Pharmacokinetics of 6beta-naltrexol after single and multiple intramuscular injections in Beagle dogs / 药学学报

The pharmacokinetics of 6beta-naltrexol (6beta-NOL) following single intramuscular administration and multiple intramuscular injection once per day for seven days was studied in 4 Beagle dogs. Plasma concentration of 6beta-NOL in dogs was analyzed by a combination of high performance liquid chromatography (HPLC) and electrochemical detection with naloxone (NLX) as internal standard. After single intramuscular injection of 0.2 mg x kg(-1) 6beta-NOL, the plasma concentration-time curve of the drug was found to fit to a two compartment model with first-order absorption. The main parameters of single dosing were as follows: t1/2alpha was (0.26 +/- 0.23) h, t1/2beta was (4.77 +/- 1.65) h, C(max) was (81.65 +/- 5.61) ng x mL(-1), t(peak) was (0.27 +/- 0.07) h, CL(s) was (1.20 +/- 0.06) L x kg(-1) x h(-1), V/F(c) was (1.94 +/- 0.15) L x kg(-1), and AUC(0-t) was (166.82 +/- 7.68) ng x h x mL(-1), separately. After multiple intramuscular injection of 0.2 mg x kg(-1) 6beta-NOL once per day for seven days, the plasma concentration-time curve of the drug fitted to a two compartment model with first-order absorption too. The main parameters of the last dosing were as follows: t1/2alpha was (0.19 +/- 0.18) h, t1/2beta was (5.79 +/- 1.50) h, C(max) was (79.82 +/- 10.5) ng x mL(-1), t(peak) was (0.18 +/- 0.08) h, CL(s) was (1.12 +/- 0.07) L x kg(-1) x h(-1), V/F(c) was (2.10 +/- 0.27) L x kg(-1), and AUC(0-t) was (173.23 +/- 9.49) ng x h x mL(-1), separately. The difference of the parameters between the first and the last dosing was not significant, showing that the plasma kinetics of 6beta-naltrexol was not changed after multiple administrations. In the course of multiple administration, the peak and valley concentration of plasma 6beta-naltrexol were (79.03 +/- 10.3) and (1.50 +/- 0.93) ng x mL(-1), respectively. No clear adverse events were noted during this study. These results showed that plasma 6beta-naltrexol fits to a two compartment model with first-order absorption in dog after intramuscular administration and their pharmacokinetic parameters were reported. There was no remarkable change on plasma pharmacokinetics of 6beta-naltrexol after multiple intramuscular administrations.

Structure-activity relationships analysis of thienorphine and its derivatives / 药学学报

Thienorphine is a chemically-new opioid developed in Beijing Institute of Pharmacology and Toxicology. To elucidate the chemical basis for the unique pharmacological effects of thienorphine, 15 derivatives were synthesized according to combinatorial chemistry and the structure-activity relationships of these compounds were studied. It is demonstrated that thienorphine is a potent long-acting partial agonist. N-Cyclopropylmethyl is responsible for the antagonist effect of thienorphine. More importantly, thiophene at the end of side chain is most likely the pharmacophore accounts for the long-lasting effect of thienorphine. Change of the connection of thiophene and the side chain does not result in changes in the antinociceptive activity.