-ray diffraction patterns, IR spectra and DSC thermograms. The results indicate that when pectin, beta-cyclodextrin, sodium alginate or sodium dodecyl supphase acted as a protective colloid, the respective IMC agglomerates consisted only of the alpha form of IMC. When gelatin or hydroxypropyl methylcellulose was used as a protective colloid, the amorphous, alpha and gamma forms as well as methylene chloride solvates of IMC were found in the IMC agglomerates. There was only methylene chloride solvate of IMC with a small amount of amorphous form in the IMC agglomerates prepared from albumin as a protective colloid, while IMC agglomerates prepared from methylcellulose, polyvinyl alcohol or biosoluble polymer consisted of the mixture of amorphous and alpha forms, and methylene chloride solvate of IMC. When polyvinyl pyrrolidone was applied to act as a protective colloid, the mixture of methylene chloride solvate and gamma form of IMC with less quantity of amorphous form was found in its IMC agglomerates. This strongly suggests that the composition of IMC agglomerates prepared from the solvent evaporation process was significantly influenced by the type of protective colloids used.

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Evaluation of biodegradable microspheres prepared by a solvent evaporation process using sodium oleate as emulsifier

Cited by 50 publications

References 8 publications

Encapsulation of bovine serum albumin in poly(lactide-co-glycolide) microspheres by the solid-in-oil-in-water technique

Encapsulation of bovine serum albumin in poly(lactide-co-glycolide) microspheres by the solid-in-oil-in-water technique

Preparation of Neurotensin Analogue-Containing Poly(dl-lactic acid) Microspheres Formed by Oil-in-Water Solvent Evaporation

Effect of protective colloids on the induction of polymorphic changes in indomethacin agglomerates after solvent evaporation from o/w emulsions

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