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Biomedical subjects

C Thies

Publications and source records attributed to C Thies.

32 records · Page 2Linked to original sources
PubMed1982

Microcapsules as drug delivery devices.

This review will deal with techniques for producing drug-filled microcapsules, current applications of such microcapsules, and projected applications of microcapsules as drug delivery devices. Specific encapsulation techniques to be evaluated include coacervation, solvent evaporation, interfacial polymerization, emulsion, and hot melt processes. Selection of capsule coating materials will be another factor considered. Differences in specific design requirements of capsules to be administered i.v., i.m. (or s.c./i.p.), and orally will be discussed at length. Specific examples of current capsules administered by each of the routes will be given.

Animals↗
PubMed1981

Trauma as an etiologic and aggravating factor in multiple sclerosis.

We carried out a retrospective and prospective epidemiologic study designed to detect an association between trauma and multiple sclerosis in 130 patients and 82 age- and sex-matched controls. Electrical injury was followed by an increased frequency of exacerbation, which did not achieve statistical significance. There was no statistically significant association between other types of trauma and onset or deterioration of the disease. These findings do not prove that such an association cannot exist for any one individual patient; however, they do not provide evidence to support this idea.

Electric Injuries↗
PubMed1976

In vivo and in vitro evaluation of a microencapsulated narcotic antagonist.

Injectable microcapsules containing 75% (w/w) cyclazocine, a narcotic antagonist, were prepared with dl-poly(lactic acid) as the coating material. Capsule fractions falling between 105 and 295 mum released about 90% of their cyclazocine in 8 days of rotating-bottle extraction at 37 degrees in pH 7.4 phosphate buffer. Although larger capsules released the drug somewhat more slowly, all capsules released cyclazocine far more rapidly than an ideal capsule should. This rapid release is attributed to macroscopic defects located in the capsule walls. The ability of the capsules to block the action of morphine in vivo was assessed by injection of a sesame seed oil suspension into Holtzman rats. A hot-plate test procedure was used to evaluate animal behavior. Capsule doses of 100-250 mg/kg to rats caused significant antagonism of morphine's analgesic effect for 14 days after injection. By Day 17, no antagonism occurred, indicating that the capsules completely released the drug in vivo between 14 and 17 days after injection.

Animals↗
PubMed1976

Development of injectable microcapsules for use in the treatment of narcotic addiction.

Injectible microcapsules containing narcotic antagonists have been prepared with dl-poly (lactic acid) as the coating material. The encapsulation technology has developed to the point that high yields of less than 180 mu capsules can be prepared routinely. Such capsules with an initial payload of 50 wt. % naltrexone pamoate provide 60-90% antagonism to the action of morphine 28 days after injection into mice as a peanut oil/aluminum monostearate suspension at a dose level of 40 miligrams naltrexone pamoate/ kg. mouse.

Animals↗
PubMed1975

Development of injectable microcapsules for use in the treatment of narcotic addiction.

Injectible microcapsules containing narcotic antagonists have been prepared with dl-poly (lactic acid) as the coating material. The encapsulation technology has been developed to the point that high yields of less than 180 mu capsules can be prepared routinely. Such capsules with an initial payload of 50 wt. per cent naltrexone pamoate provide 60-90 per cent antagonism to the action of morphine 28 days after injection into mice as a peanut oil/aluminum monostearate suspension at a dose level of 40 miligrams naltrexone pamoate/kg. mouse.

Animals↗
PubMedDate not supplied

A supercritical fluid-based coating technology. 3: preparation and characterization of bovine serum albumin particles coated with lipids.

Solvent-free microparticles, loaded with bovine serum albumin as a model protein, were produced using a novel supercritical (SC) fluid-based coating technology. Coating material consists either of trimyristin (Dynasan 114) or of Gelucire 50-02. Microparticles obtained were characterized as regards their morphology, protein content and in vitro release profile. A discontinuous coating made of micro-needles of trimyristin led to an initial burst release of approximately 70% in 30 min. However, a prolonged release of the BSA could be achieved in a phosphate buffer solution at 37 degrees C over a 24 h period from particles coated with Gelucire 50-02. Furthermore, it was shown that BSA does not undergo any degradation after SC CO(2) treatment under the conditions used in the coating process.

Capsules↗
PubMedDate not supplied

A supercritical fluid-based coating technology. 2: solubility considerations.

Solubility measurements of candidate coating materials have been performed in supercritical (SC) CO(2) so as to select appropriate coating materials for implementation of a solvent-free coating process previously described. Solubility of lipidic compounds such as waxes (paraffin, beeswax, Carnauba wax), pure triglycerides (tricaprin, trimyristin, tripalmitin, tristearin) and mixture of glycerides and fatty acid esters (Gelucire) in SC CO(2) were evaluated in a static mode under different temperature and pressure conditions, ranging from 13-52 degrees C and from 50-220 bar, whether the CO(2)was in its liquid or SC state. It was shown that the compounds which are mixtures of various components give rise to a selective extraction of the lower melting point components, as evidenced from thermal analysis of soluble and insoluble fractions of the coating materials.

Capsules↗
PubMedDate not supplied

A supercritical fluid-based coating technology 1: process considerations.

A novel solvent-free particle coating process, based on the solvent properties of supercritical fluids (SCF) is described. It consists of dissolving one or more coating materials in supercritical CO(2) and then adjusting T/P conditions in the autoclave so that the coating material becomes insoluble in the CO(2). This insolubilization step causes a coating to deposit on the surface of suspended particles. This process has been applied to bovine serum albumin and sugar granules. Coating was effective, but different morphologies were obtained depending on the coating material used. A discontinuous coating has been made using trimyristin, since this material precipitates as micro-needles. Conversely, a smooth, regular coating has been obtained with a commercially available mixture of glycerides and glyceride esters of PEG (Gelucire 50/02) acting like a film-forming agent.

Capsules↗