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Biomedical subjects

W Schatton

Publications and source records attributed to W Schatton.

10 recordsLinked to original sources
PubMed1989

Influences of tromantadine and nonoxinol 9 on the stability of red cell membrane.

The antiviral compound tromantadine (ViruMerz) and the detergent nonoxinol 9 have been investigated in their effects on biophysical parameters of red cell membranes. Up to a maximum ratio of 1 mol per 800 mol of phospholipids tromantadine enhances the membrane phase transition/separation break at 16-20 degrees C measured by 1-anilinonaphthalene-sulfonate (ANS) fluorescence. It also increases order parameters obtained from spin labeling experiments with 5-doxyl stearic acid. Nonoxinol 9 interacts with the membrane at a maximum ratio of 1 mol per 40 mol of phospholipids determined by UV spectrophotometry. The substance decreases the intensity of the above phase transition/separation break and the order parameters of the spin label 5-doxyl stearic acid. These experiments indicate that tromantadine probably stabilizes the membrane whereas nonoxynol 9 exhibits opposite effects. Combination of both compounds equalizes the influences of the single substances on the above biophysical parameters of red cell membrane with predominance of the nonoxinol 9 effect.

Amantadine↗
PubMed1988

Interaction of memantine with cholecystokinin receptors in mouse brain.

The effect of memantine on CCK receptors in mouse brain has been investigated using particles of dissected cortex and striatum. Total binding of radio-labelled CCK33 was one-half maximal within 10 min of incubation and reached a maximum after 30 to 60 min when either cortex or striatum was used. Non-specific binding (presence of 100 microM unlabelled CCK8) was 50 to 80% of total binding at steady state conditions. CCK8 inhibited specific binding of radiolabelled CCK33 in a dose-dependent manner; the IC50 (half-maximal inhibitory concentration) was in the range 3 to 4 nM. Memantine increased CCK binding in a concentration-dependent manner, though at high concentrations. The EC50 (half-maximal effective concentration) of this effect was less than 100 microM. The memantine effect is not due to an inhibition of labelled CCK degradation in the medium. The effect of memantine on CCK binding is unique for brain since it was not observed in pancreatic acinar membranes. These data, therefore, suggest a modulatory effect of memantine on CCK receptors in mouse brain (cortex and striatum) particles.

Amantadine↗
PubMed1987

Radioelectroencephalographic comparison of memantine with receptor-specific drugs acting on dopaminergic transmission in freely moving rats.

Chronic implantation of four bipolar concentric electrodes into frontal cortex, hippocampus, striatum and reticular formation allows repetitive recordings of field potentials from freely moving rats. After radiotransmission the EEG signals are submitted to a quantitative spectral power analysis. Drug-induced changes in single frequency bands as obtained from the power spectra from different brain areas lead to a drug-specific pattern which can be compared with those of various standard compounds known to influence dopaminergic transmission in the central nervous system. With regard to receptor specificity the research compounds SK & F 38393 (D-1 agonist), SCH 23390 (D-1 antagonist), quinpirole (D-2 agonist) as well as haloperidol (D-2 antagonist, less specific) are tested under identical conditions. Memantine (1-6 mg/kg, i.p.) induces power decreases in a dose-dependent manner in nearly all frequency bands thus resembling the action of apomorphine. Less similar but still comparable is the action of amphetamine, whereas among the receptor-specific dopaminergic drugs only SK & F 38393 can be regarded as similar in as much as mainly delta, alpha-2 and beta-1 frequencies decrease at the same time. Thus memantine develops its own specific pattern of changes in the EEG which can be used to discriminate it from other drugs. The results are in accordance with the drug's proposed action of enhancing the dopaminergic transmission, which probably implies an indirect mechanism of action as biochemically no direct interaction with any of the dopaminergic receptors has been described for memantine so far.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1985

Bioavailability studies of etofibrate in rhesus monkeys.

Etofibrate (Lipo-Merz) is a newer antilipaemic agent that contains the nicotinic and clofibric acid moieties joined together through a diester link with ethylene glycol. The bioavailability of these moieties in etofibrate was compared to that from equimolar amounts of these drugs administered alone to rhesus monkeys (clofibric acid 354 mg, nicotinic acid 203 mg). For this comparative purpose, analytical methods were chosen which converted etofibrate and its initial metabolites into clofibric and nicotinic acid. Following this treatment, the rate and extent of bioavailability of unchanged nicotinic acid from etofibrate was significantly lower (P less than 0.01) than that from nicotinic acid alone. Mean peak whole blood levels of 11.9 micrograms/ml at 2.8 h and 35.3 micrograms/ml at 1.3 h, respectively, occurred after administration of etofibrate and nicotinic acid alone. The extent of bioavailability of clofibric acid hydrolysed from etofibrate was not significantly different (P greater than 0.05) from that from clofibric acid alone. However, mean peak plasma levels of 127.3 micrograms/ml at 3.6 h and 170.8 micrograms/ml at 2.4 h, respectively, occurred after administration of etofibrate and clofibric acid alone and were significantly different (P less than 0.01). The rates and extent of bioavailability of nicotinic acid or clofibric acid administered as a mixture were similar to that from these drugs administered alone. Thus either drug did not affect the absorption of the other in rhesus monkeys. The half-lives of nicotinic acid (in whole blood) and clofibric acid (in plasma) in rhesus monkeys when these drugs were administered alone were 9.9 h and 1.8 h, respectively.

Animals↗
PubMed1984

Relative bioavailability of etofibrate. A comparison of an acute and a new sustained release formulation.

The relative bioavailability of 2-(p-chlorophenoxy)-2-methylpropionic acid [2-(nicotinyloxy)-ethyl]-ester (etofibrate) from Lipo-Merz retard (500 mg) with respect to Lipo-Merz (600 mg) has been determined in 10 health volunteers in a crossover study. Etofibrate was determined in plasma after hydrolysis to clofibrinic acid. Pharmacokinetic parameters were derived to describe the plasma concentration-time profiles using a minimisation of least squares technique. The absorption was apparently delayed following the sustained release formulation with a longer time to maximum plasma concentration, which was significantly lower following the retard form. No significant differences were found in the mean apparent elimination half-lives nor areas under the plasma concentration-time curves indicating that the two formulations can be considered bioequivalent.

Adult↗
PubMed1983

[Atherosclerosis treatment with etofibrate retard. New perspectives].

In a multicentric general-practice-study 2504 hyperlipoproteinemic patients were treated with etofibrate retard for 4 weeks. The drug was administered once daily in the evening. A highly significant decrease of the mean values of cholesterol around 18.4% and 27.6% resp., and of the mean triglycerides between 31.3% and 16.5% resp. were observed. The atherogenic index was reduced by 28%. The simultaneous, highly significant reduction of blood glucose and of uric acid levels as well as of blood pressure showed the comprising effects of etofibrate retard against the atherosclerosis and its risk factors. The excellent tolerance of the drug was stated by more than 99% of the patients treated.

Arteriosclerosis↗
PubMed1977

[On a novel Fomocaine synthesis/10th communication: on syntheses of new compounds with local anaesthetic activity (author's transl)].

4-[3-(4-phenoxymethyl-phenyl)-propyl]-morpholine (fomocaine, Erbocain) is a very active topical local anaesthetic with low toxicity. A new synthesis starting from 4-phenoxy-methyl-benzonitrile, via a modified Willgerodt-Kindler reaction, is reported. The yield is of the same order as with the known technical process starting from 3-phenylpropanol. The distinct advantage of the new procedure is the avoidance of the C-chloromethylation of 3-phenylpropylchloride during which process the o-chloromethyl derivative is also formed, and this cannot be separated by fractional distillation.

Chemical Phenomena↗