Long-term stability of gentamicin sulfate-ethylenediaminetetraacetic acid disodium salt (EDTA-Na2) solution for catheter locks

A lock solution composed of gentamicin sulfate (5 mg/mL) and ethylenediaminetetraacetic acid disodium salt (EDTA-Na2, 30 mg/mL) could fully eradicate in vivo bacterial biofilms in totally implantable venous access ports (TIVAP). In this study, fabrication, conditioning and sterilization processes of antimicrobial lock solution (ALS) were detailed and completed by a stability study. Stability of ALS was conducted for 12 months in vial (25 °C ± 2 °C, 60% ± 5% relative humidity (RH), and at 40 °C ± 2 °C, RH 75% ± 5%) and for 24 h and 72 h in TIVAP (40 °C ± 2 °C, RH 75% ± 5%). A stability indicating HPLC assay with UV detection for simultaneous quantification of gentamicin sulfate and EDTA-Na2 was developed. ALS was assayed by ion-pairing high performance liquid chromatography (HPLC) needing gentamicin derivatization, EDTA-Na2 metallocomplexation of samples and gradient mobile phase. HPLC methods to separate four gentamicin components and EDTA-Na2 were validated. Efficiency of sterility procedure and conditioning of ALS was confirmed by bacterial endotoxins and sterility tests. Physicochemical stability of ALS was determined by visual inspection, osmolality, pH, and sub-visible particle counting. Results confirmed that the stability of ALS in vials was maintained for 12 months and 24 h and 72 h in TIVAP.