Pharmacokinetics of ropivacaine in patients with chronic renal failure

Abstract

Background: As ropivacaine and its metabolites are excreted by the kidneys, we studied their disposition in subjects with renal dysfunction.

Methods: Twenty patients with moderate or severe renal insufficiency and 10 healthy volunteers received ropivacaine 1 mg kg(-1) i.v. over 30 min. The concentrations of ropivacaine and its main metabolites, pipecoloxylidide (PPX) and 3-hydroxy-ropivacaine, were measured in plasma and urine for 16-48 h. The relationship between pharmacokinetic parameters and creatinine clearance (CL(CR)) was assessed. A model for estimating non-renal clearance of a metabolite of ropivacaine is described.

Results: Renal dysfunction had little or no influence on the pharmacokinetics of ropivacaine. The median plasma concentrations of unbound ropivacaine were similar in uraemic and non-uraemic subjects. Renal clearance of PPX correlated significantly with CL(CR) (R(2)=0.81). Lack of correlation between total PPX exposure, expressed as area under the total plasma concentration-time curve from zero to infinity, and CL(CR) suggests that the clearance of PPX also includes non-renal elimination. However, in two uraemic patients, there was increased exposure to PPX resulting from low non-renal elimination.

Conclusions: The pharmacokinetics of ropivacaine is not affected by renal failure. Although the renal clearance of PPX correlates with CL(CR), non-renal elimination seems to compensate for reduced renal clearance in most patients. PPX may accumulate in plasma during long-term postoperative infusions, in particular in patients with co-existing low non-renal elimination. Systemic toxicity is still unlikely because PPX is markedly less toxic than ropivacaine.