Structural Insights into the Microemulsion‐Mediated Formation of Fluoroquinolone Nanoantibiotics

Abstract

Microemulsions (μEs) are being exploited as a potential route for yielding an extensive range of nanoparticles of different chemical nature, shapes and sizes. Nanodrugs offer new avenues for structuring better “drug delivery systems”. In this study, an oil‐in‐water (o/w) μE formulation comprising N‐butyl acetate/polysorbate 80/ethanol/water was developed for the preparation of nanoparticles of fluoroquinolone antibiotics (FLQ‐NPs). A pseudoternary phase diagram was mapped at constant surfactant/cosurfactant (1:2), revealing improved and high loading of FLQs in an optimum μE formulation. The as‐formulated μE showed high loading of FLQs as; levofloxacin (4.20 wt.%), ciprofloxacin (3.16 wt.%), moxifloxacin (2.53 wt.%), gatifloxacin (1.36 wt.%), ofloxacin (0.70 wt.%). Fourier transform IR analysis indicated good compatibility of each FLQ drug with μE excipients. However, dynamic light scattering showed an increase in the average particle size of the μE on drug loading, indicating the accumulation of FLQ at interface layer of the micelle. Additionally, lyophilized levofloxacin (a selected antibiotic) showed long‐term stability, amorphous morphology and improved dissolution rate, inspected by scanning transmission electron microscopy, X‐ray diffraction and electronic spectroscopy, respectively. Moreover, fluorescence measurements suggested the interfacial vicinity of levofloxacin within the μE domain, which may support controlled release of drug during systemic circulation.

Formation of Antihyperlipidemic Nano-Ezetimibe from Volatile Microemulsion Template for Enhanced Dissolution Profile

“…As shown in Figure A, the particle size and PDI value of the EZM-free μE are 28.21 ± 2.31 nm and 0.242, respectively. After loading EZM into the formulation, it was further noted that the particle size and PDI value increased by 43.82 ± 2.52 and 0.324, respectively, which indicates the accumulation of EZM at the droplet interface, confirmed by past studies. − ,− In addition, each formulation showed a low PDI value and solitary size distribution peak, suggesting the unimodal distribution of nanodroplets. ,,, The outcomes are presented in Table .…”

“…Fortunately, with the help of the ζ-potential value, the colloidal stability of the droplets can be demonstrated. The literature shows that because of electrostatic repulsion between nanoparticles, the highly stable μE droplets have a ζ-potential value of >30 or <−30 mV. ,,,− In this research, the ζ-potential of the EZM-free μE was −32.5 ± 1.4 mV, indicating the high stability of the μE. In contrast, a slightly higher negative ζ-potential (−38.7 ± 1.9 mV) of the EZM-loaded μE indicates its high stability.…”

“…Physical conformation of EZM-NPs and EZM-bulkpowder was measured by powder XRD. ,,, XRD (Bruker, D2-Phaser) measurement was carried out in the 10–70 range of 2θ (degree) with 0.02° variation with a scan rate of 4°/min. The sample weight was about 0.5 g. The diffraction grating of the EZM-bulkpowder was co-related with that of its nanodispersion.…”

“…To address the above concerns, numerous formulation strategies such as micelles, emulsions, microemulsions (μEs), vesicles, liposomes, polymer conjugates, polymersomes, nanoparticles, microspheres and nanospheres, lipid carriers, use of prodrugs, drug derivatization, solution phase studies, and penetration enhancers have been used to enhance the drug dissolution rate and bioavailability. − However, owing to the structural flexibility and stability, the use of template μEs can produce nanometer-sized functional APIs of different sizes, shapes, and chemical properties with minimal agglomeration. − The formation of highly wettable functional organic nanopowders through volatile μE templates has many advantages over commonly used methods, such as low cost, simple preparation, low energy investment, and potential for scale expansion into multidose formulations. In addition, the resulting nanopowder is expected to have a high chemical and microbial stability and extended shelf-life. − ,− …”

Microemulsified Gel Formulations for Topical Delivery of Clotrimazole: Structural and In Vitro Evaluation

“…Enhanced delivery of lipophilic, hydrophilic, and amphiphilic drugs can be achieved through μE formulation. − The main advantages of μE formulations are considered to be the ingestion of a large amount and an enormous increase in the solubilization of the drug. The μE formulation also plays a critical role in the stability and absence of aggregation of the drug, which further corresponds to the steady-state release of the drug. − …”