The formulation and stability of multiple emulsions

Florence, Alexander T.; Whitehill, D

doi:10.1016/0378-5173(82)90080-1

Cited by 265 publications

(160 citation statements)

References 24 publications

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“…This may either result in swelling or shrinkage of internal droplets depending on the direction of osmotic gradient. 23) Forced by osmotic pressure gradient, water molecules in the outer aqueous phase might be diffused into the inner aqueous phase resulting in swelling of internal aqueous droplet. The w/o/w emulsion might be destabilized with increase in volume of inner aqueous phase and this might lead to poor entrapment of gentamicin.…”

Section: Resultsmentioning

confidence: 99%

Formulation Optimization of Gentamicin Loaded Eudragit RS100 Microspheres Using Factorial Design Study

Singh

Saraf

Dixit

et al. 2008

Biological & Pharmaceutical Bulletin

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Gentamicin-Eudragit RS100 microspheres were prepared by modified double emulsion method. A 3 2 full factorial experiment was designed to study the effects of the composition of outer aqueous phase in terms of amount of glycerol (viscosity effect) and sodium chloride (osmotic pressure gradient effect) on the entrapment efficiency and % yield and microsphere size. The results of analysis of variance test for responses measured indicated that the test is significant (pϾ0.05). The contribution of sodium chloride concentration was found to be higher on entrapment efficiency and % yield, whereas glycerol produced significant effect on the mean diameter of microspheres. Microspheres demonstrated spherical particles in the size range of 33.24-60.43 m mm. In vitro release profile of optimized formulation demonstrated sustained release for 24 h following Higuchi kinetics. Finally, drug bioactivity was found to remain intact after microencapsulation. Response surface graphs are presented to examine the effects of independent variables on the responses studied. Thus, by formulation design important parameters affecting formulation characteristics of gentamicin loaded Eudragit RS100 microspheres can be identified for controlled delivery with desirable characters in terms of maximum entrapment and yield.

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Section: Resultsmentioning

confidence: 99%

Formulation Optimization of Gentamicin Loaded Eudragit RS100 Microspheres Using Factorial Design Study

Singh

Saraf

Dixit

et al. 2008

Biological & Pharmaceutical Bulletin

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“…From a theoretical standpoint, such double emulsion systems are too complex for any reasonable estimate of repulsive and attractive force to apply the Derjaguin, Landau, Verwey and Overbeek (DLVO) theory. 27,30 More mechanistic studies involving techniques such as droplet size determination, transmission microscopy-freeze fracture electron microscopy (FFEM), small angle X-ray scattering (SAXS), small angle neutron scattering (SANS), static light scattering (SLS) or intensity light scattering (ILS), dynamic light scattering (DLS), electrophoretic light scattering (ELS), and rheological and chemometric determination of micelle formations 31 will be required to confirm or optimize these preliminary results. Figure 6.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of sucrose esters as alternative surfactants in microencapsulation of proteins by the solvent evaporation method

2003

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KEYWORDS: proteins, microencapsulation, solvent evaporation, sucrose ester, surfactants Sucrose esters (SE) are surfactants with potential pharmaceutical applications because of their low toxicity, biocompatibility, and excellent biodegradability. The objective of the study was to investigate SE as alternative surfactants in stabilizing emulsions for the preparation of protein-loaded microparticles. To achieve this goal, using bovine serum albumin as model protein and 75/25 poly(d,l-lactide-co-glycolide) as polymer carrier, we have investigated the influence of the following formulation variables on particle characteristics: (1) SE concentration from 0.01% to 1% (wt/vol), (2) hydrophile-lipophile balance (HLB) value of SE from 6 to 15, and (3) the nature of emulsion stabilizer. The formulations were characterized using ATR-FTIR spectroscopy, bicinchoninic acid protein assay, optical microscopy and SDS-PAGE. Results showed that at 0.05% (wt/vol) surfactant concentration, SE with HLB of 6 to 15 provided discrete and spherical microparticles with the highest encapsulation efficiency compared with controls polyvinyl alcohol (PVA) and poloxamer 188. These results may be explained by the difference in critical micelle concentration, diffusion, and partition coefficient among the tested surfactants. HLB values were consistent with SE spectral data. The protein molecular weight was preserved after the encapsulation process. The effective SE concentration was far less (20-to 200-fold) than that is usually required for PVA in microencapsulation of proteins. However, the encapsulation efficiency was relatively lower (~13.5%). These preliminary results suggest that it may be desirable to optimize such formulations in vitro and in vivo for SE to be eventually used as alternative surfactants in the development of microparticulate systems for parenteral delivery of protein and gene medicines.

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“…In two-step procedure, firstly W/O emulsion is prepared with a low HLB value surfactant(s) by high energy mixing or homogenization and then this emulsion is dispersed in an aqueous phase containing high HLB value surfactant but this time with relatively low energy mixing [83][84][85].…”

Section: Hydrophilic-lipophilic Balance (Hlb) Conceptmentioning

confidence: 99%