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Biomedical subjects

J H Perrin

Publications and source records attributed to J H Perrin.

At least 37 records · Page 2Linked to original sources
PubMed1988

Microcalorimetric and chromatographic investigations of the binding of some pyridine derivatives to cyclodextrins.

The binding of some pyridine derivatives to alpha-, beta- and gamma-cyclodextrins has been investigated by microcalorimetry. The strongest binding is to beta-cyclodextrin, but the binding constants are of the order 10(2) M(-1). The binding to beta-cyclodextrin was also investigated by high performance liquid chromatography. The addition of beta-cyclodextrin to the mobile phase allowed separation of molecules with similar binding constants and of racemates in the case of tropicamide.

Journal Article↗
PubMed1988

The interaction of dopexamine with various drugs and excipients in parenteral solutions.

The interaction of dopexamine hydrochloride with various excipients and other drugs in parenteral solutions has been investigated by microcalorimetry. The interaction with heparin sodium, in particular, is significant. The interaction is strongest in parenterals containing glucose and is eliminated in normal saline. Divalent cations are more effective than monovalent ones in eliminating the reaction, which is apparently ionic in nature.

Calorimetry↗
PubMed1988

Interfacial tensions and partition coefficients in water/heptane systems containing 2,6-diisopropylphenol, n-alkylphenols and cycloalkanols.

The free energies of absorption, dehydration, and transfer in a heptane-water system for a set of phenolic compounds and a series of cycloalkanols have been investigated. The free energy of adsorption depends only upon the molecular surface area of the hydrophobic fraction of the molecule, whereas the free energy of dehydration is independent of this fraction.

Chemical Phenomena↗
PubMed1988

Interaction of heparin sodium and dopamine hydrochloride in admixtures studied by microcalorimetry.

Microcalorimetry was used to investigate the interaction between dopamine hydrochloride and heparin sodium in 5% dextrose injection and in 0.9% sodium chloride injection. Heat of reaction (in microjoules) was measured by flow calorimetry for the following combinations of solutions: dopamine hydrochloride solution and heparin sodium solution prepared from powdered forms of the drugs in water; solutions of the powdered drugs in 5% dextrose injection; solutions of the powdered drugs in 0.9% sodium chloride injection; solutions prepared in 5% dextrose injection from commercial dopamine hydrochloride injection and commercial heparin sodium injection; and solutions prepared in 0.9% sodium chloride injection from the commercial drug injections. Mixing the solutions of the powdered drugs in water caused heat to be evolved, as did mixing the solutions of the powdered drugs diluted with 5% dextrose injection and the commercial injections diluted with 5% dextrose injection. The interactions of the two drugs were believed to be ionic, based on the exothermic nature of the reaction. No heat of reaction was measurable when sodium chloride was used as the diluent. Based on this preliminary investigation, admixtures containing heparin sodium and dopamine hydrochloride should be mixed in 0.9% sodium chloride injection to minimize the risk of interaction between the two drugs.

Calorimetry↗
PubMed1987

The effects of pH, calcium and chloride ions on the binding of tolmetin to human serum albumin: circular dichroic, dialysis and fluorometric measurements.

The binding of the non-steroidal anti-inflammatory drug, tolmetin (1-methyl-5-p-toluoylpyrrole-2-acetic acid) to human serum albumin (HSA) has been shown by circular dichroism, fluorescence and equilibrium dialysis to be dependent on the N-B conformational change of the albumin. The influence of calcium and chloride ions on the interaction was also investigated using the same techniques. Experiments suggested that calcium ions increased the binding constant of tolmetin to HSA whereas chloride ions decreased it. The displacement study showed that tolmetin caused a significant increase in the affinity of diazepam to HSA whereas it decreased the binding of warfarin to HSA. Tolmetin seems to cause an allosteric change in the diazepam binding site in spite of it sharing a primary site with warfarin.

Calcium↗
PubMed1986

Relative bioavailability of trimeprazine tablets investigated in man using HPLC with electrochemical detection.

The stability, partition coefficient, plasma protein binding, red blood cell distribution, and whole blood concentrations of trimeprazine were investigated. Trimeprazine solution was stable for 6 months at -20 degrees C and 3.5 months at 40 degrees C. In whole blood trimeprazine was stable for 5 weeks at -20 degrees C, 24 h at 4 degrees C, 4 h at 25 degrees C and 1 h at 37 degrees C. The apparent hexane-water partition coefficient varied from 1.50 (at pH 4.83) to over 100 (at pH 10.54). The fraction bound to plasma protein exceeded 0.9 as estimated by equilibrium dialysis with correction for volume shift. The mean plasma/red blood cell concentration ratio was 1.17 and the mean red blood cell/plasma distribution coefficient was 8.65. Six healthy adult males received single 5 mg doses of trimeprazine in a syrup (5 mg in 10 ml) and tablets with at least two weeks between doses. Blood was collected for 48 h. The mean (+/- s.e.m.) times for peak blood concentrations were 3.5 +/- 0.22 h for the syrup and 4.5 +/- 0.43 h for the tablets. There were no significant differences in Cmax values. The overall mean (+/- s.e.m.) terminal phase half-life was 4.78 +/- 0.59 h. Mean (+/- s.e.m.) areas under the concentration time curves from 0 to infinity (AUC infinity) were 11.0 +/- 1.99 ng h-1 ml-1 and 7.67 +/- 1.05 ng h-1 ml-1 for syrup and tablets, respectively. The mean relative bioavailability for the tablets was approximately 70% with respect to the syrup.

Adult↗
PubMed1985

Measurement of flurbiprofen-human serum albumin interaction by fluorimetry.

The binding of the anti-inflammatory drug, flurbiprofen, to human serum albumin is accompanied by a reduction of the fluorescence efficiency of the drug. The quenching effect has been used to evaluate the strength of binding at different pH values. Equations have also been developed for calculating binding constants for a 1:1 drug-protein complex, when fluorescence measurements are made at wavelengths where the emission spectra of the free drug, free protein and the complex overlap. Over the pH range 6.20-8.04, a binding constant of ca 1.0 x 10(7) was found for flurbiprofen.

Journal Article↗
PubMed1984

Absorption and disposition of ethambutol in rabbits.

The absorption and disposition of ethambutol was examined in six rabbits in a three-way crossover study. Each rabbit received 45-mg/kg doses of ethambutol in three treatments: one intravenous injections and two oral solutions, ethambutol alone and ethambutol in the presence of aluminum hydroxide (40 mg/kg). Half-lives of ethambutol ranged from 2.26 to 5.20 h when administered alone and 2.18 to 4.00 h when coadministered with the antacid; the difference was not significant (p greater than 0.3). Mean clearance after the oral administrations (189.2 mL/min/kg) was significantly greater than the mean intravenous clearance (43.7 mL/min/kg) (p less than 0.01), suggesting a first-pass metabolism of ethambutol when administered nonparenterally to rabbits. The volume of distribution ranged from 5.5 to 17.8 L/kg, suggesting an extensive distribution of ethambutol outside the central compartment and, possibly, a localized deposit within the body tissues. Mean bioavailability of ethambutol was approximately 28% and was not affected by the presence of aluminum hydroxide. The rate of ethambutol absorption, however, was slightly delayed by the antacid.

Aluminum Hydroxide↗
PubMed1984

Plasma nitroglycerin concentrations and hemodynamic effects of sublingual, ointment, and controlled-release forms of nitroglycerin.

After a sublingual test dose, 12 healthy men aged 21 to 29 yr were treated with controlled-release transdermal nitroglycerin skin patches designed to deliver 10 mg/day nitroglycerin and with nitroglycerin ointment (2%) (1-in amount from the tube spread over 50 cm2) for 24 hr in a double-blind crossover study. Assessment was by measurement of nitroglycerin in plasma, blood pressure, and pulse rate. The mean plasma concentration of nitroglycerin during ointment dosing was approximately 200% to 400% that during skin patch dosing. Levels during ointment dosing were closer to those from sublingual dosing than were those during skin patch dosing. Blood pressure and pulse rate changes were much the same during both transdermal treatments. Calculations showed that delivery of nitroglycerin from the skin patches would have to be over 40 to 80 cm2 of the skin to achieve nitroglycerin exposure of the order of that induced by 1 in of ointment spread over 50 cm2 or from sublingual dosing.

Administration, Oral↗
PubMed1983

Acetaminophen-aluminum hydroxide interaction in rabbits.

Acetaminophen-aluminum hydroxide interaction was investigated in a crossover study using six rabbits. Blood samples were collected at various time intervals for up to 6 hr following the oral administration of acetaminophen alone or in combination with aluminum hydroxide. Aluminum hydroxide at a 40-mg/kg dose did not appear to affect the rate and extent of acetaminophen absorption. The influence of aluminum hydroxide on gastric emptying could be compromised by gastric absorption of acetaminophen, resulting in a negligible effect on the overall bioavailability of acetaminophen.

Acetaminophen↗
PubMed1982

Liquid chromatographic assay of phenothiazine, thioxanthene and butyrophenone neuroleptics and antihistamines in blood and plasma with conventional and radial compression columns and UV and electrochemical detection.

An assay strategy for determining a wide range of phenothiazine, thioxanthene and butyrophenone neuroleptics and antihistamines both alone and in combination in blood and plasma is described. The general method employs liquid chromatography with both conventional and radial compression nitrile bonded columns. Detection is by ultraviolet absorption spectrophotometry or by amperometry depending on the concentrations to be measured. Ultraviolet absorption is suitable down to 10 ng/ml. Below this level amperometry is preferable. The various compounds are used as internal standards for each other. The lower limit of detection is approximately 0.1 ng ml-1 with 10-ml sample. The with-run coefficient of variation is a maximum of 7.3%.

Antipsychotic Agents↗
PubMed1981

Circular dichroic examination of the interaction of some planar acidic drugs with tryptophan-modified human serum albumin.

The single tryptophan region in human serum albumin was investigated for its involvement in binding planar hydrophobic and acidic drug molecules. The lone tryptophan was alkylated with a selective and specific agent, 2-hydroxy-5 nitrobenzyl bromide. The subsequent interaction of four drug molecules with tryptophan modified, and normal albumin was examined by circular dichroism (CD). In all cases the CD signal of tryptophan modified albumin was perturbed at low drug concentrations. The predominantly alpha-helical structure of the albumin remained intact. It is suggested that the primary binding site of these four acidic planar drugs does involve the tryptophan region.

Acids↗