DRUG PRESCRIPTION IN RENAL-IMPAIRED DOGS

Prescription of a drug in a dog with concomitant renal impairment is a n up-re-date challenge in veterinary medicine because of the high inci dence of renal dysfunction and the lack of adequate laboratory methods for an early detection of renal failure. The kidney plays a major rol e in drug disposition by filtration, secretion, reabsorption and metab olism. For drugs highly eliminated by renal route, any renal dysfuncti on will delay elimination and therefore induce abnormally high plasma levels and increase the risk of adverse reactions. Other consequences of renal failure on drug disposition which have been described in the literature include alteration of drug absorption from the gastrointest inal tract, distribution of drugs in peripheral compartments, and live r metabolism. The sensitivity of the impaired kidney to drug-induced n ephrotoxicity is increased. Therefore, the dosage regimen of many drug s, especially of drugs eliminated mainly in urine, should be adjusted in patients with renal failure. All strategies for dosage regimen adju stment require an adequate preliminary evaluation of renal function wh ich is neither accurate nor precise with the usual plasma markers (cre atinine, blood urea nitrogen) and should be based on correct measureme nt bf the glomerular filtration rate (e.g. determination of creatine c learance). Few data are available on drug disposition in the renal-imp aired don, but basic rules based on good knowledge of the pharmacokine tics, pharmacodynamics and toxicity of the drugs currently employed in canine medicine can help the practitioner prescribe suitable drugs in dogs with concomitant renal failure.