Pharmacokinetic study of the digoxin-acenocoumarol interaction in rabbits.
A study was carried out to evaluate the potential pharmacokinetic interaction between digoxin and acenocoumarol. The binding of digoxin to rabbit cardiac tissue homogenates was assessed in vitro, using the equilibrium dialysis technique. An increase in the first-order constant (p<0.05) and a reduction in the partition coefficient in the equilibrium situation (p<0.001) of digoxin were observed when the cardiac homogenates were previously treated with acenocoumarol. In the in vivo study, the kinetics of digoxin administered in single and multiple dosage regimens were compared in control rabbits and in rabbits treated simultaneously with acenocoumarol. Kinetic analysis of the results was performed using Non-linear Mixed Effects Modeling (NONMEM). In the presence of acenocoumarol, the population distribution volume (Vd) of digoxin was increased by 40-60%, no differences being found as regards the elimination clearance. Also, joint administration of both drugs led to a reduction in digoxin concentrations in the heart (p<0.01) at the end of the dosage regimen. Both sets of results point to the hypothesis of a hitherto unreported possible pharmacokinetic interaction between the two drugs affecting the distribution process. This interaction could lead to lower plasma digoxin levels, in view of the increased Vd, and a possible reduction in the therapeutic effect, owing to the decrease in affinity and in concentration in heart tissue.
Martin-Suarez
Ana
A
Department of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, University of Salamanca, Campus Unamuno, 37007 Salamanca, Spain.
Atencio
Drury Rudolph
DR
Lopez
Francisco González
FG
Santos
María
M
Zarzuelo
Aránzazu
A
Mendez
María Eugenia
ME
Alberca
Ignacio
I
Lanao
José Martínez
JM
D000074:Acenocoumarol / Q000008:administration & dosage / Q000378:metabolism / Q000493:pharmacokinetics*; D000818:Animals; D001667:Binding, Competitive; D004077:Digoxin / Q000008:administration & dosage / Q000378:metabolism / Q000493:pharmacokinetics*; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D066298:In Vitro Techniques; D007275:Injections, Intravenous; D007279:Injections, Subcutaneous; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D017711:Nonlinear Dynamics; D011817:Rabbits; D014018:Tissue Distribution
D004077:Digoxin; D000074:Acenocoumarol