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Biomedical subjects

H Fenner

Publications and source records attributed to H Fenner.

At least 37 records · Page 2Linked to original sources
PubMed1985

[The clinical pharmacokinetics of allopurinol. 2. Allopurinol/oxypurinol pharmacokinetics following allopurinol in single doses and multiple application].

In a pharmacokinetic study with 6 healthy volunteers the parameters for allopurinol and oxipurinol were compared following a single dose of allopurinol and multiple application of the drug. Pharmacokinetic data for allopurinol and oxipurinol are different after single doses and under steady state conditions. The oxipurinol half-life of 17 +/- 5.1 h is prolonged under steady state conditions to 19.7 +/- 5.8 h. Based on the results of this study and on data from different authors the range of 17-21 h is discussed as the most frequent oxipurinol half-life.

Adult↗
PubMed1982

[Transsynovial kinetics and correlation of dosage and effect of non-steroidal anti-rheumatic agents].

For NSAID's the clinical evidence of their efficacy is evaluated empirically employing tedious procedures. For diclofenac, indometacin and piroxicam proposals for a more rational procedure of their dose-response relationship determination are discussed. Preclinical data regarding the prostaglandin inhibition are correlated with pharmacokinetic parameters of target-tissue concentrations. In the range of inhibitory drug concentrations in the synovial fluid an antiinflammatory and analgesic effect can be established clinically. Studies on transsynovial kinetics of NSAID's therefore should supply appropriate evidence for an approach to their therapeutic regimen in clinical dose finding studies.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1981

[Antirheumatic therapy with new non-steroidal compounds (author's transl)].

Non-steroidal antirheumatic agents have the same type of action qualitatively: they are more or less potent inhibitors of prostaglandin synthesis and also influence other mediators of the inflammatory process. Certain risks with these substances are the inevitable side-effects of their antiinflammatory/analgesic action. Experiments to improve this type of substance have, however, produced undoubted advances in longterm treatment with antirheumatic agents: the daily therapeutic doses could be markedly reduced, the dosage scheme became simpler and consequently compliance-orientated. With demonstrably effective tissue levels at the site of the inflammation they have a sustained action on the symptoms of rheumatic diseases.

Anti-Inflammatory Agents↗
PubMed1980

[The use of allopurinol in long-term treatments for optimal effect].

The importance of allopurinol drug formulation is discussed regarding the relationship between allopurinol-oxipurinol pharmacokinetics and the mechanism of action. The oxipurinol plasma levels were simulated basing on a single dose regimen and an oxipurinol plasma half life of 14 hours. From these data it is evident, that during long term treatment of hyperuricemia and gout a sustained release allopurinol-formulation fulfills the requirement of adequately maintained oxipurinol plasma levels.

Allopurinol↗
PubMed1980

[Doxycycline pellets: a suitable formulation with guaranteed bioequivalence].

Basing on the physico-chemical properties of doxycycline relevant to an optimisation of the administration of this drug a new formulation (pellets) was developed. The bioavailability and tolerability of this formulation were studied in normal subjects in a cross-over design. The drug liberation profile of the new product excludes the risk of oesophageal irritation. The gastric tolerance of the pellet formulation is significantly better than that of the comparative product. No statistically significant differences were observed in the plasma AUC, indicating bioequivalence of the dosage forms. The values for plasma peak levels did not differ significantly, and were in agreement with the results of other studies on doxycycline bioavailability. Using the experimental data, a pharmacokinetic computer simulation of the doxycycline plasma levels for multiple-dose treatment was carried out: During the usual therapeutic dosage regimen the plasma levels are maintained above the MIC value.

Adult↗
PubMed1979

(Photo)chemistry of 5-deazaflavin. A clue to the mechanism of flavin-dependent (de)hydrogenation.

The catalytic action of 5-deazaflavin in the photochemical reduction of flavin and iron proteins [Massey, V. and Hemmerich, P. (1978) Biochemistry, 17, 9--17] is shown to be due to the highly reactive 5-deazaflavosemiquinone. This radical is generated in a complex sequence of reactions, which involves (a) covalent photoaddition of the substrate residue to the deazaflavin, (b) fast secondary photoreaction of this adduct with starting deazaflavin to yield a covalent radical dimer, accompanied by the liberation of the oxidized substrate, and (c) deazaflavin-sensitized cleavage of the radical dimer to the monomers. The structure and properties of this radical (redimerisation or dismutation) and the precursor intermediates as well as the mechanism of the photoreaction are described. Deazaflavins and their natural parent compounds are compared with respect to their different redox behavior and radical stability. The syntheses of 5-deuterated deazaflavins are described and their redox reactions are compared with those of normal deazaflavins.

Chemical Phenomena↗