Novel drug release profiles from micellar solutions of PLA–PEO–PLA triblock copolymers

Agrawal, Saumya; Sanabria-DeLong, Naomi; Coburn, Jeannine M.; Tew, Gregory N.; Bhatia, Surita R.

doi:10.1016/j.jconrel.2005.12.024

Cited by 108 publications

(99 citation statements)

References 33 publications

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“…Agrawal et al reported that the crystallinity of the PLA core greatly affects the release of incorporated drugs [32]. They compared the micelles of poly(DL-lactic acid)-DLLA-PEG-poly(DLlactic acid) (amorphous core) with the micelles of PLLA-PEG-PLLA (crystal core).…”

Section: Crystallinitymentioning

confidence: 99%

Size-Controlled Nanomicelles of Poly(lactic acid)–Poly(ethylene glycol) Copolymers with a Multiblock Configuration

et al. 2015

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Abstract:The ability to control the micelle size of poly(lactic acid) and poly(ethylene glycol) (PLA-PEG) block copolymers is important for controlling their circulation in blood cell recognition, drug release and therapeutic effects. We successfully controlled the micelle size by changing the block number of copolymers (multiblock index). PLA-PEG multiblock copolymers with multiblock indexes ranging from 1.35 to 2.78 were synthesized by direct polycondensation with tin chloride/p-toluenesulfonic acid binary catalysts, using PEG with a molecular weight (Mw) of 3200 Da. The Mw of PLA-PEG copolymers increased with an increase in the multiblock index, while micelle size, measured by dynamic light scattering, decreased greatly from 349 to 28 nm. In addition, the X-ray diffraction peak of the PLA crystal disappeared when the multiblock index was increased. These results indicate that a multiblock structure is useful for controlling micelle size without changing the PLA/PEG composition or PEG molecular weight, which strongly influences other micelle features.

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Section: Crystallinitymentioning

confidence: 99%

Size-Controlled Nanomicelles of Poly(lactic acid)–Poly(ethylene glycol) Copolymers with a Multiblock Configuration

et al. 2015

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“…10 Partial miscibility with phase domains in blends of PEO with PLLA of high molecular weight has been claimed. 6,7 Reportedly, blending PEO with PLLA can further enhance the biocompatibility of PLLA; 11,12 however, separate domains in both the amorphous and crystalline domains in PEO/PLLA might make it complicated to addressing the biocompatibility.…”

Section: Introductionmentioning

confidence: 99%

Lamellar orientation and interlamellar cracks in co-crystallized poly(ethylene oxide)/poly(L-lactic acid) blend

Hsieh

Nurkhamidah

Woo

2011

Polym J

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The correlation between the lamellar orientation in ring-banded spherulites and crack patterns in blends of two crystalline polymers crystallized in two steps was investigated. The two polymers were poly(ethylene oxide) (PEO) and poly(L-lactic acid) (PLLA) with a low molecular weight. The techniques used for this investigation included polarizing light optical microscopy, scanning electron microscopy and atomic force microscopy. Crack formation was influenced by the ring band patterns in PLLA and overlapping or impingement between PEO spherulites upon cooling. By extracting the water-soluble PEO from the PEO/PLLA blend, the inner morphology of the lamellar textures was further revealed to have a complex pattern. It consisted of the outer macro-lamellae with a flat-on width of 20 lm and twisting micro-lamellae with a 1-2 lm edge-on width. As the excess PEO was etched off from the valley and the interlamellar crevices of the PLLA lamellae, the outer macro-lamellae plates (B20 lm flat-on width) exhibited up and down periodicity with flat-on orientation. However, the micro-lamellae (with 1-2 lm edge-on width) with twisting were visible inside the cracks. Similar analysis of a PEO-rich composition, PEO/PLLA (80/20) blend with irregular ring bands and no cracks, revealed that the outer macro-lamellae were not present. However, all micro-lamellae twists in the ridge regions irregularly protrude out to create zig-zag banding.

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“…11) Agrawal et al reported that the breakage of the drug-polymer interaction may be a much slower step as compared to the diffusion of drug substance through the polymer network 11) so nearly zero order release may be observed up to approximately 60% in the dissolution profile. In the present study, particles with a diameter of approximately 100 µm, which improved solubility, could be obtained readily using a complex fluidized-bed granulator equipped with a particle-sizing mechanism.…”

Section: Methodsmentioning

confidence: 99%

Preparation of Fine Particles with Improved Solubility Using a Complex Fluidized-Bed Granulator Equipped with a Particle-Sizing Mechanism

Hosaka¹,

Okamura²,

Tokunaga³

2016

CHEMICAL & PHARMACEUTICAL BULLETIN

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A new type of fluidized-bed granulator equipped with a particle-sizing mechanism was used for the preparation of fine particles that improved the solubility of a poorly water-soluble drug substance. Cefteram pivoxyl (CEF) was selected as a model drug substance, and its solution with a hydrophilic polymer, hydroxypropyl cellulose (HPC-L), was sprayed on granulation grade lactose monohydrate (Lac). Three types of treated particles were prepared under different conditions focused on the spraying air pressure and the amount of HPC-L. When the amount of HPC-L was changed, the size of the obtained particles was similar. However, particle size distribution was dependent on the amount of HPC-L. Its distribution became more homogenous with greater amounts of HPC-L, but the particle size distribution obtained by decreasing the spraying air pressure was not acceptable. By processing CEF with HPC-L using a complex fluidized-bed granulator equipped with a particle-sizing mechanism, the dissolution ratio was elevated by approximately 40% compared to that of unprocessed CEF. Moreover, in the dissolution profile of treated CEF, the initial burst was suppressed, and nearly zero order release was observed up to approximately 60% in the dissolution profile. This technique may represent a method with which to design fine particles of approximately 100 µm in size with a narrow distribution, which can improve the solubility of a drug substance with low solubility.Key words fine particle; particle size distribution; dissolution; complex fluidized-bed granulator Recently, techniques that can increase the dissolution ratio or its rate have become a focus of attention since many drugs with low water-solubility are being developed. One method to improve these drugs is to treat drug substances with hydrophilic polymers. The spray-drying technique is a well-known method for the improvement of solubility.1) The advantage of this method is that the particle size of the powder obtained can be controlled in a single step.2) However, pharmaceutical companies encounter several problems, such as the need for new equipment (especially at a commercial scale) and patent or license problems. On the other hand, the approach of spraying a solution or dispersion containing drug substance and hydrophilic polymer on cellulose-based beads using a rotating fluidized-bed granulator is a more practical method. In this case, considering the size of cellulose-based beads, the particle size obtained would be over 200 µm so that the size of tablets containing them tends to be large.3) To obtain fine particles of approximately 100 µm in size, reduction in the size of the core particle is needed. At this time, however, the production of agglomerate particles may be a problem when using a conventional rotating fluidized-bed granulator.4) To suppress their production, a new type of fluidized-bed granulator equipped with a particle-sizing mechanism, referred to as a complex fluidized-bed granulator, has been developed. 5)Few studies in the pharmaceutical field have bee...

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Novel drug release profiles from micellar solutions of PLA–PEO–PLA triblock copolymers

Cited by 108 publications

References 33 publications

Size-Controlled Nanomicelles of Poly(lactic acid)–Poly(ethylene glycol) Copolymers with a Multiblock Configuration

Size-Controlled Nanomicelles of Poly(lactic acid)–Poly(ethylene glycol) Copolymers with a Multiblock Configuration

Lamellar orientation and interlamellar cracks in co-crystallized poly(ethylene oxide)/poly(L-lactic acid) blend

Preparation of Fine Particles with Improved Solubility Using a Complex Fluidized-Bed Granulator Equipped with a Particle-Sizing Mechanism

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