"The microemulsion concept was introduced as early as the 1940s by Hoar and Schulman55 who generated a clear single-phase solution by titrating a milky emulsion with hexanol. A microemulsion is defined as a system of water, oil, and amphiphile, which is a single optically isotropic and thermodynamically stable liquid solution. "
[Show abstract][Hide abstract] ABSTRACT: Although many agents have therapeutic potentials for central nervous system (CNS) diseases, few of these agents have been clinically used because of the brain barriers. As the protective barrier of the CNS, the blood-brain barrier and the blood-cerebrospinal fluid barrier maintain the brain microenvironment, neuronal activity, and proper functioning of the CNS. Different strategies for efficient CNS delivery have been studied. This article reviews the current approaches to open or facilitate penetration across these barriers for enhanced drug delivery to the CNS. These approaches are summarized into three broad categories: noninvasive, invasive, and miscellaneous techniques. The progresses made using these approaches are reviewed, and the associated mechanisms and problems are discussed.
International Journal of Nanomedicine 05/2014; 9(1):2241-2257. DOI:10.2147/IJN.S61288 · 4.38 Impact Factor
"MEs are thermodynamically stable-phase transition systems, which possess low surface tension and small droplet size (5–200 nm), which may result in high drug absorption and permeation, and hence, strong possibility of drug delivery to the posterior segment of the eye. The term ME was first coined by Hoar and Schulman in 1943 . Scientifically, a ME is a system of water, oil, and an amphiphile, frequently in combination with a cosurfactant, which is a single optically isotropic and thermodynamically stable liquid solution . "
[Show abstract][Hide abstract] ABSTRACT: Delivery of drugs into eyes using conventional drug delivery systems, such as solutions, is a considerable challenge to the treatment of ocular diseases. Drug loss from the ocular surface by lachrymal fluid secretion, lachrymal fluid-eye barriers, and blood-ocular barriers are main obstacles. A number of ophthalmic drug delivery carriers have been made to improve the bioavailability and to prolong the residence time of drugs applied topically onto the eye. The potential use of microemulsions as an ocular drug delivery carrier offers several favorable pharmaceutical and biopharmaceutical properties such as their excellent thermodynamic stability, phase transition to liquid-crystal state, very low surface tension, and small droplet size, which may result in improved ocular drug retention, extended duration of action, high ocular absorption, and permeation of loaded drugs. Further, both lipophilic and hydrophilic characteristics are present in microemulsions, so that the loaded drugs can diffuse passively as well get significantly partitioned in the variable lipophilic-hydrophilic corneal barrier. This review will provide an insight into previous studies on microemulsions for ocular delivery of drugs using various nonionic surfactants, cosurfactants, and associated irritation potential on the ocular surface. The reported in vivo experiments have shown a delayed effect of drug incorporated in microemulsion and an increase in the corneal permeation of the drug.
"In micro-emulsions, the interfacial tension is so low that the interfacial energy assumes a similar or lower value than the entropy of dispersion. This renders the free energy zero or negative [28,29]. The use of only one surfactant may hardly achieve transient negative interfacial tension and fluid interfacial film; hence the need for incorporation of a co-surfactant . "
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: CSIC (5-chloro-3-phenylsulfonylindole-2-carboxamide), a non-nucleoside reverse transcriptase inhibitor (NNRTI) has not been advanced as a therapeutic anti-HIV candidate drug due to its low aqueous solubility and poor bioavailability. OBJECTIVE: The objective of this work was to formulate CSIC into self-emulsifying oil formulations for the purpose of improving its aqueous solubility and evaluating in vitro antiretroviral activity. METHODS: CSIC self-emulsifying oil formulations (SEFs) were formulated and evaluated for droplet size, zeta potential, polydispersity index (PDI), viscosity, emulsification time, stability and bioactivity studies. RESULTS: Results showed significantly improved solubility of CSIC in the SEFs.The concentration of co-surfactant affected the droplet size, zeta potential and polydispersity index. In vitro bioactivity studies showed that the CSIC SEFs retained full anti-HIV activity. CONCLUSION: The in vitro data from this first attempt to formulate CSIC SEFs suggest that improvement of the aqueous solubility of CSIC through this delivery system may accentuate its antiretroviral effectiveness in vivo via bioavailability enhancement. The formulation is therefore intended as an oral anti-HIV agent for prophylactic and therapeutic uses.
AIDS Research and Therapy 05/2013; 10(1):14. DOI:10.1186/1742-6405-10-14 · 1.46 Impact Factor
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