Figure 22. Semi1ogarithmic plots of the amounts of metabolite (M) remaining to be
excreted in urine versus time (sigma minus plot) following IV bolus administration
of buprenorphine (1) in accordance with equation 20. a) The excretion data of M in
urine up to 700 min could be fitted to a simple linear equation in dog A, Study #1
at 1.4171 mg/kg dose of buprenorphine. The excretion rate was estimated to be 330
ng/min. b) Sigma minus plot of M in urine of dog B, Study #2 following 1.6369
mg/kg dose of buprenorphine, resulting in a estimated apparent rate constant
0.0032/min (half-life = 215 min), c) Sigma minus plot of M in urine for the 1.2023
mg/kg dose of buprenorphine in dog C, Study #4. The apparent rate constant was
estimated tas 0.0022/min (half-life = 312 min), d) Sigma minus plot of the urinary
excretion of M for the 2.5632 mg/kg IV bolus dose of buprenorphine in dog B, Study
#3. The da tata were fitted to a sum of two exponentials in accordance with
equation 20. The estimate apparent rate constants were 0.023/min (half-lige = 30
min) and 0.000567/min (half-life = 1220 min) respectively.