Abstract Eugenol is a phenolic compound with numerous biological activities. It is widely used in dentistry to treat toothache and pulpitis. In particular, eugenol may be used for tooth whitening procedures to minimize dental sensitivity in patients. However, eugenol has some disadvantages such as its volatility, its photosensitivity, and immediate effect, which can be avoided by using pharmaceutical nanotechnology. The aim of the present study was to obtain, characterize, quantify, and evaluate the physicochemical stability of eugenol-loaded Eudragit RS100 nanocapsules. The nanocapsules (NCs) were prepared by interfacial deposition of the preformed polymer method. The NCs were characterized through morphological and spectroscopic studies. The encapsulation efficiency was achieved by quantifying the non-encapsulated eugenol using a previously developed and validated analytical method. The physicochemical stability of NCs was assessed at predetermined time intervals for 90 days after preparation. The nanocapsules were successfully prepared by the chosen method and had a predominantly spherical shape with a smooth surface. The mean size, the polydispersion index, and the zeta potential were in agreement to literature data. Infrared spectra ensured that the nanoencapsulation process did not result in chemical reactions between the drug and the polymer. The formulations showed encapsulation efficiency higher than 90% and remained stable after 60 days of preparation. Thus, eugenol-loaded Eudragit RS100 nanocapsules may be further considered as an alternative formulation for dental sensitivity in order to provide a controlled release, a decreased toxicity, and a better dental sensitivity relief.

Abstract Hydroxytyrosol (HT) is a natural phenolic compound found in leaves of olive trees. It is a photosensitive solid phytochemical constituent and an irritant substance to skin and mucosa as pure drug. HT is a lipophilic chemical constituent and shows low solubility in water, bitter taste, and instability to oxidizing atmosphere. Considering the limitations for its suitable therapeutic use, the aim of the present study was to obtain, to characterize, to quantify, and to evaluate the stability of HT-loaded poly(ԑ-caprolactone) nanocapsules for its further use in pharmaceutical and nutraceutical products. Nanocapsules were prepared by method of interfacial deposition of the preformed polymer. The formulations were characterized by morphological and spectroscopic methods. The UHPLC-PDA analytical method was developed and validated for quantifying the HT encapsulation. Physicochemical stability assay was performed for 120 days. Nanocapsules were successfully obtained by the proposed method. The morphological evaluation demonstrated the drug absence in the nanocapsule surface. Fourier-transform infrared spectroscopy demonstrated the drug nanoencapsulation. The analytical method was validated and confirmed a high HT encapsulation efficiency over 95%. Considering the physicochemical stability testing, the polydispersity index changed after 30 days for NC-2 (HT at 2 mg/mL) and after 90 days for NC-5 (HT at 5 mg/mL). Zeta potential changed after 60 days for both formulations (NC-2 and NC-5). pH values were modified after 60 days for NC-5 and after 90 days for NC-2. HT-loaded PCL nanocapsules demonstrate adequate physicochemical features and high drug encapsulation. The different formulations revealed stability changes from 30 to 90 days. Additional in vitro and in vivo evaluations may be performed in order to use these nanoformulations for treating several diseases based on oxidative-inflammatory environments.