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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of medicinal chemistry 12 (1969), S. 940-941 
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-904X
    Keywords: monoamine oxidase inhibitors ; tranylcypromine ; N-(2-cyanoethyl)tranylcypromine ; catecholamines ; brain ; prodrug
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The disposition of the N-cyanoethyl analogue of tranylcypromine (TCP) and the TCP formed from it have been studied in the rat brain following intraperitoneal (ip) administration (0.1 mmol/kg) and the resultant data compared with those obtained following an equimolar dose of TCP. Brain concentrations of the neurotransmitter amines dopamine (DA) and noradrenaline (NA) have also been determined, as well as the percentage inhibition of monoamine oxidase (MAO) types A and B. Our results indicate that the N-cyanoethyl analogue may be a useful prodrug of TCP, providing lower but more sustained concentrations of TCP in brain. Brain levels of DA were increased in a similar pattern after CE-TCP or TCP. Brain levels of NA were decreased by TCP at most time intervals, while CE-TCP produced a much less pronounced effect. Both CE-TCP and TCP inhibited MAO-A and MAO-B, with maximum inhibition occurring 60 min after CE-TCP dosing and 30 min after dosing with TCP, times at which brain concentrations of CE-TCP and TCP were at the maximum.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 7 (1990), S. 274-279 
    ISSN: 1573-904X
    Keywords: hydralazine ; food–drug interaction ; Michaelis–Menten kinetics ; bioavailability ; pharmacokinetics ; dog ; animal model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The intravenous and oral dose-dependent pharmacokinetics of hydralazine and the effect of concurrent administration of food with hydralazine in dogs were evaluated for comparison with published human data. Four dogs were given intravenous and oral doses of hydralazine at 0.25, 1.0, 2.5, and 4.0 mg/kg. In addition, the oral 2.5 mg/kg dose was given with a meal. Blood samples were collected at appropriate intervals and analyzed for hydralazine. Pharmacokinetic analysis showed that AUCoral/ dose (5552 to 13218 mg-min/ml) and F (0.36 to 0.77) increased significantly with dose, indicating saturation of first-pass metabolism, as is seen in humans. Total-body clearance (70 ml/min/kg) and steady-state volume of distribution (9 L/kg) were similar to human values. The bioavailability of hydralazine in the dog was decreased by 63% when the dose was given with a meal, which is comparable to some human data. It was concluded that the dog may be a useful model in which to study mechanisms of the hydralazine-food interaction.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 7 (1990), S. 504-507 
    ISSN: 1573-904X
    Keywords: quantification ; lidocaine metabolites ; conjugates ; N-ethylglycyl-2,6-xylidide ; glycyl-2,6-xylidide ; 4-hydroxy-2,6-xylidine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A method has been developed to quantify three lidocaine metabolites, N-ethylglycyl-2,6-xylidide (MEGX), glycyl-2,6-xylidide (GX), and 4-hydroxy-2,6-xylidine (4-OH-XY), and their conjugates in pooled human urine using enzymic hydrolysis. The commonly used enzymes, pure β-glucuronidase, sulfatase, and a mixture of the two, were tested for their efficiencies in hydrolyzing the conjugates. Initially, it was found that 4-OH-XY was highly unstable after it was released from conjugates by β-glucuronidase and the enzyme mixture. This problem was corrected by purging the sample with nitrogen prior to incubation. It has been determined that 4-OH-XY is present in human urine exclusively as its glucuronide. The percentage of MEGX in free and in conjugated forms (glucuronide, sulfate, and others) are 44.9 ± 6.8,16.6 ± 4.5, 6.6 ± 1.8, and 31.9 ± 4.4, respectively. GX was present mostly in the free form (90.6 ± 10.5%).
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  • 5
    ISSN: 1573-904X
    Keywords: ibuprofen enantiomers ; enantiomeric inversion ; presystemic inversion ; gut metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ibuprofen (IB) is a racemic drug and is administered as such. While activity is due mainly to the S enantiomer, pharmacokinetic interpretations, as well as criteria to assess the bioequivalence of IB formulations, are based on measurements of the total (S + R) drug concentrations. IB enantiomers possess different disposition properties mainly as a result of R-to-S isomeric bioinversion. Inversion is maximal during the absorption phase, suggesting, perhaps, involvement of a presystemic process. This concept was evaluated in healthy subjects by crossover administration of four IB tablets having different absorption rates. The plasma concentrations of the individual isomers were measured using a stereospecific gas chromatographic assay. Differences among the products were insignificant with respect to the extent to the absorption. The S:R concentration ratios rose for 4 to 6 hr and then remained relatively unchanged. This observation was consistent with equal terminal t 1/2 values for the enantiomers. There were significant differences between the peak times (T max) of the products. The S:R ratios of the concentrations at T max of S and AUC also differed; significant positive correlations were found between T max and the S:R ratios of C max. Thus the extent of R-to-S inversion, and hence the potency of a racemic dose of IB, may be absorption rate dependent.
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  • 6
    ISSN: 0899-0042
    Keywords: chirality ; fluoxetine ; norfluoxetine ; desipramine ; iprindole ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The antidepressant fluoxetine (FLU) and its N-demethylated metabolite, norfluoxetine (NFLU), each contains a chiral center. The combination of FLU and desipramine (DMI), another antidepressant, has been reported to be useful in treatment of depression, to dramatically increase plasma levels of DMI and also to produce more rapid β-adrenergic receptor down-regulation in brain than caused by DMI alone. We have now begun studies on the effects of this drug combination on the levels of FLU and NFLU enantiomers in the rat. In addition, the combination of FLU and iprindole (IPR) was also investigated. Male Sprague-Dawley rats were treated intraperitoneally with either normal saline vehicle, DMI (5 mg/kg/day), (R,S)-FLU (10 mg/kg/day) or DMI (5 mg/kg/day) + (R,S)-FLU (10 mg/kg/day) for 4 days. Following the last treatment, 24 h urine samples were collected. Rats were sacrificed and brains were removed. For the IPR study, rats were pretreated with either saline or IPR-HCl (11.2 mg/kg) and then treated 1 h later with (R,S)-FLU. After 5 h, the rats were sacrificed and brains were removed. Brain and urine samples were analyzed by gas chromatography with electron-capture detection for free (R)- and (S)-FLU and (R)- and (S)-NFLU after extraction and reaction with (-)-(S)-N-(trifluoroacetyl)prolyl chloride. The results from the brains of the rats treated with DMI/FLU indicate that levels of the enantiomers of both FLU and NFLU were significantly increased over those seen in the animals receiving (R,S)-FLU alone. In the IPR/FLU treated rats, an increase in the brain levels of both (R)- and (S)-FLU was noted when compared with rats receiving (R,S)-FLU alone; however, there appeared to be no increase in the brain levels of NFLU enantiomers. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1980), S. 327-330 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas chromatographic and mass spectrometric behavior of 2-amino-1-iodo-3-phenylpropane (iodoamphetamine) was investigated. It was determined that the compound is unstable under the gas chromatographic mass spectrometric conditions used, undergoing a number of reactions and rearrangements. When iodoamphetamine hydrochloride was neutralized with base and the product examined by gas chromatography two peaks resulted. The major peak was identified as 2-benzylaziridine formed by the expulsion of HI from iodoamphetamine. The minor peak corresponded to iodoamphetamine itself. When an ethanolic solution of iodoamphetamine hydrochloride was injected into the gas chromatograph, however, three peaks were observed. Two of the three peaks had retention times identical to those identified previously. The other peak was concluded to be a chloro compound resulting from the opening of the aziridine ring with chloride ion.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 17 (1997), S. 227-233 
    ISSN: 1573-6830
    Keywords: haloperidol ; cytochrome P450 ; drug metabolism ; isoenzyme ; drug–drug interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Human cytochrome P450 (CYP) isoenzymes expressed in a human cell line were used to elucidate their involvement in the metabolism of haloperidol (HAL). 2. It was found that CYP3A4 catalyzes the metabolism of HAL to HAL 1,2,3,6-tetrahydropyridine (HTP). HTP is further metabolized to HAL pyridinium (HP+) by both CYP3A4 and CYP2D6. 3. CYP3A4 and CYP2D6 are also responsible for the N-dealkylation of HAL. The N-dealkylation of reduced HAL (RH) was observed, which is catalyzed by CYP3A4. In addition, CYP3A4 also catalyzes the oxidation of RH back to HAL. 4. These results are discussed in terms of the metabolic interactions of HAL with other drugs and how this knowledge may be used to reduce the movement disorders induced by HAL.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 19 (1999), S. 325-354 
    ISSN: 1573-6830
    Keywords: drug metabolism ; cytochromes P450 ; monooxygenases ; polymorphism ; CYP2D6 ; CYP2C19 ; CYP2C9 ; amino acid sequences ; defective genes ; phenotyping ; genotyping ; ethnic differences in drug metabolism ; CYP enzyme inhibitors ; CYP enzyme substrates ; drug/drug interactions ; poor metabolizers ; extensive metabolizers ; ultrarapid metabolizers ; diet ; age ; cancer ; Parkinson's disease ; schizophrenia ; Alzheimer's disease ; epilepsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. The cytochrome P450 monooxygenases, CYP2D6, CYP2C19, and CYP2C9, display polymorphism. CYP2D6 and CYP2C19 have been studied extensively, and despite their low abundance in the liver, they catalyze the metabolism of many drugs. 2. CYP2D6 has numerous allelic variants, whereas CYP2C19 has only two. Most variants are translated into inactive, truncated protein or fail to express protein. 3. CYP2C9 is expressed as the wild-type enzyme and has two variants, in each of which one amino acid residue has been replaced. 4. The nucleotide base sequences of the cDNAs of the three polymorphic genes and their variants have been determined, and the proteins derived from these genes have been characterized. 5. An absence of CYP2D6 and/or CYP2C19 in an individual produces a poor metabolizer (PM) of drugs that are substrates of these enzymes. 6. When two drugs that are substrates for a polymorphic CYP enzyme are administered concomitantly, each will compete for that enzyme and competitively inhibit the metabolism of the other substrate. This can result in toxicity. 7. Patients can be readily phenotyped or genotyped to determine their CYP2D6 or CYP2C19 enzymatic status. Poor metabolizers (PMs), extensive metabolizers (EMs), and ultrarapid metabolizers (URMs) can be identified. 8. Numerous substrates and inhibitors of CYP2D6, CYP2C19, and CYP2C9 are identified. 9. An individual's diet and age can influence CYP enzyme activity. 10. CYP2D6 polymorphism has been associated with the risk of onset of various illnesses, including cancer, schizophrenia, Parkinson's disease, Alzheimer's disease, and epilepsy.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 7 (1987), S. 271-290 
    ISSN: 1573-6830
    Keywords: tranylcypromine ; 4-fluorotranylcypromine ; monoamine oxidase ; norepinephrine ; dopamine ; 5-hydroxytryptamine ; ring hydroxylation ; gas chromatography ; high-pressure liquid chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The 4-fluoro analogue of the monoamine oxidase-inhibiting antidepressant tranylcypromine was compared to the parent drug with regard to the following: inhibition of monoamine oxidases A and Bin vitro andex vivo; levels of both drugs in brain, liver, and blood after injection of equimolar doses; and effects on brain levels of the amines 2-phenylethylamine, tryptamine, norepinephrine, dopamine, and 5-hydroxytryptamine. 2. 4-Fluorotranylcypromine was found to be 10 times more potent than tranylcypromine at inhibiting monoamine oxidases A and Bin vitro in rat brain homogenates. 3. After administration (0.1 mmol/kg, ip), 4-fluorotranylcypromine attained higher brain and liver levels and provided greater availability than did tranylcypromine after the injection of an equimolar amount. 4. At the dose employed, theex vivo monoamine oxidases A and B inhibitory profiles in brain and liver over a 24-hr period following tranylcypromine and 4-fluorotranylcypromine treatment were not different from each other. 5. Although the drugs had similar effects on inhibition of brain MAOex vivo, they differed from one another at several time intervals in the increases in concentrations of 2-phenylethylamine, tryptamine, norepinephrine, dopamine, and 5-hydroxytryptamine produced in brain. 6. In conclusion, fluorination of tranylcypromine in the 4 position of the phenyl ring produced a drug which was more potent than the parent drug at inhibiting MAOin vitro and attained higher levels in brain than did tranylcypromine itself after intraperitoneal injection of equimolar amounts of the drugs. 4-Fluorotranylcypromine increased the concentrations of trace amines, catecholamines, and 5-hydroxytryptamine in brain at most time intervals following intraperitoneal injection, and at some time intervals there were differences from tranylcypromine with regard to the amine concentrations produced.
    Type of Medium: Electronic Resource
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