Preparation and Characterization of Polylactic Acid Microspheres Containing Water-Soluble Anesthetics with Small Molecular Weight.

Uchida, Takahiro; Yoshida, Kazushi; Nakada, Yoichi; Nagareya, Noriko; Konishi, Yuriko; Nakai, Aki; Nishikata, Mayumi; Matsuyama, Kenji

doi:10.1248/cpb.45.513

Cited by 18 publications

(11 citation statements)

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“…Inclusion of electrolytes in the external aqueous phase of multiple emulsions is a commonly used approach to enhance the encapsulation of such drugs in hydrophobic polymer MSs. This has been reported for barbiturate salts,29 clodronate sodium,30 and disodium norcantharidate 31. However, inclusion of KCl up to 2% (w/v) in the external aqueous phase of the multiple emulsion in the present study did not enhance VRP loading.…”

Section: Resultssupporting

confidence: 68%

“…2a). Poor entrapment of hydrophilic drugs in hydrophobic matrix MSs has been reported repeatedly 29–31. Inclusion of electrolytes in the external aqueous phase of multiple emulsions is a commonly used approach to enhance the encapsulation of such drugs in hydrophobic polymer MSs.…”

Section: Resultsmentioning

confidence: 97%

“…However, inclusion of KCl up to 2% (w/v) in the external aqueous phase of the multiple emulsion in the present study did not enhance VRP loading. Similarly, 10% (w/v) NaCl failed to enhance the loading of the hydrochloride salts procaine HCl, lidocaine HCl, and dibucaine HCl in PLA MSs when a pH 5 buffer was used as the continuous aqueous phase 29. Inclusion of electrolytes as a physical barrier to drug escape may not be a general approach to enhance the loading of drug salts into polymer MSs.…”

Section: Resultsmentioning

confidence: 98%

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Multivariate modeling of encapsulation and release of an ionizable drug from polymer microspheres

El-Khordagui

Molokhia²,

Ghaly

2009

Journal of Pharmaceutical Sciences

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Section: Resultssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 98%

See 1 more Smart Citation

Multivariate modeling of encapsulation and release of an ionizable drug from polymer microspheres

El-Khordagui

Molokhia²,

Ghaly

2009

Journal of Pharmaceutical Sciences

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“…17,25 In this study, sodium chloride was first added to the inner phase to make the sodium cromoglycate less soluble. Also, the properties of the outer phase were affected by adding sodium chloride to the outer phase.…”

Section: Salt Additionmentioning

confidence: 99%

Improved entrapment efficiency of hydrophilic drug substance during nanoprecipitation of poly(I)lactide nanoparticles

et al. 2004

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ABSTRACTated for the controlled release of pharmacologically active substances.1-6 Micro-and nanoparticle formulations of these polymers have been formulated with various methodologies.7-10 Fessi and coworkers 11 managed to efficiently capsulate drug substances inside nanocapsules by a nanoprecipitation method. Later it was observed that the entrapment of hydrophilic drug substances inside the polymer capsules is a very difficult task using the nanoprecipitation method. 8,12,13 The reason for this difficulty is that the hydrophilic drug substances have very low affinity to the polymer. In addition, the interactions between the polymer and drug are weak, and the drug substance has a tendency to move from the organic phase to the outer aqueous phase and not in the precipitating nanoparticles.The purpose of this research was to improve the entrapment efficiency of a model hydrophilic drug substance, sodium cromoglycate, loaded inside polylactic acid nanoparticles by a modified nanoprecipitation method. The effect of formulation parameters was studied to improve the entrapment efficiency of the drug substance inside the nanoparticles. Several parameters (changes in the amount of model drug, solvent selection, electrolyte addition, pH alteration) were tested in order to increase the loading of the hydrophilic drug in the hydrophobic nanoparticles. Lowering of the pH was the most efficient way to increase the drug loading; up to approximately 70% of the sodium cromoglycate used in the particle formation process could be loaded inside the particles. The loading efficiency without the pH change was around 10% to 15% at maximum. The crystallinity values and crystal habits of the sodium cromoglycate nanoparticles were studied (x-ray diffraction) before and after the lowering of the pH. The change in pH conditions during the nanoprecipitation process did not affect markedly the crystallinity properties of the drug substance. According to this study, it is possible to improve the entrapment efficiency of hydrophilic sodium cromoglycate inside of the nanoparticles by small changes in the process parameters without alterations in the physical properties of the original drug substance.The purpose of this study was to increase the entrapment efficiency of hydrophilic sodium cromoglycate into poly(l)lactide nanoparticles. The model drug, sodium cromoglycate, acts as a preventive reducer of bronchoconstriction in the lungs. The entrapment efficiency was modified by changes in the solvent selection, the amount of the model drug substance (sodium cromoglycate), solvent selection, the pH values of the outer and inner phases, and, finally, by the addition of salt to the aqueous phases. The stability of the drug substance after the most successful drug loadings was studied by x-ray diffraction methods. MATERIALS AND METHODS

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“…proteins) is often limited [1]. This frequently results in poor encapsulation and a large “burst” release of the encapsulated drug within the first few hours or days [1–3]. This initial burst is due to desorption of surface associated hydrophilic molecules on devices comprised of hydrophobic polymers, not polymer degradation [1].…”

Section: Introductionmentioning

confidence: 99%

Functionalized poly(lactic-co-glycolic acid) enhances drug delivery and provides chemical moieties for surface engineering while preserving biocompatibility

et al. 2009

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Poly(lactic-co-glycolic acid) (PLGA) is one of the more widely used polymers for biomedical applications. Nonetheless, PLGA lacks chemical moieties that facilitate cellular interactions and surface chemistries. Furthermore, incorporation of hydrophilic molecules is often problematic. The integration of polymer functionalities would afford the opportunity to alter device characteristics, thereby enabling control over drug interactions, conjugations, and cellular phenomena. In an effort to introduce amine functionalities and improve polymer versatility, we synthesized two block copolymers (PLGA-PLL 502H and PLGA-PLL 503H) comprised of PLGA and Poly(ε-carbobenzoxy-L-lysine) utilizing dicyclohexyl carbodiimide (DCC) coupling. PLGA-PLL micropsheres encapsulated approximately six-fold (502H) and three-fold (503H) more vascular endothelial growth factor (VEGF), and 41% (503H) more ciliary neurotrophic factor (CNTF) than their PLGA counterparts. While the amine functionalities were amenable to the delivery of large molecules and surface conjugations, they did not comprise polymer biocompatibility. With the versatile combination of properties, biocompatibility, and ease of synthesis, these block copolymers have the potential for diverse utility in the fields of drug delivery and tissue engineering.

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Preparation and Characterization of Polylactic Acid Microspheres Containing Water-Soluble Anesthetics with Small Molecular Weight.

Cited by 18 publications

References 0 publications

Multivariate modeling of encapsulation and release of an ionizable drug from polymer microspheres

Multivariate modeling of encapsulation and release of an ionizable drug from polymer microspheres

Improved entrapment efficiency of hydrophilic drug substance during nanoprecipitation of poly(I)lactide nanoparticles

Functionalized poly(lactic-co-glycolic acid) enhances drug delivery and provides chemical moieties for surface engineering while preserving biocompatibility

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