Background and Importance Meropenem is a carbapenemic antibiotic that is mainly eliminated by renal route. Therefore, an alteration of the glomerular filtration rate (GFR) may affect the elimination of the drug. GFR can be calculated using several validated formulas using different parameters.

Aim and Objectives The aim of the study was to analyse the discrepancies between the results of the different GFR equations and the dosage adjustment.

Material and Methods A descriptive, retrospective and cross-sectional study that included patients treated with meropenem for 3 months was performed. The standard dose was 1g every 8 hours. Dose adjustments were made according to a data sheet (TFG <50mL/min and <25mL/min).

Age, sex, weight, creatinine (mg/dl), urea (mg/dl), albumin (g/dl)) and meropenem doses were recorded. With these data, the GFR was calculated: Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) (ml/min/1.73m2); Modification of Diet in Renal Disease Study Equation (MDRD) (ml/min/1.73m2); and Cockcroft-Gault (CG) (ml/min).

Results A total of 136 patients were included. The mean age was 76.84 + 12.7 years. The calculation of mean GFR according to the different equations was as follows: 60.46 ± 49.0 ml/min/1.73m2 (MDRD); 72.12 ± 49.6 ml/min (Cockroft-Gault) and 86.17 ± 63.1 ml/min/1.73m2 (CKD-EPI).

Dose adjustment was carried out In 19.12% (26) of the patients meropenem dose adjustment was performed with GFR <50ml/min and in 12.5% (17) GFR <25ml/min was adjusted.

The dose adjustment of meropenem should have been with MDRD: 39.8% (54) of the patients had a GFR lower than 50ml/min and 23.53% (32) had a GFR lower than 25ml/min. According to Cockroft-Gault: 38.23% (52) of the patients had GFR <50ml/min and 16.17% (22) had GFR <25ml/min. Finally, according to CKD-EPI, 36.03% (49) had GFR <51ml/min and 12.5% (17) had GFR <25ml/min.

Finally, it was observed that 2.2% (3) of the patients had no dose adjustment for GFR <50ml/min when any of the equations indicated this; and that in 14.0% (19), dose adjustment by GFR <25ml/min was not performed when required it.

Conclusion and Relevance There are significant discrepancies in the calculation of GFR with different equations, which affects the dose adjustment of meropenem. Taking into account the values of several equations would improve both the efficacy and safety of meropenem treatment.

Conflict of Interest No conflict of interest.