Minor alkaloids of tobacco release [3H]dopamine from superfused rat striatal slices

In addition to S(-)-nicotine, several minor tobacco alkaloids ((+/-)-nornicotine, anabaseine, S(-)-anabasine, and S(-)-N-methylanabasine) are present in tobacco smoke. This study demonstrates that these alkaloids increase fractional 3H release in a concentration-dependent manner from rat striatal slices preloaded with [3H]dopamine, with desensitization of this response. The rank order of EC50 values was S(-)-nicotine (3.0 +/- 2.2 microM) > (+/-)-nornicotine (6.7 +/- 2.1 microM) > anabaseine (15.4 +/- 6.1 microM) = S(-)-N-methylanabasine (16.3 +/- 4.7 microM) = S(-)-anabasine (19.3 +/- 3.2 microM). The alkaloids did not modulate fractional 3H release evoked by electrical-field depolarization. Thus, minor tobacco alkaloids may contribute to the apparent neuroprotective effects of smoking in neurodegenerative diseases.

Application of dual radiotelemetric technique in studying drug-drug interaction between diclofenac sodium and ranitidine HCl in volunteers

Drug-drug interaction between a commercial diclofenac sodium enteric-coated tablet (Voltaren; V) and a ranitidine HCl tablet (Zantac; Z) was evaluated using a dual radiotelemetric technique according to a randomized three-way Latin-Square crossover design balanced for carryover effects. V and Z were given either alone or in combination (Treatment V, Z, V/Z), with a 14-day washout period between treatments. Eighteen fasted subjects swallowed a tethered. Heidelberg pH capsule to provide continuous gastric pH. Then the assigned treatment drug and another Heidelberg pH capsule were given simultaneously. The free pH capsule provided information regarding gastric residence time (GRT). Serial blood samples were obtained for up to 12 hr after dosing and drug levels were determined by validated HPLC methods. Treatment effects on AUC, Cmax, Tmax, Tlag, Tmax-Tlag, and T1/2 were not significant except Cmax, which differed slightly for both V and Z when given in combination as compared to alone. Gastric residence times were 46, 33, and 51 min for Treatments V, Z, and V/Z, respectively. Gastric exposure of the enteric-coated tablet of diclofenac was estimated by pH values obtained from the tethered capsule. Median pH values at 3 and 15 min prior to gastric emptying were 3.8 and 4.9 for the combination treatment versus 2.1 and 2.7 for diclofenac alone. The results of this study indicated that there was minimal drug-drug interaction between diclofenac and ranitidine. The gastric pH range resulting from this study did not influence the oral absorption of enteric-coated diclofenac.

[Efficacy of xiaoxingzhang guttae ophthalmic eye drops in the treatment of experimental herpes simplex keratitis]

The new guttae ophthalmic Xiaoxingzhang (XXZ) was extracted from Radix Actinidiae, a traditional Chinese herbal drug. The 50% inhibition concentration (IC50) of XXZ on type I Herpes Simplex Virus (HSV-1) in virus cell cultures is 165.48-174.73 micrograms/ml. However, XXZ concentrations greater than 400 micrograms/ml did not cause any microscopically visible disruption of vero cells. The efficacy of XXZ in the treatment of experimental Herpes Simplex Keratitis (HSK) in rabbits is higher than that of idoxuridine. The effective doses of XXZ are not toxic to corneal epithelium. The results suggest that XXZ as a new anti-HSV preparation is potentialy useful in the treatment of patients with HSK.

Two-dimensional spectroscopy of electrophoretic gels

Optical techniques are described which permit one to analyze two-dimensional electrophoretic gels in a fashion which is analogous to the one-dimensional spectroscopy of solutions. In the methods described, an electrophoretic gel is irradiated with monochromatic light and isozyme patterns are detected by the absorption of light or the fluorescent emission of light. The system described can both generate and detect monochromatic light in a range from 200 to 1100 nm. Without the use of histochemical stains, several isozymes have been visualized by purely optical means. Five methods for the visualization of lactate dehydrogenase and five methods for the demonstration of trypsin isozymes are described. In addition, general methods have been formulated for hydrolases and oxidases. Gel spectroscopy should permit the investigation of a wide range of new isozymes.

Excretion and biotransformation of carboxymethyl-cysteine in rat, dog, monkey and man

1. Following an oral dose of S-carboxymethyl [35S]cysteine monkey (rhesus and African green), rat, dog, and man excreted 77,88,95, and 100% respectively of the 35S radioactivity in urine and 7.0, 2.5, 0.7, and 0.3% in faeces during a 3 to 4 day period. 2. The principal drug-related components excreted were unchanged carboxymethylcysteine, dicarboxymethyl sulphide and inorganic sulphate. 3. Rat, dog, and man excreted primarily dicarboxymethyl sulphide and unchanged carboxymethylcysteine and no inorganic sulphate (rat, 7%). 4. Monkey excreted largely inorganic sulphate, moderate amounts of dicarboxymethyl sulphide and a trace of unchanged drug.

Metoclopramide metabolism and determination by high-pressure liquid chromatography

A high-pressure liquid chromatographic method suitable for determining plasma metoclopramide levels at normal (10-20 mg) doses is described. Eight metabolites as well as metclopramide were isolated and identified in rat, dog. and human urine. The only common metabolite in these species is 2-[(4-amino-5-chloro-2-methoxybenzoyl)-amino] acetic acid. N-Deethylation is a major pathway for metoclopramide metabolism in the lower animals but not in humans. Metoclopramide is excreted mainly unchanged or as its conjugates by humans.

Disposition and metabolism of 3-(3-chlorophenoxy)-N-methylpyrrolidine [14C]-carboxamide in the rat, dog, and man

Studies with a 14C-labeled sample have shown that the title compound A is readily absorbed and very rapidly excreted by the rat, dog, and man. The metabolites result from aromatic ring hydroxylation, oxidation, and dealkylation of the urea methyl group, and oxidative ring opening of the pyrrolidine ring. Rat metabolites were 3-(3-chloro-4-hydroxyphenoxy)-N-methyl-l-pyrrolidinecarboxamide (C) 3-(3-chloro-4-hydroxyphenoxy)-1-pyrrolidinecarboxamide (D), 3-(3-chlorohydroxyphenoxy)-1-pyrrolidinecarboxamide (E), 3-(3-chlorophenoxy)-4([(methylamino)-carbonyl]amino)butanoic acid (G), 3-(3-chlorophenoxy)-4[(aminocarbonyl)amino]butanoic acid (H). Dog metabolites were C, D, G, and H. Human metabolites were 3-(3-chloro-4-hydroxyphenoxy)-N-formyl-l-pyrrolidinecarboxamide (F), C, D, G, and H. An electron-capture gas chromatographic assay for the parent compound is described. Whole-body autoradiograms of rat slices and the tissue residue data from these slices are reported and indicate rapid tissue depletion of radioactivity.

Disposition of bethanidine, N-benzyl-N',N''-dimethylguanidine, in the rat, dog and man

Bethanidine is metabolized in the rat and dog to a significant degree to N-benzyl-N'-methylguanidine, N-benzylguanidine, N-hydroxybenzyl-N'-methylguanidine, N-methylguanidine, N-hydroxybenzyl-N',N''-di-methylguanidine, and benzoic acid, whereas in man the drug is not metabolized. It is readily absorbed in all three species. The elimination kinetics in man show a difference between the urinary excretion rate and the rate of decline in the blood. Whole body autoradiograms showed a high concentration of drug in rat tissues rich in adrenergic nerve terminals, but insignificant penetration, if any, of the blood-brain barrier.

The Rate of Recombination of H Atoms in the Presence of NH3

The rate constant for the homogeneous recombination of H atoms in the presence of NH3, with He as carrier gas, has been determined at 298°K in a fast flow system, over the pressure range 1.50 to 4.55 Torr, using e.s.r. technique. A value of either 4.00 × 1016 or 5.14 × 1016 cm6 mol−2 s−1 was calculated, depending upon the rate constant taken, or estimated, from the literature for the recombination in the presence of helium.