Biomedical subjects

R Fickat

Publications and source records attributed to R Fickat.

3 recordsLinked to original sources

PubMed1990

Studies on the activity of bepridil as a scavenger of free radicals.

Bepridil, a calcium antagonist with anti-anginal, anti-ischemic, and anti-arrhythmic properties was assessed for its ability to scavenge free radicals. Bepridil reduced the stable free radical 1,1-diphenyl-2-picrylhydrazil (DPPH) in the molar ratio 2:1 and, in this respect, was as active as the reference anti-oxidants hydroquinone and alpha-tocopherol. Allopurinol and SOD inhibited cytochrome c reduction in a hypoxanthine-xanthine oxidase superoxide generating system, whereas bepridil was ineffective. Deoxyribose degradation induced by the .OH radical was prevented by bepridil (IC50 = 0.050 mM). This ability to scavenge .OH was similar to that of dimethyl sulfoxide (DMSO) (IC50 = 0.056 mM) and more potent than that observed with mannitol and allopurinol (IC50 values of 0.74 mM and 0.92 mM, respectively). The powerful .OH scavenging activity of bepridil was confirmed in vivo on alloxan induced diabetes in mice. Bepridil exerted a marked protective effect at 0.150 mmol/kg whilst, ethanol and DMSO were active at the doses of 90 and 94 mmol/kg, respectively. These results demonstrate that bepridil is a potent .OH radical scavenger. This property may contribute to the therapeutic activity of this drug in myocardial ischaemia.

Allopurinol↗

PubMedDate not supplied

Biodegradable cross-linked albumin microcapsules for embolization.

The interfacial polymerization process used in the present study produced individual cross-linked albumin microcapsules, the particle size of which depended on the emulsification stirring rate. The variation in cross-linking agent concentration altered the microcapsule wall properties. As shown by SEM observations, microcapsules prepared with low acyl chloride concentrations presented rippled surfaces, while the surfaces of the microcapsules prepared with high acyl chloride concentrations were smooth. It was then suggested that the membranes of the weakly cross-linked microcapsules consisted of cross-linked and denatured albumin. Embolization experiments in the dog kidney showed that the weakly cross-linked microcapsules were biodegradable within 7 days, whereas the highly cross-linked microcapsules were degraded over more than 14 days and led to prolonged ischaemia. The results of the histological experiments carried out on a further eight dogs supported the previous findings yielded by the angiographical experiments. Moreover, they indicated that no foreign body reaction occurred. The lack of this inflammatory granuloma should be attributed to the rapid biodegradation of the microcapsules which produced reversible ischaemic lesions.

Animals↗

PubMedDate not supplied

Ion-exchange albumin microcapsules of doxorubicin: an in vitro release kinetic evaluation.

Cross-linked albumin microcapsules were prepared, using a polycondensation interfacial process. Doxorubicin was incorporated in these microcapsules by simple adsorption from aqueous solution. Increasing the extent of cross-linkage of the microcapsule walls by either increasing the cross-linking agent concentration or the time of reaction significantly reduced the absorption ability of these microcapsules. Doxorubicin release kinetic evaluation revealed that the presence of a salt in the release medium was needed to enable much of the drug to be released. Furthermore, the doxorubicin displacement intensity from the microcapsules was dependent on the nature and concentration of the cations used, indicating that an ion-exchange process was involved. Analysis of the various doxorubicin release profiles, using ion-exchange kinetic equation, showed that the release kinetic process is governed by a film diffusion process at low and moderate Na+ ion concentrations in the exchanging solution, and by a particle diffusion process at high Na+ ion concentrations, sufficient to drive the doxorubicin exchange to completion.

Capsules↗