Pharmacokinetics of cefoxitin in patients with normal or impaired renal function

Summary

The pharmacokinetics of cefoxitin have been determined after a single i.v. injection of 15 mg/kg body weight in 10 patients with normal renal function and 20 patients with varying degrees of renal impairment. The kinetics of the antibiotic followed an open two-compartment model. In patients with normal renal function the following pharmacokinetic parameters were found:

$$\begin{gathered} \begin{array}{*{20}c} {\alpha = 8.66 h^{ - 1} } & {\beta = 1.21 h^{ - 1} } & {K_{12} = 3.47 h^{ - 1} } \\ \end{array} \hfill \\ \begin{array}{*{20}c} {K_{21} = 3.17 h^{ - 1} } & {K_{13} = 3.15 h^{ - 1} } & {V_c = 4.24 l.} \\ \end{array} \hfill \\ \begin{array}{*{20}c} {V_p = 4.87 l.} & { Vd_{ss} = 9.11 l.} \\ \end{array} \hfill \\ \end{gathered}$$

In the patients with renal impairment there was a significant decrease in$\mathop \alpha \limits_, \mathop \beta \limits_,$ K₁₂, K₂₁ and K₁₃, and an increase in the apparent volume of distribution. The degree of plasma protein binding in patients with normal renal function was 73.6% and this was diminished in patients with renal impairment. A linear relationship between K₁₃ of cefoxitin and creatinine clearance was demonstrated. The dosage regimen for patients with renal impairment should be adjusted by modifying the dosage interval whilst maintaining the amount administered.