Determination of decapeptide LXT-101 in plasma by HPLC-MS/MS and its pharmacokinetics in Beagle dogs / 药学学报

This paper developed a sensitive and specific liquid chromatography-electrospray ionization mass spectrometry (HPLC-MS/MS) method for the determination of decapeptide LXT-101 in Beagle dog plasma. Plasma samples spiked with internal standard (IS) were treated with acetonitrile to precipitate the protein. Selected reaction monitoring (SRM) using the precursor --> product ion combinations of m/z 472.1-->587.9 and m/z 502.8-->633.8 were used to quantify LXT-101 and IS, respectively. The linear calibration curves were obtained in the concentration range of 0.5 - 500.0 ng x mL(-1). The limit of quantification (LOQ) was 0.5 ng x mL(-1). The inter-day and intra-day precision (RSD) across three validation run over the entire concentration range was below 10.9%, and the accuracy (RE) was within +/- 1.8%. The main pharmacokinetic parameters of LXT-101 after muscle injection of 20 microg x kg(-1) were as follows, AUC(0-t): (176.8 +/- 116.7) microg x h x L(-1), MRT(0-t): (2.52 +/- 0.53) h, T(1/2): (1.4 +/- 0.3) h; CL: (0.16 +/- 0.09) L x h(-1) x kg(-1), and Vd: (0.30 +/- 0.16) L x kg(-1), respectively. The method is proved to be specific, sensitive and suitable for the investigation of LXT-101 pharmacokinetics in Beagle dog.

Identification of the metabolites of penehyclidine hydrochloride raceme in rats by LC-MS/MS and ion cluster / 药学学报

<p><b>AIM</b>To study the metabolites of penehyclidine hydrochloride (PH) raceme, a new anticholinerigic drug invented by the Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences.</p><p><b>METHODS</b>Three healthy rat urine samples were collected within 24 h after a single i.m. dose of PH raceme and PH-d5 [(5 + 5) mg.kg-1] simultaneously. The eight metabolites of PH raceme were identified by the methods of LC-MS/MS, GC-MS, FAB-MS and the stable isotope ion cluster. Mass spectrometry was operated in the positive mode for the method of LC-MS/MS.</p><p><b>RESULTS</b>M1 and M1* were identified as the oxygenated products of PH in the cyclopentyl group; M2 and M2* were as the hydroxylated products of PH in the cyclopentyl group; M3 and M3* were as the oxygented and hydroxylated products of PH at the meta-position of cyclopentyl group; M4 and M4* were identified as the dihydroxylated metabolites of PH, the hydroxylated position were at the cyclopentyl group and quiniuclidinol ring of PH. Among them, M1 and M1*, M2 and M2*, M3 and M3*, M4 and M4* were the isomers of each other.</p><p><b>CONCLUSION</b>These characteristics can be used for future structure elucidation in studies of the metabolites of PH optical isomers. The structure data of PH metabolites provide important information for the clinical use and for developing better anticholinerigic drug.</p>