Characterization and in vitro release of cyclosporine-A from poly(D,L-lactide-co-glycolide implants obtained by solvent/extraction evaporation

Saliba, Juliana Barbosa; Silva-Cunha, Armando; Silva, Gisele Rodrigues da; Yoshida, María Irene; Mansur, Alexandra A.P.; Mansur, Herman S.

doi:10.1590/s0100-40422012000400013

Cited by 6 publications

(4 citation statements)

References 31 publications

(45 reference statements)

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“…These diffractions are consistent with those of the crystalline PEG20k (Figure S3a) and reported PEG segments in PELGA block copolymers, 24 and unlikely associated with poly(D,L-lactide-co-glycolide) segments which tend to be amorphous. 25,26 Meanwhile, the wet PELGA film also gave a diffuse diffraction peak at ∼4.0 Å (Figure S4). This hydration-facilitated PEG crystallization, in addition to microphase separation, has likely contributed to the observed hydration-induced mechanical strengthening of the PELGA film.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Shape Recovery with Concomitant Mechanical Strengthening of Amphiphilic Shape Memory Polymers in Warm Water

Zhang

DeBartolo

Song

2017

ACS Appl. Mater. Interfaces

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Maintaining adequate or enhancing mechanical properties of shape memory polymers (SMPs) after shape recovery in an aqueous environment are greatly desired for biomedical applications of SMPs as self-fitting tissue scaffolds or minimally invasive surgical implants. Here we report stable temporary shape fixing and facile shape recovery of biodegradable triblock amphiphilic SMPs containing a poly(ethylene glycol) (PEG) center block and flanking poly(lactic acid) or poly(lactic-co-glycolic acid) blocks in warm water, accompanied by concomitant enhanced mechanical strengths. Differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WXRD), and small-angle X-ray scattering (SAXS) analyses revealed that the unique stiffening of the amphiphilic SMPs upon hydration was due to hydration-driven microphase separation and PEG crystallization. We further demonstrated that the chemical composition of degradable blocks in these SMPs could be tailored to affect the persistence of hydration-induced stiffening upon subsequent dehydration. These properties combined open new horizons for these amphiphilic SMPs for smart weight-bearing in vivo applications (e.g., as self-fitting intervertebral discs). This study also provides a new material design strategy to strengthen polymers in aqueous environment in general.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Shape Recovery with Concomitant Mechanical Strengthening of Amphiphilic Shape Memory Polymers in Warm Water

Zhang

DeBartolo

Song

2017

ACS Appl. Mater. Interfaces

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“…As mentioned above, direct comparisons with the spectrum of CyA alone may have limitations, but even so, it is of interest to note the changes in the peak position and breadth which may indicate some degree of molecular interaction with the surfactants. In the 1750–1000 cm –1 spectral region of CyA (Figure a), an amide peak shift from 1630 to 1625 cm –1 was observed on loading into micelles, raising the possibility of a hydrogen bonding interaction between the surfactants and the amide group of CyA, supported by the peak broadening observed as well as the change in wavenumber. , A further effect was observed in spectral region 1080–1300 cm –1 with the disappearance of the 1295 and 1265 cm –1 amine peaks of CyA and observation of a new broad peak at 1280 cm –1 . Figure b shows a similar alteration of the amine and alkyl group peaks in the 3300–2800 cm –1 regions.…”

Section: Resultsmentioning

confidence: 93%

Design and Characterization of Cyclosporine A-Loaded Nanofibers for Enhanced Drug Dissolution

Dubey¹,

Barker²,

Craig³

2020

ACS Omega

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Despite widespread use as an immunosuppressant, the therapeutic efficacy of the undecapeptide cyclosporine A (CyA) is compromised when given by the oral route because of the innate hydrophobicity of the drug molecule, potentially leading to poor aqueous solubility and bioavailability. The aim of this study was to develop and characterize nanofibers based on the water-miscible polymer polyvinylpyrrolidone (PVP), incorporating CyA preloaded into polymeric surfactants so as to promote micelle formation on hydration; therefore, this approach represents the novel combination of three dissolution enhancement methodologies, namely solid dispersion technology, micellar systems, and nanofibers with enhanced surface area. The preparation of the nanofibers was performed in two steps. First, mixed micelles composed of the water-soluble vitamin E derivative D-α-tocopheryl poly(ethylene glycol) 1000 succinate and the amphiphilic triblock polymer Pluronic F127 (Poloxamer 407) were prepared. The micelles were characterized in terms of size, surface charge, drug loading, and encapsulation efficiency using transmission electron microscopy, dynamic light scattering, Fourier-transform infrared spectroscopy, high-performance liquid chromatography, and scanning electron and atomic force microscopy analysis. Nanofibers composed of PVP and the drugloaded surfactant system were then prepared via electrospinning, with accompanying thermal, spectroscopic, and surface topological analysis. Dissolution studies indicated an extremely rapid dissolution profile for the fibers compared to the drug alone, while wettability studies also indicated a marked decrease in contact angle compared to the drug alone. Overall, the new approach appears to offer a viable means for considerably improving the dissolution of the hydrophobic peptide CyA, with associated implications for improved oral bioavailability.

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“…For example, when encapsulating risperidone in PLGA microspheres, its EE was as low as 14.4% [ 25 ]. In cases of cyclosporine A and norquetiapine, their EE values were 57.5 ± 3.0% and 48.3 ± 3.0%, respectively [ 26 , 27 ]. There are also a couple of studies encapsulating progesterone into PLGA microspheres via methylene chloride-based solvent evaporation methods [ 28 , 29 ].…”

Section: Resultsmentioning

confidence: 99%

Assessment of Residual Solvent and Drug in PLGA Microspheres by Derivative Thermogravimetry

Shim

Sah

2020

Pharmaceutics

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Thermogravimetry does not give specific information on residual organic solvents in polymeric matrices unless it is hyphenated with the so-called evolved gas analysis. The purpose of this study was to apply, for the first time, derivative thermogravimetry (DTG) to characterize a residual solvent and a drug in poly-d,l-lactide-co-glycolide (PLGA) microspheres. Ethyl formate, an ICH class 3 solvent, was used to encapsulate progesterone into microspheres. DTG provided a distinct peak, displaying the onset and end temperatures at which ethyl formate started to evolve from to where it completely escaped out of the microspheres. DTG also gave the area and height of the solvent peak, as well as the temperature of the highest mass change rate of the microspheres. These derivative parameters allowed for the measurement of the amount of residual ethyl formate in the microspheres. Interestingly, progesterone affected not only the residual solvent amount but also these derivative parameters. Another intriguing finding was that there was a linear relationship between progesterone content and the peak height of ethyl formate. The residual solvent data calculated by DTG were quite comparable to those measured by gas chromatography. In summary, DTG could be an efficient and practical quality control tool to evaluate residual solvents and drugs in various polymeric matrices.

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Characterization and in vitro release of cyclosporine-A from poly(D,L-lactide-co-glycolide implants obtained by solvent/extraction evaporation

Cited by 6 publications

References 31 publications

Shape Recovery with Concomitant Mechanical Strengthening of Amphiphilic Shape Memory Polymers in Warm Water

Shape Recovery with Concomitant Mechanical Strengthening of Amphiphilic Shape Memory Polymers in Warm Water

Design and Characterization of Cyclosporine A-Loaded Nanofibers for Enhanced Drug Dissolution

Assessment of Residual Solvent and Drug in PLGA Microspheres by Derivative Thermogravimetry

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