Fabrication, assessment, and optimization of alendronate sodium nanoemulsion-based injectable in-situ gel formulation for management of osteoporosis

Abstract

Low bone mass, degeneration of bone tissue, and disruption of bone microarchitecture are all symptoms of the disease osteoporosis, which can decrease bone strength and increase the risk of fractures. The main objective of the current study was to use a phospholipid-based phase separation in-situ gel (PPSG) in combination with an alendronate sodium nanoemulsion (ALS-NE) to help prevent bone resorption in rats. The effect of factors such as concentrations of the ALS aqueous solution, surfactant Plurol Oleique CC 497, and Maisine CC oil on nanoemulsion characteristics such as stability index and globular size was investigated using an l-optimal coordinate exchange statistical design. Injectable PPSG with the best nanoemulsion formulation was tested for viscosity, gel strength, water absorption, and in-vitro ALS release. ALS retention in the rats' muscles was measured after 30 days. The droplet size and stability index of the optimal nanoemulsion were 90 ± 2.0 nm and 85 ± 1.9%, respectively. When mixed with water, the optimal ALS-NE-loaded PPSG became viscous and achieved 36 seconds of gel strength, which was adequate for an injectable in-situ formulation. In comparison with the ALS solution-loaded in-situ gel, the newly created optimal ALS-NE-loaded PPSG produced the sustained and regulated release of ALS; hence, a higher percentage of ALS remained in rats' muscles after 30 days. PPSG that has been loaded with an ALS-NE may therefore be a more auspicious, productive, and effective platform for osteoporosis treatment than conventional oral forms.

Keywords: In situ gel; PPSG; alendronate sodium; design of experiment; nanoemulsion; osteoporosis.

Figure 1.

Perturbation graph (a), contour plot (b), and 3 D surface plot (c) illustrating the influence of different factors on the droplet size (Y₁) of various ALS-NE formulations.

Figure 2.

Perturbation graph (a), contour plot (b), and 3 D surface plot (c) illustrating the influence of different factors on the stability index (Y₁) of various ALS-NE formulations.

Figure 3.

Desirability ramp and bar chart for optimization process. (a) The desirability ramp illustrated the levels of studied factors and anticipated estimations for dependent variables of the optimized formulation. (b) The bar chart presents the desirability assessments for the collective responses.

Figure 4.

In-vitro release profiles of ALS aqueous solution from optimized ALS-NE–loaded PPSG and control ALS solution containing PPSG (mean ± SD, n = 3).

Figure 5.

The percentage of ALS released in the muscles for various tested groups after 30 days.