Investigation of a Minocycline-Loaded Nanoemulgel for the Treatment of Acne Rosacea

Abstract

In the present investigation, a nanoemulgel of minocycline was formulated and optimized for an improved drug delivery and longer retention time in the targeted area. Combining eucalyptus oil, Tween 20, and Transcutol HP, different o/w nanoemulsions were formulated by the oil phase titration method and optimized by pseudo-ternary phase diagrams. The morphology, droplet size, viscosity, and refractive index of the thermodynamically stable nanoemulsion were determined. Furthermore, optimized nanoemulsion was suspended in 1.0% w/v of Carbopol 940 gel to formulate the nanoemulgel, and for this, pH, viscosity, and spreadability were determined and texture analysis was performed. To compare the extent of drug penetration between nanoemulsion and nanoemulgel, ex vivo skin permeation studies were conducted with Franz diffusion cell using rat skin as the permeation membrane, and the nanoemulgel exhibited sustained-release behavior. It can be concluded that the suggested minocycline-containing naoemulgel is expected to treat acne rosacea more effectively.

Keywords: Carbopol 940; eucalyptus oil; minocycline; o/w nanoemulsion; permeation study.

Figure 1

Pseudo-ternary phase diagrams showing different Smix ratios of the surfactant/cosurfactant ratio, (a) 1:1; (b) 1:2; (c) 2:1; (d) 4:1; (e) 5:1, of the nanoemulsion, which is composed of Tween 20 (surfactant), Transcutol HP (cosurfactant), eucalyptus oil as oil phase, and water (q.s).

Figure 2

Zeta potential graph of optimized formulation.

Figure 3

Differential scanning calorimetry (DSC) thermogram of (a) minocycline nanoemulgel (NEG) and (b) pure minocycline.

Figure 4

TEM image of nanoemulsion.

Figure 5

Release profile of minocycline nanoemulsion (NE) and minocycline nanoemulgel (NEG).

Figure 6

Permeation profile of minocycline nanoemulsion (NE) and minocycline nanoemulgel (NEG).

Figure 7

Confocal laser scanning microscopy (CLSM) images showing the penetration and distribution of the formulation at (a) 0, (b) 5, (c) 10, (d) 15, (e) 20, and (f) 25 µm.