Population pharmacokinetic and pharmacodynamic analyses of teicoplanin in Japanese patients with systemic MRSA infection

Teicoplanin is a glycopeptide antibiotic used for the treatment of MRSA infection. An initial loading dose of 400 mg every 12 hours for three doses is the standard dosing regimen. This study aimed to assess whether this regimen was appropriate based on the pharmacokinetic/pharmacodynamic (PK/PD) analyses in Japanese patients.We conducted a population pharmacokinetic (PPK) analysis of teicoplanin by NONMEM using serum drug concentrations obtained from 116 patients with MRSA infection. PD of the drug was analyzed by a model assuming that the variability of therapeutic responses (assessed by body temperature, serum C-reactive protein concentrations, and white blood cell counts) on the 3rd, 7th or 14th day of treatment is associated with the logarithm of serum unbound drug concentration (Cmax,unbound) divided by the MIC against MRSA (log[Cmax,unbound/MIC]).The final PPK model showed that creatinine clearance and serum albumin concentration were significant (p < 0.01) covariates of systemic clearance and peripheral volume of distribution of teicoplanin, respectively. The PD analyses indicated that log[Cmax,unbound/MIC] of 0.30 on Day 3 of teicoplanin therapy was the threshold for achieving successful clinical responses. Integrating the PK and PD data, we consider that the standard loading dose regimen would attain the threshold serum level within the initial 3 days in only less than 50% of the patients.We propose that an extended loading regimen (400 mg every 12 hours for the first 5 doses) would be a treatment option to maximize the therapeutic effects of teicoplanin in patients with systemic MRSA infection.