[Simultaneous determination of three quaternary ammonium muscle relaxants in blood by high performance liquid chromatography-tandem mass spectrometry]

Vecuronium, rocuronium, and pancuronium are widely used as non-depolarizing muscle relaxants. There have been occasional cases of allergic reactions and even death when using such muscle relaxants. Rapid determination of the concentration of these muscle relaxants in blood can provide valuable information for early clinical diagnosis. As quaternary ammonium compounds, these muscle relaxants are highly polar. Hence, they cannot be retained effectively on reversed-phase chromatographic columns with conventional mobile phases. These quaternary ammonium muscle relaxants are mainly separated by ion-pair chromatography. Using an ion-pairing reagent can help improve the retention capabilities of quaternary ammonium muscle relaxants. Nevertheless, the sensitivity of MS detection is significantly decreased because of ionic inhibition caused by the ion-pairing reagent in the mobile phase. Furthermore, ion-pairing reagents can pollute the MS system. A method based on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established for the simultaneous determination of the three quaternary ammonium muscle relaxants in blood. The blood samples were diluted and subjected to high-speed centrifugation. The supernatant was purified on a Bond Elut AL-N solid phase extraction column and then filtered through a 0.45 μm microporous membrane. The quaternary ammonium muscle relaxants were separated on a ZIC-cHILIC analytical column (50 mm×2.1 mm, 3.0 μm) with gradient elution. Acetonitrile and 0.1% formic acid aqueous solution were used as mobile phases. The separated compounds were analyzed by tandem MS with an electrospray ionization (ESI) source in positive and multiple reaction monitoring (MRM) modes. The matrix effects of vecuronium, rocuronium, and pancuronium in blood were 88.1% to 95.4%. The calibration curves for vecuronium, rocuronium, and pancuronium showed good linear relationships in each range, and all correlation coefficients (R2) were > 0.996. The limits of detection of vecuronium, rocuronium, and pancuronium were 0.2-0.8 ng/mL, with the corresponding limits of quantification being 0.5-2.0 ng/mL. The recoveries of vecuronium, rocuronium, and pancuronium were 92.8% to 110.6%, with relative standard deviations (RSDs) of 3.2%-9.4%. This method is sensitive, accurate, and easy to operate, and it can be used to rapidly determine vecuronium, rocuronium, and pancuronium in blood.

Lipid solubility of pancuronium and vecuronium determined by n-octanol/water partitioning

We have measured the n-octanol/water distribution coefficients at 37 degrees C of two steroidal myoneural blockers (pancuronium and vecuronium) and of their 3-hydroxy metabolites over a pH range from 1.5 to 11. Pancuronium was found not to be lipid soluble. The mean distribution coefficient of 3-hydroxy vecuronium at pH = 7.4 was 0 and that of vecuronium 0.12 (SD 0.1). Distribution coefficients of the parent drug showed a slightly greater lipid solubility than the metabolite (11.37 (2.91) and 9.53 (3.44), respectively (mean t0.05 x SE)). Because of its lipid solubility, vecuronium may penetrate into lipid structures.

A novel class of antitumour agents. I. Chemistry and animal experiments

Newly synthesized tertiary amino steroids, among them 2 beta,16 beta-dipiperidino-5 alpha-androstane-3 alpha,17 beta-diol dipivalate (DAP), were tested in three animal species as to their antitumour activity against transplantable tumours. The acute toxicity of DAP was similar to that of cyclophosphamide and considerably lower than vinblastine. Rats with Walker ascites, treated intraperitoneally with DAP, survived up to one year without ascites; untreated animals died within 10 days of transplantation. Intragastric and intraperitoneal application of DAP caused side effects suggesting a local toxicity.