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Biomedical subjects

M R Gasco

Publications and source records attributed to M R Gasco.

At least 55 records · Page 3Linked to original sources
PubMed1984

Behavior of ATP toward phenothiazine drugs.

The tricyclic amines promazine, promethazine, chlorpromazine, triflupromazine, and trifluperazine form solid ion pairs with ATP in a 1:2 molar ratio. There is a good correlation between the measured Ksp and the apparent diffusion constants of the ion pairs with the critical micelle concentration (CMC) of the corresponding phenothiazines. Solid ion pairs are solubilized by phenothiazine micelles; the binding constants of ATP to drug micelles are calculated from solubility data at 25 degrees C and can be related to the CMC of the phenothiazines.

Adenosine Triphosphate↗
PubMed1984

The influence of bile salts on the absorption in vitro and in vivo of propranolol.

The lipophilicity of propranolol is increased by some bile salts which form ion-pairs. In the presence of taurodeoxycholate, the logarithm of the apparent partition coefficient (log P) of propranolol is increased. Moreover, the apparent diffusion constants in vitro of propranolol as ion-pairs at pH 3.0-6.0 are about 5-6 times higher than those of propranolol alone. The area under the curve values of plasma concentration-time profiles of propranolol, following its oral administration to rabbits together with taurodeoxycholate, are about 1.4 times higher than those after administration of propranolol alone. Moreover, after the administration of propranolol with taurodeoxycholate the plasma concentration rises more rapidly, with a point of inflection between 0.5 and 1.5 h, than after administration of propranolol alone. Taurodeoxycholate does not modify the first-pass effect of propranolol in rabbits following intravenous and intraportal administration. The absorption of an oral dose of propranolol in the presence of taurodeoxycholate increases from 70% to 100%, due to the higher lipophilicity of the ion-pair. The plasma concentration-time curves suggest the hypothesis that greater absorption of the ion-pair occurs mainly in the upper region of the gastrointestinal tract.

Journal Article↗
PubMed1983

Binding of Phenothiazines to bovine hemoglobin.

Phenothiazines with bovine hemoglobin give solid complexes in phosphate buffer; this is due to the presence of ion-pairs between phenothiazines and phosphates. Using diluted solutions the number of sites available on each protein molecule and the intrinsic binding constants are determinated; the number of sites, in solutions and in solid complexes, is about the same for each drug, but different for the various phenothiazines.

Animals↗
PubMed1982

Behaviour of hematoporphyrin and protoporphyrin with antidepressant drugs.

Complexation between oppositely charged antidepressant drugs and porphyrin derivatives was investigated by NMR spectroscopy. The solid complexes obtained are soluble in antidepressant aggregates and a good fit was found between the values of CMC of the drugs and the values of the binding constants of porphyrins with antidepressant micelles.

Antidepressive Agents↗
PubMed1981

Determination of hematoporphyrin and protoporphyrin by ion-pair extraction with chlorpromazine.

A sensitive method based on ion-pair extraction is described for the quantification of hematoporphyrin and protoporphyrin using chlorpromazine as an ion-pair-forming agent. Extraction of the ion-pair in chloroform is obtained quickly at an optimum pH of 6.5 for hematoporphyrin and 6.5-6.8 for protoporphyrin, giving an excellent recovery of the porphyrin. A stoichiometric relationship of 1:2 between porphyrin and chlorpromazine is proved. Cyanocobalamin and liver extract do not interfere with the assay.

Chemical Phenomena↗
PubMed1979

Kinetics of dopamine oxidation by dialkylaminoalkylphenothiazine cation radicals.

The kinetics of dopamine oxidatinon dialkylaminoalkylphenothiazine cation radicals (with two- or three-carbon side chains) were investigated. The two-carbon side-chain derivatives have reaction rates higher than the three-carbon ones. For chlorpromazine and promazine, extrapolation of pH 1-6 data shows that reaction rates become very fast at physiological pH.

Chemical Phenomena↗
PubMed1978

Kinetics and mechanism of oxidation of promazine and promethazine by ferric perchlorate.

The equilibrium constants, kinetics, and mechanism of promazine and promethazine oxidation by ferric perchlorate were investigated at different temperatures and acidities using a stopped-flow spectrophotometric technique. The overall reaction can be represented as follows: (formula: see text) where P+ represents the radical cation corresponding to the phenothiazine derivative. The equilibrium quotients were evaluated at 1.00 M HClO4, 25.0 degrees, and ionic strength 1.0 M. The kinetics of reaction follow the equation: -d[P] divided by dt = k1[Fe3+][P]-k-1[Fe2+][P+] The rate constants k1 and k-1 are independent of acidity and are related to the corresponding equilibrium quotients.

Chemical Phenomena↗
PubMed1977

[Formation of an azoderivative of phenothiazine].

The reaction of phenothiazine-5-oxide in 2 N HCl with 2,4-dinitrophenylhydrazine gives rise to 3-azo-(2',4'-dinitrophenyl)phenothiazine and phenothiazine. The stoichiometric ratio is two molecules of phenothiazine-5-oxide to one molecule of 2,4-dinitrophenylhydrazine.

Azo Compounds↗