Terpene-enhanced olaminogel for superior vaginal permeation: robust assessment through in vitro, microbiological, ex vivo, and in vivo evaluations

Abstract

Abstract Vulvovaginal fungal infections remain a major therapeutic challenge due to poor drug penetration, recurrence, and limited efficacy of conventional formulations. Harnessing nanotechnology with a novel delivery platform offers a promising strategy to overcome these barriers. In this study, an innovative olaminogel was designed as an advanced nanocarrier for terconazole (TCZ) to enhance local antifungal therapy via the vaginal route. The formulation was prepared using the ethanol injection method and systematically optimized through a 2 3 factorial design considering limonene-to-surfactant ratio (factor A), oleylamine-to-drug ratio (factor B), and oleic acid-to-surfactant ratio (factor C). Optimization targeted maximal entrapment efficiency (EE%), minimal particle size (PS), and stable zeta potential (ZP). The optimized olaminogel achieved an EE% of 82.11, nano-metric PS of 217.25 nm, and a ZP of − 33.05 mV. TEM confirmed well-formed vesicles, while FTIR verified successful encapsulation. Further in vitro characterization revealed pseudo-plastic rheology, sustained biphasic drug release, and stability for 3 months. Mucoadhesion testing demonstrated strong adhesion of the olaminogel to vaginal mucosa. Ex vivo permeation across rabbit vaginal mucosa demonstrated significantly deeper penetration (180 µm vs. 55 µm) compared with plain TCZ gel, corroborated by in vivo CLSM imaging. Histopathological studies further confirmed biocompatibility and absence of irritation. Importantly, microbiological evaluation revealed markedly reduced MIC and MFC values, alongside an accelerated fungicidal effect, outperforming TCZ control. Collectively, these findings highlight olaminogel as a novel and potent intravaginal nanocarrier capable of improving drug retention, mucosal penetration, and antifungal efficacy, thereby presenting a next-generation platform for safe and effective management of vaginal fungal infections. Graphical Abstract