Biomedical subjects

G Vanlerberghe

Publications and source records attributed to G Vanlerberghe.

4 recordsLinked to original sources

PubMed1997

Polyhedral non-ionic surfactant vesicles.

Large polyhedral (2-10 microns) non-ionic surfactant vesicles (niosomes) formed from mixtures of a hexadecyl diglycerol ether (C16G2), a cholesteryl poly-24-oxyethylene ether (solulan C24) and a low level of cholesterol are being investigated as slow-release systems for ophthalmic, subcutaneous or intramuscular administration. The phase-diagram of this three-component system has been constructed and these polyhedral vesicles are found to be in the gel (L beta) phase. Confocal laser-scanning microscopy was used to confirm the complex morphology of these vesicles. The thermo-responsive nature of release of entrapped carboxyfluorescein and nicotinamide adenine dinucleotide has been studied; release is increased with increase in temperature (37 degrees C) even though the polyhedral vesicles still maintain their polyhedral shape at this temperature. The results indicate that the thermo-responsive features of the niosomes are a result of reversible changes in bi-layer permeability caused by temperature-mediated alteration in the membrane-packing characteristics of the polyethoxylated cholesterol ether.

Cholesterol↗

PubMed1990

New fatty monoesters of erythromycin A.

New fatty polyenic (linoleic, linolenic, arachidonic, linoelaidic) mono esters of erythromycin A have been synthesized by using various reagents such as acyl chloride, carboxylic acid anhydride, and mixed carbonic anhydride. These different ways of activating the fatty acid allowed a regioselectivity of esterification at position 2' of the desosamine ring or position 4" of the cladinose ring of erythromycin A. The in vitro antibacterial properties of these new esters against members of the resident flora of the human skin were determined and compared with those of erythromycin A. The number and the stereochemistry of the double bonds seem to play a crucial role in the expression of the in vitro antibacterial activity.

Bacteria↗

PubMed1985

The effect of non-ionic surfactant vesicle (niosome) entrapment on the absorption and distribution of methotrexate in mice.

Non-ionic surfactant vesicles (niosomes) prepared from a non-ionic surfactant, cholesterol and dicetyl phosphate and containing methotrexate (MTX) have been administered to mice. Given intravenously the niosomes prolong the levels of MTX in the blood, large amounts of the drug being taken up by the liver. There was also an increased uptake of MTX into the brain, perhaps due to an effect of the niosome components on the permeability of the blood brain barrier. Absorption of the drug from the gastrointestinal tract following oral ingestion, appeared to be increased at some doses; most of the entrapped MTX was taken up by the liver, but uptake of MTX into the brain was also increased. The metabolic profile of the drug is altered by the niosomes which appear to prevent the rapid formation of 7-hydroxy methotrexate.

Administration, Oral↗

PubMedDate not supplied

The effect of niosomes and polysorbate 80 on the metabolism and excretion of methotrexate in the mouse.

The effect of non-ionic surfactant vesicle (niosome) encapsulation on the metabolism and urinary and faecal excretion of methotrexate (MTX) in mice has been studied following oral and intravenous administration, and compared with the effects of co-administration of free drug and polysorbate 80, which does not form vesicles. Niosome entrapment reduces the excretion of MTX into urine and bile whereas polysorbate 80 increases its excretion. Monitoring of the levels of MTX and its 7-hydroxy metabolite indicates that entrapped MTX is protected from rapid metabolism in vivo, particularly in niosomes but to a small degree in the micellar systems formed by polysorbate.

Administration, Oral↗