Meropenam: Dosing in Obesity

Pharmacokinetic

• time dependent activity
• tend to have higher volume of distribution and clearance, which may cause lower meropenam levels
• however, meropenem pharmacokinetics are similar between obese and non-obese patients, so same dosages provide comparable pharmacodynamic exposures for susceptible organisms between obese and non-obese patients

Effectiveness

• routine dose escalation not recommended as standard dosing regimen able to achieve adequate PD exposure for susceptible pathogen (MIC <2mg/ml)
• only the dosing 2g TDS and 1g QID was able to achieve MIC > 4mg/ml
• prolonging the infusion time to 3h enhanced the dosage regimen 

Alternative Dosings

• similar clinical outcomes seen between traditional (1g TDS) and alternative meropenem dosing (500mg QID) strategies in previous studies may extend to obese patients

Conclusion

• dose escalation not recommended as standard dosing regimen able to achieve adequate PD exposure
• however doses can be increased if higher MIC is required, exm multi resistant p.aeruginosa. 

References:

1. http://formularyjournal.modernmedicine.com/formulary-journal/content/tags/antibiotics/underdosing-obesity-epidemic-focus-antibiotics
2. Drug Dosing in Obesity: Volume I: Antimicrobials. 
3. https://idsa.confex.com/idsa/2015/webprogram/Paper51176.html
4. http://docs.lib.purdue.edu/dissertations/AAI3719044/
5. http://pusware.com/testpus/drug_Obesity_dosing.html
6. UKCPA: Drug Dosing in Extremes of Body Weight in critically ill patients. 1st Edition (v1.0)September 2013