References: Lecithin
J Parenter Sci Technol. 1992 Sep-Oct;46(5):150-5.
A novel method of determination of protein stability.
Burgess DJ, Yoon JK, Sahin NO.
Department of Pharmaceutics, University of Illinois, Chicago 60612.
A novel method of determination of protein stability is described, which involves interfacial shear rheology of adsorbed protein layers. This technique provides information on the structural-mechanical properties of the adsorbed protein layers which can be related to: the rate of interfacial adsorption, interfacial interactions, and conformational changes in the adsorbed layers. The interfacial shear rheology of the blood proteins, bovine serum albumin and human immunoglobulin G was investigated. The air/aqueous and oil/aqueous interfaces were studied and the interfacial rheological activity of BSA was shown to be similar at three hydrophobic interfaces: air, squalene and mineral oil. The kinetics of interfacial film formation was shown to be time dependent, and aging effects were detected in both interfacial and bulk molecules. The absolute interfacial elasticity values decreased as the temperature increased. The protein solutions exhibited no interfacial rheological activity in the presence of the small surfactant molecules, Tween 80 and lecithin, under the conditions studied.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1432452&dopt=Abstract lecithin
J Pharm Sci. 1992 Sep;81(9):871-4.
Lecithin organogel as matrix for transdermal transport of drugs.
Willimann H, Walde P, Luisi PL, Gazzaniga A, Stroppolo F.
ETH-Zentrum, Institut fur Polymere, Zurich, Switzerland.
Organogels obtained by adding small amounts of water to a solution of lecithin in organic solvents were studied as matrices for the transdermal transport of drugs. Gels obtained from isopropyl palmitate and cyclooctane were used (molar ratios of water to lecithin of 3 and 12, respectively). Preliminarily histological studies showed that the gels have no harmful effect when applied to the skin for prolonged periods. Data relative to the stability of the organogels with time are also presented. Scopolamine and broxaterol were used as model drugs, and the transdermal experiments were done with a Franz diffusion cell and human skin obtained from plastic surgery. The transport rate of scopolamine obtained with the lecithin gels was about one order of magnitude higher than that obtained with an aqueous solution of the drug at the same concentration. In contrast, the transport rates of scopolamine obtained with the microemulsion solution prior to gelation (molar ratio of water to lecithin, 0) were not different from those obtained with the gel. The same variations in transport rates were observed for broxaterol, in which case the flux through the skin was directly proportional to the concentration of drug in the gel. At a concentration of broxaterol of 75 mg/mL in the donor gel, the flux was 47 micrograms.h-1.cm-2. Because preliminary results showed that transdermal transport is successful with amino acids and peptides also, it is concluded that lecithin gels may be efficient vehicles for the transdermal transport of various drugs.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1432631&dopt=Abstract lecithin
J Toxicol Environ Health. 1992 Nov;37(3):391-409.
Contrasting respirable quartz and kaolin retention of lecithin surfactant and expression of membranolytic activity following phospholipase A2 digestion.
Wallace WE, Keane MJ, Mike PS, Hill CA, Vallyathan V, Regad ED.
National Institute for Occupational Safety and Health, Division of Respiratory Disease Studies, Morgantown, West Virginia.
Respirable-sized quartz, a well-established fibrogenic mineral dust, is compared with kaolin in erythrocyte hemolysis assays after treatment with saline dispersion of dipalmitoyl phosphatidylcholine, a primary phospholipid component of pulmonary surfactant. Both dusts are rendered inactive after treatment, but the membranolytic activity is partly to fully restored after treatment with phospholipase A2, an enzyme normally associated with cellular plasma membranes and lysosomes. Phospholipid-coated dusts were incubated for periods of 2-72 h at a series of applied enzyme concentrations, and the adsorbed lipid species and hemolytic activity were quantitated at each time for both dusts. Surfactant was lost more readily from quartz than from kaolin, with consequent more rapid restoration of mineral surface hemolytic activity for quartz. Interactions of surfactant and mineral surface functional groups responsible for the mineral-specific rate differences, and implications for determining the mineral surface bioavailability of silica and silicate dusts, are discussed.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1433378&dopt=Abstract lecithin
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