Sarheed, Omar, Shouqair, Douha, Ramesh, KVRNS, Khaleel, Taha, Amin, Muhammad, Boateng, Joshua ORCID: https://orcid.org/0000-0002-6310-729X and Drechsler, Markus (2019) Formation of stable nanoemulsions by ultrasound-assisted two-step emulsification process for topical drug delivery: effect of oil phase composition and surfactant concentration and loratadine as ripening inhibitor. International Journal of Pharmaceutics, 576:118952. ISSN 0378-5173 (doi:10.1016/j.ijpharm.2019.118952)

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Abstract

Nanoemulsions are very interesting systems as they offer capacity to encapsulate both hydrophilic and lipophilic molecules in a single particle, as well as the controlled release of chemical moieties initially entrapped in the internal droplets. In this study, we propose a new two-step modified ultrasound-assisted phase inversion approaches-phase inversion temperature (PIT) and self-emulsification, to prepare stable o/w nanoemulsions from a fully water-dilutable microemulsion template for the transdermal delivery of loratadine (a hydrophobe and as Ostwald ripening inhibitor). Firstly, the primary water-in-oil microemulsion concentrate (w/o) was formed using loratadine in the oil phase (oleic acid or coconut oil) and Tween 80 in the aqueous phase and by adjusting the PIT around 85 °C followed by stepwise dilution with water at 25 °C to initiate the formation the nanoemulsions (o/w). To assure the long-term stability, a brief application of low frequency ultrasound was employed. Combining the two low energy methods resulted in nanoemulsions prepared by mixing constant surfactant/oil ratios above the PIT with varying water volume fraction (self-emulsification) during the PIT by stepwise dilution. The kinetic stability was evaluated by measuring the droplet size with time by dynamic light scattering (DLS). The droplet size ranged 15-43 nm and did not exceed 100 nm over the period of over the 6 months indicating the system had high kinetic stability. Cryo-TEM showed the nanoemulsions droplets were monodispersed and approaching micellar structure and scale. All nanoemulsions had loratadine crystals formed within 20 days after preparation, which inclined to sediment during storage. Nanoemulsions improved the in vitro permeation of loratadine through porcine skin up to 20 times compared to the saturated solution.

Item Type:	Article
Uncontrolled Keywords:	Nanoemulsion, Phase inversion temperature (PIT) method, Nonionic Transdermal drug delivery, Ultrasound, Ostwald ripening, Coalescence
Subjects:	R Medicine > RS Pharmacy and materia medica
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > School of Science (SCI)
Last Modified:	15 Dec 2020 01:38
URI:	http://gala.gre.ac.uk/id/eprint/26383

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