Safety of Amikacin Gel for Open Wound Management

In the Literature

Peng ZH, Dickerson VM, Fajt VR, Gould EN, Droog M, Thieman Mankin KM. Serum amikacin concentrations in dogs with naturally occurring open wounds treated with topical amikacin in carboxymethylcellulose hydrogel. Vet Surg. 2024. doi:10.1111/vsu.14195

The Research …

Topical antimicrobial medication can attain supratherapeutic concentrations in open wounds, maximizing antibacterial activity and combating inhibition of wound healing due to biofilm formation.¹ Topical amikacin gel compounded with 3% carboxymethylcellulose has been shown to elute amikacin at concentrations above the minimum inhibitory concentration for biofilm-associated Staphylococcus pseudintermedius in vitro.² Such drug concentrations cannot be achieved via systemic aminoglycoside administration without risk for significant nephrotoxicosis or ototoxicosis.

This study quantified serial serum amikacin concentrations in client-owned dogs (n = 11) following application of topical amikacin (45 mg/mL) compounded in 3% carboxymethylcellulose hydrogel to open wounds. The median number of applications per dog was 2 (range, 1-6). A serum amikacin level higher than the assay’s lower limit of quantification (2.5 micrograms/mL) but lower than the toxicity threshold (5 micrograms/mL) was detected in 5 of 142 serum samples. All samples were collected 1.3 to 110.6 hours after gel application. The 5 samples with detectable quantities of amikacin were collected 1.9 to 2.4 hours after application, and serum levels in these patients decreased below the detection threshold by 4 hours postapplication. Serum amikacin levels did not correlate with the mass or volume of gel used, regardless of the size of the patient or wound area. Only 2 dogs received an amikacin dose >10 mg/kg based on number of gel applications, volume of gel applied, and the dog’s body weight.

… The Takeaways

Key pearls to put into practice:

• Increasing prevalence of multidrug-resistant bacteria and the compromising effects of biofilm formation in infected wounds indicate a need for judicious antimicrobial selection.³ Antimicrobials have been categorized according to both their importance in veterinary medicine and the potential public health consequences of increased antimicrobial resistance.⁴ Aminoglycosides, including amikacin, are in a lower tier than fluroquinolones and should therefore be preferred. In addition, topical application can achieve therapeutic concentrations at the site of infection and minimize exposure of nontarget bacteria at other sites (eg, GI microbiome).

• Amikacin gel may be an additional therapeutic option for superficial surgical site infections and may support reduced reliance on postoperative antimicrobial prophylaxis.

• Patients with serum concentrations that remain above the toxicity threshold for sustained periods have risk for aminoglycoside accumulation in renal proximal tubular cells and subsequent renal tubular toxicosis.⁵ The brief duration of detectable serum amikacin concentrations following topical gel application in this study suggests low risk for nephrotoxicosis.

• Topical amikacin gel may be used safely for open wound management, as serum amikacin levels are unlikely to exceed toxicity thresholds. Adequate wound coverage from local gel application is frequently achieved with doses well below standard systemic doses (15-30 mg/kg); however, caution is warranted if substantial volumes of gel are needed (eg, for large wounds) or the patient has pre-existing renal compromise, as safety in these cases has not been established.