RT Journal Article
SR Electronic
T1 Pharmacokinetic analysis of enterohepatic circulation of buprenorphine and its active metabolite, norbuprenorphine, in rats.
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 2
OP 7
VO 22
IS 1
A1 M Ohtani
A1 H Kotaki
A1 K Uchino
A1 Y Sawada
A1 T Iga
YR 1994
UL http://dmd.aspetjournals.org/content/22/1/2.abstract
AB The pharmacokinetic characteristics of buprenorphine (BN) and its active metabolite, norbuprenorphine (NBN), was investigated using rats. The elimination half-life (t1/2), total body clearance (CLtot), and steady-state volume of distribution (Vdss) of BN (0.6 mg/kg iv dose) in the intact rat were 2.8 hr, 23.3 ml/min/kg, and 4.2 liters/kg, respectively, and those of NBN (0.6 mg/kg iv dose) were 0.9 hr, 35.0 ml/min/kg, and 2.0 liters/kg. Within 24 hr after administration of BN (0.6 mg/kg dose) to the bile-fistula rat, 74.1% of dose was excreted in the bile as BN glucuronide (BN-Glu) and 18.5% as NBN glucuronide (NBN-Glu), and in urine < 3.2% as BN-Glu. After administration of NBN to the bile-fistula rat, 85.1% and 9.1% of the dose were excreted as NGN-Glu in bile and urine, respectively. The existence of the enterohepatic circulation (EHC) of BN and NBN was confirmed by using paired rats: the donor and recipient rats. Within 24 hr after administration of BN (0.6 mg/kg dose) to the donor rat, 58.8% of the dose was reexcreted as NBN-Glu in bile of the recipient and 25.1% as BN-Glu. Based on the results of in vitro metabolism, it was suggested that this increase in the proportion of NBN-Glu in bile observed after one enterohepatic cycling of BN may be due to the first-pass metabolism in the liver. BN was detected in the plasma of the recipient rat after administration of BN, to the donor rat.(ABSTRACT TRUNCATED AT 250 WORDS)