Cefadroxil does not alter pharmacokinetics of diclofenac
Clinical evidence,mechanism, importance and management
A pharmacokinetic study in 8 patients who had undergone cholecystectomy and who had a T-drain in common bile duct, found that diclofenac 50mg every 12 hrs increased excretion of intravenous ceftriaxone 2 g in bile by about fourfold and roughly halved urinary excretion (See reference number 2). The clinical importance of this is uncertain,but probably small.
Animal studies have shown that diclofenac may alter pharmacokinetics of some cephalosporins (the AUCs of cefotiam and ceftriaxone were increased by diclofenac, although pharmacokinetics of cefmenoxime were not affected). The significance of these findings in humans is unknown and further studies are required before any valid conclusions can be drawn from this data (See reference number 3).
Schumacher A,Geissler HE, Mutschler E, Osterburg M. Untersuchungen potentieller Interaktionen von Diclofenac-Natrium (Voltaren) mit Antibiotika. Z Rheumatol (1983) 42, 25–7.
Merle-Melet M,Bresler L, Lokiec F, Dopff C, Boissel P, Dureux JB. Effects of diclofenac onceftriaxone pharmacokinetics in humans. Antimicrob Agents Chemother (1992) 36, 2331–3.
Joly V,Pangon B, Brion N, Vallois J-M, Carbon C. Enhancement of the therapeutic effect ofcephalosporins in experimental endocarditis by altering their pharmacokinetics with diclofenac. J Pharmacol Exp Ther (1988) 246, 695–700.