Effects of cold stress and ether stress on aminopyrine demethylation kinetics in vivo

The effect of cold stress and ether stress on mixed function oxidase activity in vivo has been studied using the aminopyrine-^?14CO₂ exhalation rate (CER) method. Cold stress following both acute and chronic exposure resulted in enhanced rate of demethylation of both aminopyrine (CER α half-life) and its monomethyl metabolite (CER β half-life). However the time course of the response to cold stress differs for the two demethylations. The characteristics of the cold-induced enhancement of aminopyrine-CER would appear to differ in several aspects from that reported for phenobarbitone pretreatment. In contrast, ether exposure did not produce any consistent effect on drug metabolizing status of the rat.     

A sensitive gas-chromatographic assay using a nitrogen-phosphorus detector for determination of antipyrine and aminopyrine in biological fluids

A method using gas chromatography with organic nitrogen-sensitive detection is described for measurement of antipyrine and aminopyrine concentrations in biological fluids. The analysis was performed isothermally on 3% SP-2250 DB after alkalinized saliva was extracted into chloroform. Phenacetin served as internal standard. Low oral doses of antipyrine (1.0-1.8 mg/kg) and/or aminopyrine (2 mg/kg) were measured accurately in saliva of normal human subjects. The standard curves for antipyrine and aminopyrine were linear from 0 to 10 microgram/ml. The coefficient of variation, determined at a salivary concentration of 2 microgram/ml, was 1.7% for antipyrine and 2.4% for aminopyrine. Saliva concentrations obtained by this method in normal human subjects after either an oral dose of antipyrine (18 mg/kg) or aminopyrine (9 mg/kg) agreed closely with those determined by the flame ionization gas-chromatographic method used to measure higher concentrations of antipyrine and aminopyrine. Antipyrine (1.8 mg/kg) administered concomitantly with aminopyrine (1 mg/kg or 2 mg/kg) to normal male volunteers prolonged mean saliva antipyrine half-life by about 25-33% compared to values obtained when these same subjects received the same dose of antipyrine alone.     

Estrogen-like activities in Vitex species from China determined by a cell based proliferation assay

Ethanolic extracts of four Chinese medicinally used Vitex species were selected and tested for their estrogen-like activities, using an ERalpha-positive MCF-7 cell based proliferation assay (E-screen assay) and cell cycle analysis (flow cytometry). Vitex negundo displayed the highest estrogenic-like activity, and could be useful in hormone replacement therapy (HRT).     

Formation and distribution of sennosides in Cassia angustifolia, as determined by a sensitive and specific radioimmunoassay

A radioimmunoassay for the quantitation of nanogram-amounts of sennoside B and related compounds in plant extracts is described. The assay makes use of [ (3)H]-8-glucosidorheinanthrone of high specific activity (5.2 Ci/mmol) whose synthesis is reported here. From this material, [ (3)H]-sennoside A and [ (3)H]-sennoside B have also been synthesized. The assay is applied to the analysis of sennoside formation and distribution in CASSIA ANGUSTIFOLIA VAHL. High levels of sennosides in dried leaves and fruits have been observed whereas the seed alone, as well as stems and roots, contain very little sennoside. In flowers, as much as 4-5% of the dry weight consists of sennoside B and other immunoreactive constituents. Sennosides have been found in cotyledons of three day old seedlings in concentrations comparable to that of the mature leaf. Upon dehydration, leaf levels of sennoside B rise steadily, this rise being inversely correlated with the water loss. The absolute levels of sennoside B formed this way are the same as compared to rapid drying at 60 degrees C.     

Device for monitoring 14CO2 in the expired air from beagle dogs: its use in the study of aminopyrine demethylation

1. A device for serial collection of samples for determination of 14CO2 in the expired air of the beagle dog is described. 2. The device has been evaluated using [14C]aminopyrine as a model compound. The rate of 14C excretion in the expired air initially correlated with the plasma concentrations of aminopyrine rather than the plasma concentrations of 14C. 3. The dog demethylated aminopyrine at the slower rate than the rat. Both species demethylate the unchanged drug more readily than subsequent metabolites.     

Estrogenic potencies of several environmental pollutants, as determined by vitellogenin induction in a carp hepatocyte assay.

Estrogenic potencies of several xenoestrogens were determined in vitro, using cultured hepatocytes from a genetically uniform male carp strain (Cyprinus carpio). Estrogenicity was measured as induction of the yolk protein precursor vitellogenin (Vtg), and compared to Vtg induction by 17beta-estradiol (E2). The order of estrogenic potency was: methoxychlor (MXCL) > o,p-DDT > chlordecone approximately/= bisphenol-A approximately/= 4-t-pentylphenol. Estrogenic potencies of these compounds varied from 1 x 10(-3) to 1 x 10(-4) relative to E2. The synthetic estrogen DES had a relative estrogenic potency of 0.5, whereas dieldrin, beta-endosulfan, o,p-DDE, and toxaphene (technical mixture) did not induce vitellogenesis at concentrations up to 100 microM. Experiments in which cells were simultaneously exposed to E2 and these xenoestrogens showed that the Vtg-inducing activities of E2 and 4-t-pentylphenol or bisphenol-A were (partially) additive, whereas E2 antagonized the estrogenic effects of MXCL and o,p-DDT. The effect of cytochrome P4501A (CYP1A)-induction on the estrogenicity of MXCL was studied by co-exposing cells to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD (10 pM) caused a greater than 50-fold induction of CYP1A, measured as ethoxyresorufin O-deethylase (EROD) activity, but Vtg induction by MXCL was not significantly affected. This indicates that CYP1A is not involved in the bioactivation of MXCL to more potent estrogenic metabolites in carp. The CARP-HEP (hepatocyte) assay can detect xenoestrogens with a potency > or = 2 x 10(-5) relative to E2. It allows simultaneous testing of more than 10 compounds for both estrogenic and antiestrogenic effects, which makes it a promising tool for the screening of suspected xenoestrogens.     

Changes in muscle blood flow after smoking a cigarette determined by a new noninvasive method

Summary The pharmacokinetics of the H₂-receptor antagonist famotidine, after oral administration of a 20 mg tablet, has been studied in 10 elderly patients with normal renal function (CL_CR59 ml·min^–1, Mean=80 ml·min^–1), 5 elderly patients with renal insufficiency (CL_CR38 ml·min^–1, Mean=15 ml·min^–1), and 6 healthy young volunteers.Elimination half-life in the elderly patients with renal insufficiency was significantly prolonged compared to the elderly patients with normal renal function and the young volunteers. The correlation coefficient between creatinine clearance and the elimination rate constant of famotidine was 0.672. Mean urinary recovery of unchanged drug up to 24 h in the young volunteers was 44%. The mean renal clearance of famotidine in the young volunteers (270 ml·min^–1) was substantially greater than the creatinine clearance, 128 ml·min^–1, which suggests the possibility of tubular secretion of famotidine.     

Device for monitoring 14CO2 in the expired air from beagle dogs: its use in the study of aminopyrine demethylation

1. A device for serial collection of samples for determination of ¹⁴CO₂ in the expired air of the beagle dog is described.

2. The device has been evaluated using [¹⁴C]aminopyrine as a model compound. The rate of ¹⁴C excretion in the expired air initially correlated with the plasma concentrations of aminopyrine rather than the plasma concentrations of ¹⁴C.

3. The dog demethylated aminopyrine at a slower rate than the rat. Both species demethylate the unchanged drug more readily than subsequent metabolites.     

Stereotyped activities produced by amphetamine in several animal species and man

Summary Experiments with chickens, pidgeons, mice, rats, guinea-pigs, cats, dogs, squirrel-monkeys and chimpanzees show that stereotyped activity can be produced by amphetamine in doses of 1–20 mg/kg in all these species ranging from birds to primates.In man amphetamine in similar dose, i.e. higher than the therapeutic doses, can produce a psychosis, which so closely resembles schizophrenia, that misdiagnoses have been made. All the known symptoms of schizophrenia are reported, including stereotyped activity.This investigation was supported by grants from Knud Højgaards Fond and from the Copenhagen Hospital Administration. The authors want to thank Mrs. Reiko Okada and Mrs. Johanne Mengel for translation of Japanese and Italian literature.     

Microdetermination of propofol in plasma by a rapid and sensitive liquid chromatographic method

A direct and sensitive liquid chromatographic method for the determination of propofol in 50 μl of plasma is described. The separation of the drug and internal standard (methyldopa) was achieved using a 4 μm particle size C₁₈ cartridge (10 cm × 8 mm i.d.) in conjunction with a radial compression system and a C₁₈ precolumn module. The mobile phase consisted of 0.01 M sodium acetate solution (adjusted to pH 3 with acetic acid)-acetonitrile-methanol (37:47.25:15.75, v/v/v) at a flow rate of 2 ml min⁻¹. The compounds were detected in the effluent spectrofluorimetrically with excitation and emission wavelengths of 276 and 310 nm, respectively. After the internal standard had been added, the sample was diluted with 50 μl of hydrochloric acid and centrifuged prior to injection into the chromatograph. The peaks of both propofol and internal standard under these conditions were sharp and symmetrical, and the retention times were 8.2 and 5.15 min, respectively. The peak-height ratio (drug/internal standard) varied linearly (r > 0.9959) with concentration in the ranges 0.002–0.1 and 0.1–10 μg ml⁻¹ and the relative standard deviation was consistently < 5.6%. There was no interference in the assay from the endogenous substance or other concomitantly used drug. This method is currently being used for monitoring propofol in intensive care patients and investigating its pharmacokinetics.     

Kinetics of degradation of diclofenac sodium in aqueous solution determined by a calorimetric method

An isothermal heat conduction microcalorimeter has been used to study the stability of diclofenac sodium both alone and its inclusion complex with beta-cyclodextrin in aqueous solution. The rates of heat evolved during degradation of diclofenac sodium have been measured by a highly sensitive microcalorimetric technique as function of concentration, pH and temperature. The calorimetric accessible data have been incorporated in the equations for determination of rate constants, change in enthalpy and order of reaction. The decomposition of diclofenac sodium both alone and its inclusion complex with beta-cyclodextrin in solution corresponds to a pseudo-first order reaction. The values of rate constants, k's at 338.15 K, (calculated from the variation of heat evolution with the time) for the degradation of diclofenac sodium at pH 5, 6, 7, 8 and its inclusion complex with beta-cyclodextrin at pH 7 are found to be 4.71 x 10(-4), 5.69 x 10(-4), 6.12 x 10(-)4, 6.57 x 10(-4) and 4.26 x 10(-4) h(-1) respectively. There is good agreement between calorimetric determined t(0.5) and literature values. It has been found that beta-cyclodextrin retards the degradation of diclofenac sodium. The kinetic parameters have been calculated for the reaction. The negative entropy of activation suggests the formation of an ordered transition state.     

Metabolism of meperidine in several animal species

Four new meperidine metabolites were identified by GC-MS in the urine of rats, guinea pigs, rabbits, cats, and dogs. In addition to known meperidine metabolites, 4-ethoxycarbonyl-4-phenyl-1,2,3,4-tetrapyridine (dehydronormeperidine; IV, the N-hydroxydehydro derivative of normeperidine (X), the dihydroxy derivative of meperidine (XII), and the dihydroxy derivative of normeperidine (XIII) were identified. The possible role of the N-hydroxy derivative of normeperidine (IX) in the pharmacological interaction of meperidine (I) with MAO inhibitors, seen selectively in the rabbit (and humans), is discussed. Following the administration of the p-hydroxy derivative of meperidine (VII), the major metabolite was conjugated VII. Trace amounts of the p-hydroxy derivative of normeperidine (VIII), the methoxy hydroxy derivative of meperidine (XI), XII, and XIII also were detected as metabolites of VII. The degree of N-demethylation of VII, both in vitro and in vivo, was small.     

Metabolism of BW 1370U87 by crude liver homogenates from several species: An in vitro method for preliminary investigation of species differences in metabolism

We employed broken cell liver preparations in order to investigate potential species-specific differences in the metabolism of BW 1370U87, a new selective and reversible MAO-A inhibitor. The drug metabolizing capacity of crude liver homogenates from rat, dog, cat, monkey, and man was assessed based on the utilization of BW 1370U87 and the appearance of suspected metabolites. When incubated with liver homogenates (37° C) in the presence of a cofactor preparation designed to generate TPNH, BW 1370U87 (1 or 10 μM) was metabolized in a species and time dependent manner. The rate of disappearence of BW 1370U87 was more rapid in dog and cat preparations than those of rat, monkey and man. The appearance of metabolites coincided with the disappearance of BW 1370U87. Three metabolites, identified and synthesized as BW 183U88, BW 380U88, and BW 330U88 appeared in all five species. These metabolites were also found to be selective MAO-A inhibitors both in vitro and ex vivo and may contribute to the overall activity exhibited by the parent molecule.     

Pharmacokinetics of galantamine,a cholinesterase inhibitor,in several animal species

In this publication, single and repeated dose experiments in rats, mice, rabbits and dogs are reported to assess the pharmacokinetics of galantamine (CAS-1953-04-4), a tertiary alkaloid with reversible cholinesterase inhibiting and nicotinic receptor modulatory properties developed for the treatment of Alzheimer's disease in humans. Rats received single i.v. and single and repeated oral administrations of various doses, up to 160 mg/kg/day. In mice, only repeated oral administration of galantamine was investigated, up to 40 mg/kg/day. Galantamine single and repeated oral doses up to 32 mg/kg/day were administered to female pregnant rabbits. Beagle dogs received single i.v. and single and repeated oral administrations of doses up to 8 mg/kg/day. Generally, oral absorption was rapid, with maximal plasma levels reached within 2 h in all species. Absolute oral bioavailability of a gavage dose was high in rat (77%) and dog (78%). In mice and rats, the bioavailability of galantamine administered via the food was lower than of galantamine administered by gavage. Elimination half-life of galantamine was relatively large in rat and dog and smaller in mouse and rabbit. In general, galantamine displayed dose-proportional to somewhat more than dose-proportional kinetics. In rats, plasma levels were lower in females than in males, whereas in mice, females showed higher levels than males. No gender differences were observed in dogs. No relevant differences in exposure to galantamine were found in rats and dogs upon oral administration of galantamine obtained as a natural extract or from chemical synthesis. The exposure to the active metabolite norgalantamine in plasma of the different animal species was low, except in the dog where the steady-state norgalantamine exposure was approximately 75% of galantamine exposure. Galantamine plasma levels after single and repeated administration of 10 mg/kg/day in all species investigated except female rat and rabbit were much higher than mean therapeutic plasma levels of galantamine obtained in humans. The pharmacokinetic profile of galantamine after repeated oral administration in rats was most similar to the profile obtained after repeated administration of 12 mg b.i.d. in man.     

HPLC-MS法研究碘化N-正丁基氟哌啶醇在兔体内的药代动力学

目的:研究碘化N-正丁基氟哌啶醇(F2)在兔体内的药代动力学过程.方法:6只新西兰兔耳缘静脉注射碘化N-正丁基氟哌啶醇(F2)2.0 mg·kg-1后采集血样,用高效液相色谱-质谱(HPLC-MS)联用技术测定血浆药物浓度,并用3p97软件拟合计算药代动力学参数.结果和结论:兔耳缘静脉给药后的血药浓度-时间曲线符合二室开放模型,其主要药动学参数为:分布半衰期T1/2α是0.10 h,消除半衰期T1/2β是6.4 h,曲线下面积AUC为183μg·h-1·L-1,中央室分布容积Vc为4 L,清除率Cl为12.9 L·h-1.HPLC-MS联用方法测定F2血药浓度,灵敏度高,专属性强.     

Analysis of amlodipine in serum by a sensitive high-performance liquid chromatographic method with amperometric detection

An analytical method for a new calcium channel blocking agent, amlodipine, has been developed using high-performance liquid chromatography with electrochemical detection. No compound modification is required for detection and the calibration curve in spiked sera is linear and reproducible over the range 0.2-2.0 ng ml-1. The method has been applied successfully to pharmacokinetics studies in rats and also can be used for other dihydropyridine compounds such as nifedipine and nicardipine.