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Biomedical subjects

H G Weder

Publications and source records attributed to H G Weder.

27 records · Page 2Linked to original sources
PubMed1975

[Studies on the binding of some parasympatholytics to bovine serum albumin/measurement of relaxation times (author's transl)].

The interactions of the parasympatholytic drugs adiphenin, adiphenin H and propantheline and the structurally related compounds diphenhydramine, D-propoxyphene and methadone with bovine serum albumin (BSA) are studied by means of 1H-NMR-spectroscopy. The relaxation rates of essential protons or proton groups of the bound ligands are obtained by a plot of the observed relaxation rates, which are determined from the alterations of the line widths in the presence of BSA, versus the biopolymer concentration. From the stabilization factors R thus obtained it can be concluded that there exist defined but relatively weak associations between these drugs and BSA; both the hydrophobic aryl moieties and the ionized amino groups are involved in these interactions.

Dextropropoxyphene↗
PubMedDate not supplied

Fate of different kinds of liposomes containing dexamethasone palmitate after intra-articular injection into rabbit joints.

The fate of oligolamellar and multilamellar vesicles containing dexamethasone palmitate after intra-articular injection into healthy rabbit joints was investigated to improve the liposome formulation in respect to better bioavailability of the effective substance within the arthritic joint. The defined negatively charged oligolamellar vesicles (dexamethasone) palmitate, egg phosphatidylcholine, phosphatidic acid, molar ratio 0.24:10.1) of a mean diameter of 0.75 micron gave better results than multilamellar vesicles (dexamethasone palmitate, dipalmitoylphosphatidylcholine, phosphatidic acid, molar ratio 0.24:10:1) used for the same purpose by several other authors. The positive charge carrier stearylamine does not induce any improvement.

Animals↗
PubMedDate not supplied

Pharmacokinetics of small unilamellar liposomes and incorporated lonazolac after i.m. administration.

The nonsteroidal anti-inflammatory drug lonazolac [3-(p-chlorophenyl)-1-phenylpyrazole-4]-acetic acid was incorporated into the bilayer of liposomes. The unilamellar and homogeneously sized liposomes with a diameter of 45 +/- 7 nm were prepared by controlled detergent dialysis. The maximal amount of lonazolac incorporation is 0.140 mg per mg egg phosphatidylcholine (egg PC). The liposomes were stable over a year. Pharmacokinetics of the 3H- and 14C-labelled liposomes and of the 14C-labelled lonazolac was investigated after i.v. and i.m. administration to rabbits. The i.m. injected liposomes showed a terminal half-life of 74 h and after 24 h 7 per cent of the administered lecithin was still in the plasma. Eight hours following the i.m. injection of the liposomes, the plasma levels of lonazolac were significantly higher compared to the reference. A portion of the liposomes was released from the muscle into the circulation. A great share of lonazolac was quickly interchanged between the liposomes and the surrounding tissue. In additional experiments small oligolamellar liposomes should be used to decrease the interchange of lonazolac and to enhance the plasma levels of liposomal incorporated lonazolac.

Animals↗
PubMedDate not supplied

The use of liposomes for the preparation of protein-free lipid emulsions models of chylomicron remnants.

Artificial chylomicron remnants were investigated as a new drug carrier system for the targeting of hepatic parenchymal cells. The emulsions presented here are similar in particle size and composition to natural lipoproteins. The preparations contained triolein, phospholipid, cholesterol and cholesteryl oleate. Egg yolk lecithin was either used to form multilamellar or unilamellar liposomes or it was incorporated into a lipid film prior to emulsification. Typically the lipid film contained triolein, cholesterol and cholesteryl oleate. When multilamellar liposomes were used however, cholesterol and cholesteryl oleate were incorporated into the vesicles. The emulsions were prepared by ultrasonication or by means of a microemulsifier. The unilamellar liposomes used with the microemulsifier yielded the best particle distribution, i.e. in the range of 40-60 as determined by quasi-elastic light scattering. The advantage of the method results from the complete emulsification of the components. The particle size remained unchanged during storage, although flocculation was observed. The results show that the synthesis of artificial chylomicron remnants in a microemulsifier is possible and reproducible.

Cholesterol↗