Crown ethers are cyclic molecules consisting of a ring containing several ether groups. The most common and important members of this series are 12-crown-4 (12C4), 15-crown-5 (15C5), and 18-crown-6 (18C6). These container molecules have the ability to sequester metal ions, and their complexes with drugs are able to traverse cell membranes. This study investigated 12C4, 15C5, and 18C6 for their ability to increase solubility of ocular drugs and enhance their penetration into the cornea. Phase solubility analysis determined crown ethers' ability to enhance the solubility of riboflavin, a drug used for the therapy of keratoconus, and these solutions were investigated for ocular drug permeation enhancing properties. Atomic absorption spectroscopy demonstrated crown ether solutions' ability to sequester Ca from corneal epithelia, and crown ether mediated adsorption of riboflavin into the stroma was investigated. Induced corneal opacity studies assessed potential toxicity of crown ethers. Crown ethers enhanced riboflavin's aqueous solubility and its penetration into in vitro bovine corneas; the smaller sized crown ethers gave greatest enhancement. They were shown to sequester Ca ions from corneal epithelia; doing so loosens cellular membrane tight junctions thus enhancing riboflavin penetration. Induced corneal opacity was similar to that afforded by benzalkonium chloride and less than is produced using polyaminocarboxylic acids. However, in vivo experiments performed in rats with 12C4 did not show any statistically significant permeability enhancement compared to enhancer-free formulation.
Eudragit ® E PO (EPO) is a terpolymer based on N,N-dimethylaminoethyl methacrylate with methylmethacrylate and butylmethacrylate, produced by Evonik Industries AG as a pharmaceutical excipient. In this work, EPO was chemically modified through reaction with acryloyl chloride. The successful modification of EPO was confirmed by FTIR, NMRspectroscopy, elemental and thermal analysis. The degree of acrylation was determined by permanganatometric titration. The slug mucosal irritation test was used to demonstrate nonirritant nature of EPO and its acrylated derivatives (AEPO). The mucoadhesive properties of EPO and AEPO were evaluated using freshly excised sheep nasal mucosa and it was demonstrated that acrylated polymers facilitated greater retention of sodium fluorescein on mucosal surfaces compared to solution mixture of this dye solution with EPO as well as free dye.
Поступила в редакцию Принята в печать Полиэтиленгликоль (ПЭГ) является водорастворимым полимером с уникальным набором физико-химических и биологических свойств. Данный обзор посвящен использованию ПЭГилирования для дизайна новых лекарственных форм и модификации биомолекул. В частности, рассмотрены особенности ПЭГилированных наночастиц, липосом, белков, ферментов, малых молекул лекарств и полиэлектролитов и их влияние на системную доставку лекарств, а также преодоление различных биологических барьеров и адгезию к слизистым тканям (мукоадгезию).
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