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Lamprecht, Alf; Schäfer, U.; Lehr, Claus‐Michael

doi:10.1023/a:1011032328064

Cited by 444 publications

(137 citation statements)

References 23 publications

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“…Animal models with ulcerative colitis were produced using instillation of TNBS to the colonic parts of rats [19] [20] [22]. Namely, after rats were fasted for 48 h, 0.25 mL of 50% (v/v) aqueous ethanol containing TNBS (20 mg) was instilled to each rat into the colonic part 7 cm from the anus through a catheter.…”

Section: Animal Experimentsmentioning

confidence: 99%

“…Micro-or nano-particles and prodrugs for glucocorticoids have been reported to exhibit enhanced efficacy and reduced toxicities, which are based on the localization of the drug at the diseased site and the reduction of the systemic drug level [19]- [21]. Thus, small size particles (submicron-micron order size) and prolonged release are considered to be important in order to improve the drug function in the treatment of UC [19] [22].…”

Section: Introductionmentioning

confidence: 99%

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Pharmacokinetic Evaluation of Chitosan-Succinyl-Prednisolone Conjugate Microparticles as a Colonic Delivery System: Comparison with Enteric-Coated Conjugate Microparticles

Onishi¹

2014

Health

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In the previous study, chitosan-succinyl-prednisolone conjugate microparticles (MP) were found to exhibit good efficacy and reduced toxicity nearly as well as their Eudragit L-coated microparticles (MP/EuL). This proposes a question whether enteric-coating of MP is necessary or not. Although MP/EuL were already examined for their pharmacokinetic and gastrointestinal behaviors, MP have not been done yet. Therefore, in this study, MP were evaluated by investigating pharmacokinetic features in detail. MP with the in vitro features equivalent to those of the previous conjugate microparticles could be produced more readily in the modified preparative method. Pharmacokinetic and gastrointestinal behaviors of MP were investigated by intragastric dosing (5 mg PD eq./kg) to rats with 2,4,6-trinitrobenzenesulfonic acid-induced ulcerative colitis. The plasma concentration was suppressed extensively in MP as well as MP/EuL, supporting the reduction of PD systemic toxic side effects. However, the plasma level increased gradually up to 7 h in MP, but not in MP/EuL. At 8 h after dosing, MP were detected in the stomach to a fair extent, and free PD was found there, indicating that MP were subjected to trapping in the stomach probably due to positive charge of chitosan molecules. For MP, such prolonged localization and slow release of PD in the stomach were probably associated with the gradual increase in plasma concentration. Therefore, MP/EuL were evaluated to be superior to MP for effective targeting to ulcerative colitis. It is concluded that enteric-coating is very important for the targeting system using MP.

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Section: Animal Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pharmacokinetic Evaluation of Chitosan-Succinyl-Prednisolone Conjugate Microparticles as a Colonic Delivery System: Comparison with Enteric-Coated Conjugate Microparticles

Onishi¹

2014

Health

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“…Therefore, the size-dependent deposition of microparticles and nanoparticles in a model of experimental colitis was examined as a first step in the development of a new selective drug delivery strategy (Lamprecht et al 2001a). An increased adhesion of particles was observed at thicker mucous layers of inflamed tissue while in ulcerated regions a size dependency was shown.…”

Section: Inflammatory Bowel Diseasementioning

confidence: 99%

Targeted drug-delivery approaches by nanoparticulate carriers in the therapy of inflammatory diseases

Ulbrich

Lamprecht

2009

J. R. Soc. Interface.

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149

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Limitations in therapy induced by adverse effects due to unselective drug availability and therefore the use of potentially too high doses are a common problem. One prominent example for this dilemma are inflammatory diseases. Colloidal carriers allow one to improve delivery of drugs to the site of action and appear promising to overcome this general therapeutic drawback. Specific uptake of nanoparticles by immune-related cells in inflamed barriers offers selective drug targeting to the inflamed tissue. Here we focus on nanocarrier-based drug delivery strategies for the treatment of common inflammatory disorders like rheumatoid arthritis, multiple sclerosis, uveitis or inflammatory bowel disease.

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“…Inflammation is a complex cellular event, during which various cytokines are released and excess reactive oxygen species (ROS) are generated by immune cells [5]. Interstitial acidification is commonly associated with the course of inflammatory reactions against pathogenic microorganisms in peripheral tissues, where extracellular pH values as low as 5.5-7.0 have been observed [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Design and Preparation of a Nanoprobe for Imaging Inflammation Sites

Yoshitomi

Nagasaki

2012

Biointerphases

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To image inflammation sites, we developed a novel nanoparticle, hydroxylamine-containing nanoparticle (HANP), which emits an intense electron spin resonance (ESR)-signal triggered by enzymatic oxidation reaction and pH-sensitive self-disintegration. The nanoparticle was prepared from an amphiphilic block copolymer, poly (ethylene glycol)-b-poly[4-(2,2,6,6-tetramethylpiperidine-1-hydroxyl)aminomethylstyrene] (PEG-b-PMNT-H), which spontaneously forms a core-shell type polymeric micelle (particle diameter = ca. 50 nm) in aqueous media. Because the PMNT-H segment in the block copolymer possesses amino groups in each repeating unit, the particle can be disintegrated by protonation of the amino groups in an acidic pH environment such as inflammation sites, which is confined to the hydrophobic core of HANP.Mixing HANP with horseradish peroxidase (HRP)/H 2 O 2 mixture resulted in enzymatic oxidization of the hydroxylamines in the PEG-b-PMNT-H and converted the hydroxylamine to the stable nitroxide radical form in PEGb-poly[4-(2,2,6,6-tetramethylpiperidine-1-oxyl)aminomethylstyrene] (PEG-b-PMNT), which shows an intense ESR signal. It is interesting to note that the ESR signal increased at a greater rate under acidic conditions (pH 5.6) than that under neutral conditions (pH 7.4), although the enzymatic activity of HRP under neutral conditions is known to be much higher than that under acidic conditions. This indicates that enzymatic oxidation reaction was accelerated by synchronizing the disintegration of HANP under acidic conditions. On the basis of these results, HANP can be used as a high-performance ESR probe for imaging of inflammation sites.

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Abstract: The use of submicron-sized carriers holds promise for the targeted delivery of drugs to the inflamed colonic mucosal areas in inflammatory bowel disease.

Cited by 444 publications

References 23 publications

Pharmacokinetic Evaluation of Chitosan-Succinyl-Prednisolone Conjugate Microparticles as a Colonic Delivery System: Comparison with Enteric-Coated Conjugate Microparticles

Pharmacokinetic Evaluation of Chitosan-Succinyl-Prednisolone Conjugate Microparticles as a Colonic Delivery System: Comparison with Enteric-Coated Conjugate Microparticles

Targeted drug-delivery approaches by nanoparticulate carriers in the therapy of inflammatory diseases

Design and Preparation of a Nanoprobe for Imaging Inflammation Sites

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