Poly(Ethylene Glycol)-block-Poly(ε-Caprolactone) Nanomicelles for the Solubilization and Enhancement of Antifungal Activity of Sertaconazole

Sertaconazole nitrate is a broad spectrum imidazole antifungal agent with antibacterial and anti-inflammatory properties. However, its lipophilic nature and very poor aqueous solubility limit its use in the clinic. The aim of this study was to develop and characterize poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL) polymeric nanomicelles for the solubilization and enhancement of sertaconazole antifungal activity. Sertaconazole was incorporated into PEG-b- PCL polymeric nanomicelles by a co-solvent evaporation method and micelle size, drug loading capacity and drug release properties were determined. The antifungal properties of nanomicelle-loaded drug were evaluated in Fusarium miscanthi, Microsporum canis, and Trichophyton mentagrophytes isolated, respectively from fungal keratitis, ringworm, and tinea corporis. PEG-b-PCL formed nanomicelles in aqueous solution with a diameter ranging from 40-80 nm, depending on the polymer composition and level of drug loading. Drug loading properties of the nanomicelles were dependent on the PCL block molecular weight and drug/polymer weight feed ratio. Drug encapsulation efficiency of up to 85% was achieved and this resulted in more than 80-fold enhancement in sertaconazole aqueous solubility at polymer concentration of 0.2%. Drug release studies showed an initial burst release followed by sustained drug release for 72 hours. In vitro antimycotic studies showed that nanomicelle-incorporated sertaconazole inhibited fungal growth in a concentration dependent manner. Further, it was more effective than the free drug in inhibiting the growth of Fusarium miscanthi and Microsporum canis. These results confirm the utility of PEG-b-PCL nanomicelles in enhancing the aqueous solubility and antifungal activity of sertaconazole or other similar antifungal drugs.