Discovery, stereospecific characterization and peripheral modification of 1-(pyrrolidin-1-ylmethyl)-2-[(6-chloro-3-oxo-indan)-formyl]-1,2,3,4-tetrahydroisoquinolines as novel selective κ opioid receptor agonists.

A novel series of 1-(pyrrolidin-1-ylmethyl)-2-[(3-oxo-indan)-formyl]-1,2,3,4-tetrahydroisoquinoline derivatives maj-3a-maj-3u were synthesized and evaluated in vitro for their binding affinity at κ-opioid receptors. Maj-3c displayed the highest affinity for κ-opioid receptors (Ki = 0.033 nM) among all the compounds evaluated. Furthermore, all four stereoisomers of compound 3c were prepared, and (1S,18S)-3c was identified as the most potent (Ki = 0.0059 nM) κ-opioid receptor agonist among the four stereoisomers. Maj-3c produced significant antinociception (ED50 = 0.000406 mg kg(-1)) compared to U-50,488H and original BRL 52580 in the acetic acid writhing assay, but its strong sedative effect (ED50 = 0.000568 mg kg(-1)) observed in the mouse rotation test reduced its druggability. To minimize the central nervous system side effects, a series of hydroxyl-containing analogs of maj-3c were synthesized, and maj-11a was found to be a potent κ-opioid receptor agonist (Ki = 35.13 nM). More importantly, the dose for the sedative effect (ED50 = 9.29 mg kg(-1)) of maj-11a was significantly higher than its analgesic dose (ED50 = 0.392 mg kg(-1)), which made it a promising peripheral analgesic candidate compound with weak sedative side effects.

Determination of sinomenine sustained-release capsules in healthy Chinese volunteers by liquid chromatography-tandem mass spectrometry.

A sensitive and selective liquid chromatographic tandem mass spectrometric method was developed and validated for the determination of sinomenine in human plasma. Plasma samples were precipitated using methanol with metronidazole as internal standard. Separation was carried out on an Inertsil ODS-3 column using a mixture of 0.2% ammonium acetate solution (A) and methanol (B) as the mobile phase with linear gradient elution as follows: 0 min (50%B)→1.5 min (80%B)→4.5 min (80%B)→4.6 min (50%B)→6.0 min (50%B). All mass data were obtained in the positive ion mode, and the fragmentation transitions for the selective multiple reaction monitoring were m/z 330→181 and 172→128 for sinomenine and metronidazole, respectively. The method was fully validated to be accurate and precise with a linear range of 0.5-500 ng/mL and applied to a single- and multiple-dose pharmacokinetics study of sustained-release capsules of sinomenine hydrochloride in 20 healthy Chinese volunteers. After oral administration of a single 60-mg dose, the T(max), C(max), AUC(0-96) and t(1/2) were 7.9±2.0h, 123±22 ng/mL, 3032±682 ng h/mL and 13.4±1.6 h, respectively. After oral administration of the 60 mg capsules twice-daily for 7 consecutive days, these parameters were 4.4±3.6 h, 279±69 ng/mL, 7333±2096 ng h/mL and 15.1±1.3 h, respectively. The AUC and C(max) values after multiple-dose treatment were significantly higher than those after a single-dose treatment (P<0.01), with an accumulation factor of 2.49±0.77.