Saliva and plasma clearance of antipyrine as reflectors of liver function.

Antipyrine kinetics, after oral administration to patients with changes in liver function were determined from data obtained by measuring drug concentration in saliva and plasma. Antipyrine kinetics calculated from saliva concentrations did not diverge from values obtained from plasma antipyrine measurements. The saliva and plasma clearance rates were reduced in parallel in subjects with liver parenchymal disease, and showed similar increases in subjects with normal liver treated with enzyme inducing drugs as compared to values in subjects with normal liver and no inducing treatment. The clearance values were related to changes in liver histology. The area under the concentration/time curve was increased in subjects with altered liver histology, and reduced in subjects with normal liver and therapy with enzyme inducing drugs. Antipyrine saliva clearance seems to be a useful method for assessing hepatic drug metabolism and liver microsomal function in vivo in subjects with varying degrees of liver function damage.