Essential oils are natural products with a complex composition. Terpenes are the most common class of chemical compounds present in essential oils. Terpenes and the essential oils containing them are widely used and investigated by their pharmacological properties and permeation-enhancing ability. However, many terpenes and essential oils are sensitive to environmental conditions, undergoing volatilization and chemical degradation. In order to overcome the chemical instability of some isolated terpenes and essential oils, the encapsulation of these compounds in nanostructured systems (polymeric, lipidic, or molecular complexes) has been employed. In addition, nanoencapsulation can be of interest for pharmaceutical applications due to its capacity to improve the bioavailability and allow the controlled release of drugs. Topical drug administration is a convenient and non-invasive administration route for both local and systemic drug delivery. The present review focuses on describing the current status of research concerning nanostructured delivery systems containing isolated terpenes and/or essential oils designed for topical administration and on discussing the use of terpenes and essential oils either for their biological activities or as permeation enhancers in pharmaceutic formulations.
Copaiba oil is used as a popular medicine in the Amazonian forest region, especially due to its anti-inflammatory properties. In this paper, we describe the formulation of hydrogel containing copaiba oil nanoemulsions (with positive and negative charges), its skin permeation, and its anti-inflammatory activity in two in vivo models: mouse ear edema and rat paw edema. Three hydrogels were tested (Carbopol, hydroxyethylcellulose and chitosan), but only Carbopol and hydroxyethylcellulose hydrogels presented good stability and did not interfere with the nanoemulsions droplet size and polydispersity index. In skin permeation assay, both formulations, positively charged nanoemulsion (PCN) and negatively charged nanoemulsion (NCN), presented a high retention in epidermis (9.76 ± 2.65 μg/g and 7.91 ± 2.46 μg/cm, respectively) followed by a smaller retention in the dermis (2.43 ± 0.91 and 1.95 ± 0.56 μg/cm, respectively). They also presented permeation to the receptor fluid (0.67 ± 0.22 and 1.80 ± 0.85 μg/cm, respectively). In addition, anti-inflammatory effect was observed to NCN and PCN with edema inhibitions of 69 and 67% in mouse ear edema and 32 and 72% in rat paw edema, respectively. Histological cuts showed the decrease of inflammatory factors, such as dermis and epidermis hyperplasia and inflammatory cells infiltration, confirming the anti-inflammatory effect from both copaiba oil nanoemulsions incorporated in hydrogel.
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The human nail is a unique barrier with a keratinized constitution that favors protection and
fine touch. However, many disorders can affect the nail, among them, are the onychomycosis and psoriasis.
Systemic oral therapy has been applied to treat these diseases, even presenting disadvantages,
including side effects, drug interactions, contraindications, toxicity, high cost and low patient compliance.
A great option to succeed in dealing with the problems associated with oral therapy is the topical
administration of drugs. However, nail composition, low diffusion through ungual route and reduced
tissue bioavailability for topical treatments are limiting factors. These drawbacks can be overcome by
promoting penetration through the nails by employing penetration enhancers. The review focuses on
patents that highlight permeation enhancers applied to nail drug delivery for the treatment of onychomycosis
and psoriasis. Literature and patent searches were conduced regarding the topic of interest.
The substantial literature and patent search revealed that permeation enhancers, especially chemicals,
are great strategies for promoting the ungual delivery of drugs. Nail topical therapy containing permeation
enhancers is an attractive option for delivering localized treatments.
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