title: Quantification of the neuromuscular blocking agent rocuronium and its putative metabolite 17-desacetylrocuronium in heparinized plasma by capillary gas chromatography using a nitrogen sensitive detector.
abstract: We have developed a sensitive and specific capillary GC (cGC) assay for the quantification of the quarternary aminosteroidal compound rocuronium (roc), a neuromuscular blocking agent, and its putative metabolite 17-desacetylrocuronium (17OH-roc), using 3-desacetylvecuronium (3OH-vec) as an internal standard (I.S.). This novel method has been applied to a pharmacokinetic study with roc, monitoring sixty patients who were classified according to four different body mass index (BMI) groups. The isolation of these drugs from plasma was carried out using a dichloromethane liquid-liquid extraction after ion-pairing of the positively charged ammonium compounds with iodide. To achieve thermal stability, tert.-butyldimethylsilyl-ethers were formed at the 3OH- and 17OH-steroidal positions by reaction with N-methyl-N-(tert.-butyldimethylsilyl)-trifluoroacetamide at 70 degrees C overnight. An automated cGC system fitted with a nitrogen sensitive detector with a specially prepared glass phase bead and a computer controlled data handling system was used to analyze and quantify the compounds, which were separated on a DB1 capillary column with helium as the carrier gas and a temperature program ranging from 120 to 300 degrees C. The method is linear for 50-6400 ng/ml for roc and 80-6400 ng/ml for 17OH-roc. The detection limits were 10 ng/ml for roc and 50 ng/ml for 17OH-roc. The lower limit of quantification was 50 ng/ml for roc and 80 ng/ml for 17OH-roc. Intra-assay coefficients of variation (C.V.s) were 10% and 15% and the inter-assay C.V.s 8-18% and 16-21% for roc and 17OH-roc, respectively.
authors.affiliation: Institute for Clinical Chemistry and Pathobiochemistry, Klinikum rechts der Isar, Technical University of Munich, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Probst
authors.forename: M
authors.initials: M
authors.lastname: Blobner
authors.forename: P
authors.initials: P
authors.lastname: Luppa
authors.forename: D
authors.initials: D
authors.lastname: Neumeier
mesh_terms: D000732:Androstanols / Q000008:administration & dosage / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D000925:Anticoagulants / Q000494:pharmacology; D001247:Asthenia / Q000097:blood; D002849:Chromatography, Gas / Q000379:methods*; D002940:Circadian Rhythm; D005260:Female; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D007262:Infusions, Intravenous; D008875:Middle Aged; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D009765:Obesity / Q000097:blood; D015203:Reproducibility of Results; D000077123:Rocuronium; D012680:Sensitivity and Specificity; D013851:Thinness / Q000097:blood; D013997:Time Factors
chemical_list: D000732:Androstanols; D000925:Anticoagulants; D003473:Neuromuscular Nondepolarizing Agents; D006493:Heparin; D000077123:Rocuronium