The effect of SKF-525A and of altered hepatic blood flow on lidocaine clearance in the cat.

Hepatic blood flow and hepatic uptake of lidocaine were determined in cats during constant intravenous infusion of lidocaine. Lidocaine clearance is directly linked to hepatic blood flow with reductions in flow being reflected in equal reductions in hepatic clearance. Altered blood flow did not result in altered rates of lidocaine extraction. Lidocaine extraction ratio was 28%. Hepatic blood flow and lidocaine metabolism were measured before and 60 min after an intramuscular injection of SKF-525A (50 mg/kg). SKF-525A produced a reduction in hepatic clearance of lidocaine to 60% of control values, entirely as a result of a reduction in hepatic extraction ratios. Hepatic blood flow and vascular conductance were not affected by SKF-525A.