Figure 26. Plot of the cumulative amounts ( yg) of buprenorphine (1) excreted in
urine against the area under the plasma concentration-time curve (AUC ,
yg.min/ml) in accordance with the equation (30):
I U = Cl ( AUC. AUCn )
ren t 0
where AUC^ is the area under the plasma concentration-time curve at E U = 0. For
the 1.4171 rrq/kg IV bolus dose of buprenorphine in dog A, Study #1, the curve
shows three distinctly linear segments attributatble to the pH effect of urine.
The slope (Clren) of the initial linear segment for the pH range between 5.2-5.8
was estimated to be 2.69 ml/min. See also next figure.