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  • 1
    ISSN: 1432-1041
    Keywords: haloperidol (HAL) ; reduced haloperidol (RHAL) ; interconversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The interconversion between haloperidol (HAL) and reduced haloperidol (RHAL) was examined following their separate administration in low (5 mg) single oral doses to 15 young healthy male volunteers in a crossover design. Using an ultrasensitive HPLC method plasma concentrations of HAL and RHAL were monitored over a period of one week following each administration. Except in one case, both the analytes were found in the plasma of all the volunteers following each administration, thereby indicating interconversion of the two compounds. Comparison of the AUC(0-t) ratios of RHAL/HAL and HAL/RHAL following administration of HAL and RHAL, respectively, revealed that the interconversion favours the reduction of HAL to RHAL. The disposition of HAL following administration of RHAL appears to be limited by its rate of formation and the disposition of RHAL following administration of HAL, on the other hand, is much slower than that of the parent compound.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of the tristrifluoroacetyl derivative of α-methyldopamine and the bistrifluoroacetyl derivative of 3-O-methyl-α-methyldopamine contain important ions which can be rationalized by two alternative fragmentation pathways. These ambiguities were resolved by means of a simple chemical derivatization technique. The labile phenolic ester groups were hydrolyzed and subsequently re-esterified by reaction with chlorodifluoroacetic anhydride in the presence of ethyl acetate thereby labeling ions containing ester group(s) in the mass spectra with the diagnostic chlorine isotope ratio. This resulted in the addition of 16/18 mass units to the weights of the ions for each fluorine atom replaced by chlorine. Since it was easy to distinguish loss of the mass of a neutral molecule of trifluoroacetamide (113 mass units) from the ions of a chlorodifluoroacetoxy radical (129 mass units), the elimination of trifluoroacetamide was distinguished from that of trifluoroacetoxy radical. Derivatives were also prepared in which the chlorine label was located on the N-acyl function. The mass spectra of the chlorine labeled compounds showed that the major fragmentation pathway of tristrihaloacetyl-α-methyldopamine and bistrihaloacyl-3-O-methyl-α-methyldopamine is by loss of a neutral molecule of trihaloacetamide.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A gas chromatographic mass spectrometric assay using selected ion monitoring is described which permits the determination of trifluoperazine in plasma at concentrations ranging from 0.078 to 5.0 ng ml-1. It relies on the extraction of trifluoperazine and the internal standard, prochlorperazine or the tetradeuterated analogue of trifluoperazine, form basified plasma with a n-pentane/2-propanol solvent mixture. Following the evaporation of organic solvent, the residue is reconstituted in a small volume of methanol. Suitable aliquots were anlysed by the combined technique of gas chromatography/electron impact mass spectrometry with a data system. The described procedure is specific and enables the quantitation of 78 pg ml-1 of the drug with a coefficient of variation 〈7%. The method has demonstrated sufficient sensitivity to permit pharmacokinetic and bioavailability studies after a single 5 mg oral dose.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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