Drug delivery, surfactants

While most vesicles are formed from double-tail amphiphiles such as lipids, they can also be made from some single chain fatty acids [73], surfactant-cosurfactant mixtures [71], and bola (two-headed) amphiphiles [74]. In addition to the more common spherical shells, tubular vesicles have been observed in DMPC-alcohol mixtures [70]. Polymerizable lipids allow photo- or chemical polymerization that can sometimes stabilize the vesicle [65] however, the structural change in the bilayer on polymerization can cause giant vesicles to bud into smaller shells [76]. Multivesicular liposomes are collections of hundreds of bilayer enclosed water-filled compartments that are suitable for localized drug delivery [77]. The structures of these water-in-water vesicles resemble those of foams (see Section XIV-7) with the polyhedral structure persisting down to molecular dimensions as shown in Fig. XV-11. 

Xylans from beech wood, corncobs, and the alkaline steeping liquor of the viscose process have been shown to be applicable as pharmaceutical auxiliaries [3]. Micro- and nanoparticles were prepared by a coacervation method from xylan isolated from corncobs [150]. The process is based on neutralization of an alkaline solution in the presence of surfactant, which was shown to influence both the particle size and morphology. They are aimed at applications in drug delivery systems. 

Microelectronic circuits for communications. Controlled permeability films for drug delivery systems. Protein-specific sensors for the monitoring of biochemical processes. Catalysts for the production of fuels and chemicals. Optical coatings for window glass. Electrodes for batteries and fuel cells. Corrosion-resistant coatings for the protection of metals and ceramics. Surface active agents, or surfactants, for use in tertiary oil recovery and the production of polymers, paper, textiles, agricultural chemicals, and cement. 

Surfactants and Polymers in Drug Delivery, Martin Malmsten... 

As with micelle-facilitated dissolution, emulsion-facilitated dissolution has gained renewed interest due to its application to water-insoluble drug delivery and enhanced absorption. Over the years, emulsion systems have been developed and used to either model the in vivo dissolution process or mimic the intestinal surfactant system to enhance drug delivery of poorly soluble compounds [54-66], Emulsions have also been used as vehicles for drug delivery, e.g., to protect... 

Nevertheless, there are reports on enhancement of ocular drug absorption by bile salts [33], surfactants [200], and chelators [149], Newton et al. [35] demonstrated that Azone, an enhancer widely tested in transdermal drug delivery [201], increased the ocular absorption of cyclosporine, an immunosuppressant, by a factor of 3, thereby prolonging the survival of a corneal allograft. In 1986, Lee et al. [34] reported that 10 pg/mL cytochalasin B, an agent capable of condensing the actin microfilaments, increased the aqueous humor and iris-ciliary body concentrations of topically applied inulin (5 kDa) by about 70% and 700%, respectively, in the albino rabbit. 

Host-guest systems made from dendritic materials have potential in the areas of membrane transport and drug delivery [68, 84, 85]. In a recent report [136] Tomalia and coworkers investigated structural aspects of a series of PAM AM bolaamphiphiles (e.g., 50) with a hydrophobic diamino do decane core unit. Fluorescence emission of added dye (nile red) was significantly enhanced in an aqueous medium in the presence of 50 unlike the cases when 51 and 52 were added (Fig. 23). Addition of anion surfactants to this mixture generated supramolecular assemblies which enhanced their ability (ca.by 10-fold) to accommodate nile red (53). Further increase in emission was noted by decreasing the pH from the normal value of 11 for PAMAM dendrimers to 7. At lower pH values the... 

Continuous aqueous phase emulsion polymerization is one of the most widely used procedures to make nanoparticles for drug delivery purposes, especially those prepared from the alkylcyanoacrylate monomers. An oil-in-water emulsion system is employed where the monomer is emulsified in a continuous aqueous phase containing soluble initiator and surfactant [39, 40]. Under these conditions, the monomer is partly solubilized in micelles (5-10 nm), emulsified as large... 

W. J. Irwin, K. A Belaid, Drug-Delivery by Ion-Exchange. Stabihty of Ester Prodrugs of Propranolol in Surfactant and Enzymatic Systems , Int. J. Pharm. 1988, 48, 159 — 166. 

Tiemessen, H.L.G.M., Nonionie Surfactant Systems for Transdermal Drug Delivery, Ph.D. Thesis Leiden University, The Netherlands, 1989. 

RME shows particular promise in the recovery of proteins/enzymes [12-14]. In the past two decades, the potential of RME in the separation of biological macromolecules has been demonstrated [15-20]. RMs have also been used as media for hosting enzymatic reactions [21-23]. Martinek et al. [24] were the first to demonstrate the catalytic activity of a-chymotrypsin in RMs of bis (2-ethyl-hexyl) sodium sulfosuccinate (Aerosol-OT or AOT) in octane. Since then, many enzymes have been solubilized and studied for their activity in RMs. Other important applications of RME include tertiary oil recovery [25], extraction of metals from raw ores [26], and in drug delivery [27]. Application of RMs/mi-croemulsions/surfactant emulsions were recognized as a simple and highly effective method for enzyme immobilization for carrying out several enzymatic transformations [28-31]. Recently, Scheper and coworkers have provided a detailed account on the emulsion immobiUzed enzymes in an exhaustive review [32]. 

Sucrose acrylate derivatives can be converted into polymers and hydrogels that can be used as flocculants, water adsorbents, bioimplantables, and drug delivery devices (42). Sucrose ethers have applications as surfactants and surface coatings, and as feedstocks for synthesis of polyurethane foams and... 

Self-emulsifying drug delivery systems (SEDDS) are anhydrous solutions of the drug in oil containing surfactant and cosurfactant, which spontaneously emulsify when added to an excess of water. 

Uchegbu I, Vyas S. Non-ionic surfactant based vesicles (niosomes) in drug delivery. Int J Pharm 1998 172 33-70. 

Malmsten M. Liposomes. Chapter 4. In Malmsten M, ed. Surfactants and Polymers in Drug Delivery. New York Marcel Dekker, Inc., 2002. 

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