TY - JOUR T1 - In vitro digitoxin metabolism. Rate-limiting step and alteration following spironolactone pretreatment. JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 635 LP - 639 VL - 13 IS - 6 AU - W C Kershaw AU - P Campbell AU - G L Lage Y1 - 1985/11/01 UR - http://dmd.aspetjournals.org/content/13/6/635.abstract N2 - The biotransformation of digitoxin was considered as a linear transformation comprised of dual deoxy sugar cleavages culminating with product conjugation to glucuronic acid. Digitoxin and two metabolites, digitoxigenin bisdigitoxoside and digitoxigenin monodigitoxoside, were each incubated for 1 hr with rat liver slices. Measurements of amounts of various metabolites allowed determination of rate constants, showing the cleavage of the terminal sugar from digitoxigenin bisdigitoxoside to be the rate-limiting step. The inductive action of spironolactone predominately affected the rate-limiting step. ER -