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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 26 (1984), S. 613-617 
    ISSN: 1432-1041
    Keywords: atropine ; radioreceptor assay ; radioimmunoassay ; serum levels ; pharmacokinetics ; assay comparison
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A membrane suspension prepared from rat brain was able to bind the potent muscarinic antagonist quinuclidinyl benzilate (QNB). The KD for binding was 0.48 nM and Bmax was 1.42 pmol/mg protein. Atropine competitively inhibited the binding of tritiated QNB to muscarinic receptors. This new radioreceptor assay (RRA) for atropine has been compared with a radioimmunoassay (RIA) for atropine. The RRA measures only the active component of atropine, 1-hyscyamine and in this respect it differs from the RIA. As little atropine as 1.25 ng/ml (4.33 nmol/l) in a 25 µl serum sample could be reliably assayed by the RRA. Using both assay techniques the pharmacokinetics of atropine was studied after a single 0.02 mg/kg i.v. dose given to 8 anaesthetized patients. The half-life calculated by the RRA was 3.7±2.3 h (m ± SD) and by the RIA 4.3±1.7 h. Both the volume of distribution and the total clearance were higher according to the RRA than the RIA: 3.9±1.5 vs 1.7±0.71/kg and 15.4±10.3 vs 5.9±3.6 ml/min/kg, respectively. The AUC measured by the RRA and RIA was 29.8±18.9 and 103.9±110.7 µg·h/l, respectively. The differences in the pharmacokinetics according to the 2 methods are presumably due to preferential tissue uptake of the l-form.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 25 (1983), S. 247-251 
    ISSN: 1432-1041
    Keywords: midazolam ; CSF penetration ; pharmacokinetics ; benzodiazepines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The passage of midazolam, a new benzodiazepine derivative with highly water-soluble salts, into cerebrospinal fluid (CSF) was studied after a single oral dose of 15 mg (n=23), a single i.m. injection of 0.075 or 0.150 mg/kg (n=8), or a single i.v. dose of 0.075 mg/kg (n=26). Contrary to previous studies of diazepam and flunitrazepam, the rapid clinical effect of midazolam cannot be explained by rapid passage into human lumbar CSF. In only four cases following intravenous injection was there a measurable amount of drug in lumbar CSF (lower limit of assay sensitivity=2 ng/ml). After both oral (n=10) and intramuscular (n=8) administration, midazolam was rapidly absorbed, with attainment of the peak serum level after about 0.5 h. The pharmacokinetic parameters following i.v. injection of midazolam (n=6) explain its rapid but brief duration of action.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 25 (1983), S. 639-641 
    ISSN: 1432-1041
    Keywords: Lidocaine ; CSF penetration ; monoethylglycinxylidide ; glycinxylidide ; pharmacokinetics ; serum protein binding ; membrane permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Penetration into lumbar cerebrospinal fluid (CSF) of lidocaine and its active desethylated metabolite, monoethylglycinxylidide (MEGX), has been studied in 10 neurological patients after a single subcutaneous injection of 2 mg/kg prior to lumbar puncture. An HPLC method was used to assay lidocaine, MEGX and glycinxylidide (GX) in serum and CSF. The serum protein unbound fraction of lidocaine was determined by equilibrium dialysis. The mean peak serum lidocaine concentration was found 25 minutes after injection, and the corresponding peak CSF level occurred after 70 min. A similar slow penetration of MEGX into CSF was observed, which indicates low membrane permeability for these two agents. No GX was found. The steadily increasing CSF lidocaine/serum total lidocaine ratio throughout the period of study up to 120 min and the higher level in CSF than the corresponding unbound fraction of the total serum lidocaine indicate that serum protein binding is not the sole determinant of the penetration of lidocaine into lumbar CSF. Rapid accumulation in brain tissue and diffusion back into cerebral extracellular fluid and to lumbar CSF may also occur. The apparent slow membrane penetration of lidocaine and its desethylated metabolite may be one reason for the difficulty of controlling lidocaine infusion rates according to therapeutic effectiveness and side-effects.
    Type of Medium: Electronic Resource
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