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  • 1
    Electronic Resource
    Electronic Resource
    Dose-dependent absorption and elimination of gamma-hydroxybutyric acid in healthy volunteers (1993)
    Springer
    European journal of clinical pharmacology 45 (1993), S. 353-356 
    Details
    ISSN: 1432-1041
    Keywords: Gamma-hydroxybutyric acid ; pharmacokinetics ; dose-proportionality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Gamma-hydroxybutyric acid (GHB) is effective in treatment of the alcohol and opiate withdrawal syndromes. Its absorption and disposition kinetics have been studied in 8 healthy male volunteers following oral administration of single doses of 12.5, 25 and 50 mg kg−1. The AUC increased disproportionately with the dose and so the apparent oral clearance decreased significantly as the dose was increased, whereas the terminal half-life and mean residence time increased. The peak plasma concentrations normalised to the lowest dose fell significantly with increasing doses, whilst the corresponding peak times increased. These findings suggest that both the oral absorption and the elimination of GHB are capacity-limited processes. GHB did not bind to significant extent to plasma proteins over the therapeutic concentration range. The pharmacokinetic parameters in healthy volunteers were not significantly different from those previously observed in alcohol-dependent patients with compensated alcoholic liver disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00265954
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of moderate or severe liver dysfunction on the pharmacokinetics of γ-hydroxybutyric acid (1996)
    Springer
    European journal of clinical pharmacology 50 (1996), S. 305-310 
    Details
    ISSN: 1432-1041
    Keywords: Key words Gamma-hydroxybutyric acid; pharmacokinetics ; liver dysfunction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objectives: To assess the effect of moderate or severe liver dysfunction on the pharmacokinetics of γ-hydroxybutyric acid (GHB). Methods: The absorption and disposition kinetics of GHB were studied in eight cirrhotic patients without ascites (Child’s class A) and eight cirrhotic patients with ascites (Child’s class C), after administration of a single oral dose of 25 mg⋅kg−1. The liver metabolic function of each patient was evaluated by measuring antipyrine clearance and the formation rate of the lidocaine metabolite monoethylglycinexylidide (MEGX). Results: Compared to those previously determined in eight healthy control subjects given the same GHB dose, mean AUC values were double or greater in the cirrhotic patients. Accordingly, apparent oral clearance was markedly reduced (from 9.1 to 4.5 and 4.1 ml⋅min−1⋅kg−1 in nonascitic and ascitic patients, respectively). Terminal half-life (t1/2), was significantly longer in nonascitic patients than in control subjects (32 vs 22 min). A further significant prolongation of t1/2, most likely due to an increased distribution volume, was observed in patients with ascites (56 min). Nonetheless, GHB plasma concentrations fell to either undetectable or negligible levels by the end of the usual dosing intervals (6–8 h). More limited changes were noted in the absorption parameters. The peak level (Cmax) increased only in nonascitic patients, but not proportionally to the increase in AUC. The time to Cmax increased from 30 to 45 min in both cirrhotic groups. These findings are consistent with a slowed rate of GHB absorption in cirrhotic patients. Adverse effects were similar, for intensity and duration, to those recorded in healthy volunteers, i.e., mild and transient. Conclusions: Although liver cirrhosis causes significant modifications of GHB disposition kinetics, the increase in t1/2 is not such as to cause drug accumulation on repetitive dosing. However, in consideration of the higher mean plasma levels observed in cirrhotic patients, it appears wise to keep the initial GHB daily dose at the lower end of the therapeutic range and to carefully monitor the patients if upward dose adjustments are required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050113
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  • 3
    Electronic Resource
    Electronic Resource
    Therapeutic gamma-hydroxybutyric acid monitoring in plasma and urine by gas chromatography-mass spectrometry
    Amsterdam : Elsevier
    Journal of Pharmaceutical and Biomedical Analysis 11 (1993), S. 483-487 
    Details
    ISSN: 0731-7085
    Keywords: GC-MS. ; Gamma-hydroxybutyric acid ; therapeutic drug monitoring
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0731-7085(93)80161-S
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  • 4
    Electronic Resource
    Electronic Resource
    Laser induced vaporization mass spectrometry of a high melting multidentate chelating ligand and its Ni(II) bisdeprotonated complex
    Amsterdam : Elsevier
    Inorganica Chimica Acta 148 (1988), S. 151-157 
    Details
    ISSN: 0020-1693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0020-1693(00)87495-2
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  • 5
    Electronic Resource
    Electronic Resource
    Simultaneous identification of amphetamine and its derivatives in urine using HPLC-UV (1993)
    Springer
    International journal of legal medicine 105 (1993), S. 265-269 
    Details
    ISSN: 1437-1596
    Keywords: Amphetamines ; Reversed-phase liquid chromatography ; UV detection ; Amphetamine ; Reversed-phase-Flüssigkeitschromatographie ; UV-Detektion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Description / Table of Contents: Zusammenfassung Eine HPLC-UV-Methode zur gleichzeitigen Bestimmung von Amphetamin, Methamphetamin, 3,4-Methylendioxyamphetamin (MDA) und 3,4-Methylendioxymethamphetamin (MDMA) im Urin wird beschrieben. Vorgestellt wird eine Schnellextraktion der 4 Amphetamine über Extrelut-3-Säulen und eine Derivatisierung mit Natrium-1,2-naphthochinon-4-sulfonat (NQS) um hochchromophore UV-VIS-Derivate zu erhalten. Abschließend erfolgt eine HPLC-Analyse mittels einer reversed phase Technik (Ionenpaar) mit Detektion des Eluats bei 480 nm. Die Struktur der NQS-Derivate wird durch Massenspektrometrie charakterisiert. Die Wiederfindungsraten der Amphetamine liegen bei Konzentrationen von 300 ng/ml bei 80–85%. Die Nachweisgrenze liegt für alle Derivate bei 40–60 ng/ml (S/N-Verhältnis = 10). Die Trennung der NQS-derivatisierten Amphetamine gelingt gut, die Methode ist einfach, schnell, empfindlich und spezifisch genug für die Bestätigung vorläufiger Screening-Resultate, wie sie mit Hilfe von Immunoassays erhalten werden.
    Notes: Summary An HPLC-UV method for the simultaneous identification of amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA) in urine is described. It includes a rapid extraction procedure of the 4 analogs from urine using Extrelut 3 columns, derivatization with sodium 1,2-naphthoquinone-4-sulphonate (NQS) to obtain highly chromophoric UV-VIS derivatives, and a final HPLC analysis using an ion-pair reversed-phase technique with eluent monitoring at 480 nm. Structural characterization of the derivatives obtained by mass spectrometry is reported. Recoveries of the amphetamines were in the range 80–85% at concentrations of 300 ng/ml. Practical detection limits were 40–60 ng/ml (S/N ratio = 10) for all derivatives. The chromatographic peaks of the NQS derivatized amphetamines are fairly narrow and well resolved. The method is simple, rapid, quite sensitive, and specific for convenient confirmation of preliminary positive results obtained with immunoassays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01370383
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  • 6
    Electronic Resource
    Electronic Resource
    Proficiency testing for psychoactive substances in Italy (1999)
    Springer
    International journal of legal medicine 113 (1999), S. 50-54 
    Details
    ISSN: 1437-1596
    Keywords: Key words Proficiency testing ; Quality control ; Analytical toxicology ; Psychoactive substances
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Notes: Abstract This paper describes the general design and main results of the Italian proficiency testing program for the analysis of psychoactive substances in urine, a long-term initiative created in 1995 on an educational basis and characterized by an innovative internet-based service for data exchange between laboratories and the organizing body. Batches of six urine samples, validated by reference laboratories, are sent every 3 months to participating laboratories, which may choose which classes of substances to test from those planned by the program panel and, within those classes, which type of analytical commitment to work on: identification of just one class (Option 1), identification of single substances (Option 2), or identification and quantification of single substances (Option 3). Comprehensive periodical reports and annual reports are provided to participants with evaluation of their performance and an annual workshop is organized to discuss technical-scientific topics related to clinical, forensic and analytical toxicology. About 200 laboratories currently participate in the program and a total of 67,059 analyses have been carried out since 1995. The mean percentage of correct results was 96.8%, with a yearly improvement of about 0.4%. The best average false positive and false negative rates were obtained for methadone (0.2% and 2.1% respectively) and cocaine (0.3% and 2.2%). The worst average false positive rates were obtained for amphetamines and opiates (3.2% and 5.0%) and worst average false negative rates for amphetamines, barbiturates and cannabinoids (17.4%, 30.7% and 19.9%).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004140050279
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  • 7
    Electronic Resource
    Electronic Resource
    Structural characterization of two isomeric dimethoxyindoles of biological interest, using high- and low-energy collisional spectroscopy (1989)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 3 (1989), S. 413-416 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: It is not possible to distinguish isomers of biologically important dimethoxyindoles using electron-ionization mass spectra, but they may be distinguished by collisionally activated dissociation. In particular, energy-resolved mass spectrometry yields the best data for distinguishing between these isomers.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290031202
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  • 8
    Electronic Resource
    Electronic Resource
    Chromophoric Derivatives of Amphetamine Analogues: Strucutural Characterization by Electron Impact Mass Spectrometry (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 27 (1992), S. 1284-1286 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210271122
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