A novel liposomal formulation for ocular delivery of caspofungin: an experimental study by quality by design-based approach

Abstract

Aim: This study focuses on the development of a Caspofungin liposome for efficient ocular delivery by enhancing corneal penetration.Method: Quality by design (QbD) approach was adopted to identify critical factors that influence final liposomal formulation. The liposome developed using thin film hydration after optimization was subjected to characterization for physicochemical properties, irritation potential and corneal uptake.Results: The numerical optimization suggests an optimal formulation with a desirability value of 0.706, using CQAs as optimization goals with 95% prediction intervals. The optimized formulation showed no signs of irritation potential along with observation of significant corneal permeation.Conclusion: The liposomal formulation increased the permeability of Caspofungin, which could enhance the efficacy for the treatment of conditions, like fungal keratitis.

Keywords: Caspofungin; echinocandins; fungal keratitis; liposome; ocular delivery; quality by design.

Graphical abstract

Figure 1.

Response surface plots generated using box-behnken design to indicate the impact of independent factors on %Encapsulation efficiency (%EE) (A), %drug release at 2 h (Q₂) (B), %drug release at 8 h (Q₈) (C), time required to release 90% of drug (t₉₀) (D), vesicle size (E) and Polydispersity index (PDI) (F).

Figure 2.

Morphological Studies of the Csp-liposomes. (A) Transmission electron microscopic (TEM) image of Csp-liposome particles (Scale = 200 nm); (B) Transmission Electron Microscopic (TEM) image with magnified view of liposomes (Scale = 100 nm); (C) Scanning Electron Microscopic (SEM) photographs of Csp-liposomes (Scale = 200 nm; Average size <100 nm).

Figure 3.

In vitro drug release of liposomal formulation. Data are presented as Mean ± SD (n = 3).

Figure 4.

Ocular irritation study of Csp-liposome. (A) Vascular responses of Chorioallantoic Membrane (CAM) surface treated with 0.9% NaCl, 1%SDS, 0.1N NaOH and Optimized Caspofungin (Csp)-liposome formulation. (B) Cumulative Irritation score in Hen's Egg Chorioallantoic Membrane Test (HET-CAM) test. Results are expressed as mean ± SD, n = 3.

Figure 5.

Ex vivo transcorneal permeation of Csp-liposome. (A) Ex vivo transcorneal permeation of optimized Caspofungin (Csp)-liposomes and Caspofungin (Csp) solution in STF (pH 7.4) at 37°C. Confocal laser scanning microscopy (CLSM) images of (B) Liposome bright field, (C) detection of fluoroscein isothiacyanate (FITC) labeled liposome.