Characterization and controlled release of gentamicin from novel hydrogels based on Poloxamer 407 and polyacrylic acids

Parenteral administration of gentamicin, a hydrophilic aminoglycoside antibiotic commonlyused in the control of Gram positive and Gram negative infections, is limited by adverse effects such as nephrotoxicity, ototoxicity and neurotoxicity. In this study, topical hydrogels of gentamicin were produced using three polymeric hydrogels of Poloxamer 407 and polyacrlic acids (Carbopols® 971P and 974P), and evaluated  in terms of drug content, pH, swellability in different media, viscosity, spreadability, skin irritation on rats and time-resolved stability. The in vitro permeation of gentamicin from the hydrogel formulations was carried out in phosphate buffered saline using a modified Franz diffusion apparatus. Results obtained indicate that gentamicin-loaded hydrogels showed good encapsulation, stability, pH-dependent swelling, tolerability on rats, greater percentage drug release than the commercially available gentamicin ointment and pure sample of gentamicin. Overall, Poloxamer 407 hydrogels of gentamicin gave the most desirable properties in terms of drug permeation, spreadability, pH, swellability and viscosity, superior to polyacrylic acids hydrogels of gentamicin. This study has shown that Poloxamer 407 hydrogels of gentamicin could offer a promising approach for topical delivery of gentamicin for the treatment of skin infections caused by gentamicin-susceptible bacteria.   Key words: Poloxamer 407 (P407), topical hydrogels, gentamicin, polyacrylic acids (Carbopols® 971P and 974P), antimicrobial activities.