Zero-order release from biphasic polymer hydrogels

Varelas, C. G.; Dixon, David G.; Steiner, Carol A.

doi:10.1016/0168-3659(94)00085-9

Cited by 230 publications

(123 citation statements)

References 13 publications

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“…Squared correlation coefficients (R 2 ) obtained with the Zero-order model was 0.9706. This model can be used to describe the drug release from several types of delivery systems such as matrix tablets for drugs with low solubility 32 and osmotic systems, where drug release would be directly proportional at time. First-order kinetics 33,34 gave a R 2 of 0.9815.…”

Section: X-rays Diffraction Profile Obtained From Naproxen (A) Empmentioning

confidence: 99%

Encapsulation of naproxen in nanostructured system: structural characterization and in vitro release studies

Mello¹,

Ricci-Júnior²

2011

Quím. Nova

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Recebido em 7/6/10; aceito em 10/1/11; publicado na web em 25/3/11 Nanoparticles were produced by solvent emulsification evaporation method with the following characteristics: nanometric size (238 ± 3 nm), narrow polydispersity index (0.11), negative zeta potential (-15.1 mV), good yield of the process (73 ± 1.5%), excellent encapsulation efficiency (81.3 ± 4.2%) and spherical shape. X-rays diffraction demonstrated the loss of drug crystallinity after encapsulation; however, the profile of the diffractograms of the poly-ε-caprolactone (PCL) nanoparticles was kept. Differential scanning calorimetry thermograms, correspondingly, exhibited the loss of drug melting peak and the increasing of the melting point of the PCL nanoparticles, evidencing an interaction drug-polymer. Naproxen release was low and sustained obeying the Higuchi´s kinetic. The results show that nanoparticles are promising sustained release system to the naproxen.

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Section: X-rays Diffraction Profile Obtained From Naproxen (A) Empmentioning

confidence: 99%

Encapsulation of naproxen in nanostructured system: structural characterization and in vitro release studies

Mello¹,

Ricci-Júnior²

2011

Quím. Nova

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“…A nonhomogeneous distribution of drug is accounted for in a drug-release model proposed by Varelas et al, but the polymer matrix does not erode. 28,29 In this model, isolated domains act as reservoirs from which drug diffuses through a polymer matrix. We have developed a model for erosion and drug release that accounts for microphase-separated domains that erode at different rates and for partitioning of encapsulated drugs within the phase-separated domains.…”

Section: Introductionmentioning

confidence: 99%

Molecular Description of Erosion Phenomena in Biodegradable Polymers

Kipper

Narasimhan

2005

Macromolecules

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A new model for the erosion kinetics of semicrystalline surface-erodible homopolymers and copolymers is presented. The model is derived for a class of surface-erodible polyanhydride copolymers, with the goal of describing erosion in terms of fundamental, elementary processes. This model is based on an accurate description of copolymer microstructure and can thereby account for the heterogeneous erosion due to microphase separation and crystallinity. In addition to accurately predicting the overall erosion profile and the release of individual monomer species, several key phenomena that occur during erosion are described. These include precipitation of slightly soluble degradation products inside the pores of the erosion zone and pH changes during erosion due to dissolution of acidic monomers and the consequent changes in monomer solubility. This model also motivates future experiments to investigate predicted phenomena such as the effects due to local changes in pH and degradation rate constants for crystalline and amorphous moieties. The rational design of biomedical devices such as vehicles for drug delivery and scaffolds for tissue engineering will be aided by the application of this model and future extensions of it. Received November 13, 2004; Revised Manuscript Received December 13, 2004 ABSTRACT: A new model for the erosion kinetics of semicrystalline surface-erodible homopolymers and copolymers is presented. The model is derived for a class of surface-erodible polyanhydride copolymers, with the goal of describing erosion in terms of fundamental, elementary processes. This model is based on an accurate description of copolymer microstructure and can thereby account for the heterogeneous erosion due to microphase separation and crystallinity. In addition to accurately predicting the overall erosion profile and the release of individual monomer species, several key phenomena that occur during erosion are described. These include precipitation of slightly soluble degradation products inside the pores of the erosion zone and pH changes during erosion due to dissolution of acidic monomers and the consequent changes in monomer solubility. This model also motivates future experiments to investigate predicted phenomena such as the effects due to local changes in pH and degradation rate constants for crystalline and amorphous moieties. The rational design of biomedical devices such as vehicles for drug delivery and scaffolds for tissue engineering will be aided by the application of this model and future extensions of it.

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“…As reported (Varelas, Dicon, Stediner, 1995), these models fit hydrophilic matrix systems containing poorly watersoluble drugs. In addition, the value of the release exponent n in the Korsmeyer-Peppas model approached a value of one, which corresponds to a case II transport mechanism, where drug release is predominately controlled by polymer relaxation and erosion.…”

Section: Resultsmentioning

confidence: 99%

In vitro evaluation of sustained released matrix tablets containing ibuprofen: a model poorly water-soluble drug

Guerra-Ponce

Gracia-Vásquez

González-Barranco

et al. 2016

Braz. J. Pharm. Sci.

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A matrix system was developed that releases ibuprofen (IB) over a 12-hour period and the influence of the polymer type and concentration on the release rate of the drug was evaluated. Tablets containing different concentrations of Carbopol (CP), hydroxypropyl methylcellulose (HPMC), or ethyl cellulose (EC) were prepared using direct compression and the drug content, content uniformity, hardness, friability, dissolution performance, and in vitro release kinetics were examined. Formulated tablets were found to be within acceptable limits for physical and chemical parameters. The release kinetics of the Carbopol®971P 8% formulation showed the best linearity (r 2 =0.977) in fitting zero-order kinetics, suggesting the release rate was time independent. The drug release from tablets containing 8% CP was extended over approximately 18 hours and the release kinetics were nearly linear, suggesting that this system has the potential to maintain constant plasma drug concentrations over 12 hours, which could reduce the frequency of administration and the occurrence of adverse effects associated with repeated administration of conventional IB tablets.Uniterms: Ibuprofen/study. Ibuprofen/sustained release tablets. Ibuprofen/formulation/carbopol. Ibuprofen/formulation/hydroxypropyl methylcellulose. Ibuprofen/formulations/ethyl cellulose. Ibuprofen/ formulations/release kinetics.

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Zero-order release from biphasic polymer hydrogels

Cited by 230 publications

References 13 publications

Encapsulation of naproxen in nanostructured system: structural characterization and in vitro release studies

Encapsulation of naproxen in nanostructured system: structural characterization and in vitro release studies

Molecular Description of Erosion Phenomena in Biodegradable Polymers

In vitro evaluation of sustained released matrix tablets containing ibuprofen: a model poorly water-soluble drug

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