Association of Borage Oil and Betamethasone Dipropionate in Lipid-Core Nanocapsules: Characterization, Photostability and In Vitro Irritation Test.

The association of vegetable products to nanostructured systems has attracted the attention of researchers due to several advantages, such as drug photoprotection, as well as the improvement of the pharmacological and therapeutic activities because of synergistic action, which can provide their topical application. In this work, lipid-core nanocapsules containing borage oil as oil core and betamethasone dipropionate were developed, and nanocapsules without the drug were prepared for comparison. The suspensions were characterized in relation to mean particle size, zeta potential, pH, drug content, and encapsulation efficiency. A photodegradation study was carried out and the in vitro release profile as well as the irritation potential of the drug after nanoencapsulation were also evaluated. In addition, the antiproliferative activity of the free borage oil as well as loaded in nanocapsules was studied. Lipid-core nanocapsules showed nanometric mean size (185-210 nm); polydispersity index below 0.10; negative zeta potential and pH slightly acid (6.0-6.2). Moreover, the drug content was close to theoretical concentration (0.50 +/- 0.03 mg/ml of betamethasone), and the encapsulation efficiency was approximately 100%. The study of the antiproliferative activity of borage oil showed ability to reduce cell growth of Allium cepa. The nanoencapsulation of betamethasone dipropionate provided greater protection against UVC light and decreased the irritation potential of the drug. The release profile of betamethasone dipropionate from nanocapsules followed monoexponential model.