Development and characterization of a transdermal patch and an emulgel containing kanamycin intended to be used in the treatment of mycetoma caused by Actinomadura madurae

Background: Mycetoma is a chronic, degenerative, and incapacitating infection of the skin and subcutaneous tissue. Aim: This study focuses on developing a kanamycin-based auxiliary system intended to be used in the treatment of mycetoma caused by Actinomadura madurae. Methods: Transdermal patches (with two different formulations: one with free kanamycin [K] and the other one with kanamycin adsorbed in silica [K-SG]) and an emulgel were developed. Both patches were prepared by the casting-evaporation technique. To characterize them, differential scanning calorimetry, bioadhesion, post-moisture detachment, strength and rupture distance, gas exchange, water uptake, and dissolution studies were carried out. The emulgel (containing 0.57% of kanamycin) was prepared from an oil-in-water emulsion, which was then incorporated to a gel. Results: the patches with the best characteristics contained 22.9% of silica and 14.6% of kanamycin. Dissolution studies indicated that 8.8% of kanamycin released from K and 3.2% from K-SG at 24h. The emulgel containing 0.57% of kanamycin showed good technological characteristics for its application to the skin (viscosity, 44.9 +/- 1.4 poises; pH, 6.9 +/- 0.4; and penetrability, 52.7 +/- 5.1). Conclusions: The optimal patches were those containing 15.9% of freely dispersed kanamycin (K) and 14.6% of kanamycin adsorbed in silica (K-SG), which corresponds to the batch 2-0.8. The assessments performed to both pharmaceutical forms (patches and emulgel) show that they have the adequate technological characteristics for being used as an auxiliary in the treatment of actinomycetoma caused by A. madurae.