Potential of Nano/Microemulsions for Drugs and Phytochemicals Delivery

A special issue of Pharmaceutics (ISSN 1999-4923). This special issue belongs to the section "Drug Delivery and Controlled Release".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 10485

Special Issue Editors

Pharmaceutical Sciences Graduate Program, Universidade Federal do Rio Grande do Sul, Porto Alegre 90610-000, Brazil
Interests: pharmaceutical technology; nanotechnology; natural products; essential oils
Special Issues, Collections and Topics in MDPI journals
Faculty of Pharmacy, Universidade Federal do Rio Grande do Sul, Porto Alegre 90610-000, RS, Brazil
Interests: nanoemulsions; spontaneous emulsification; skin delivery; intranasal delivery; natural products
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Nanoemulsions consist of nanoscale oil/water dispersions stabilized by an appropriate surfactant system in which the drug is incorporated into the oil core and/or adsorbed at the interface. They emerged from parenteral emulsions more than fifty years ago as they offered an appealing alternative for the administration of poorly water-soluble drugs due to their biocompatibility, stability, ability to reduce the toxicity of cytotoxic drugs, and ability to protect drugs from degradation. Nanoemulsions can be prepared via techniques that are simple and easy to scale up and that allow solubilizing high quantities of hydrophobic compounds, which represent the majority of new chemical and plant-based entities. In addition, they are the most deeply studied nanostructure systems to encapsulate essential oils that replace the oily core conferring to its bioactivities. With specific excipients, such as surfactants and polymers, physicochemical properties are improved, providing gains in mucoadhesiveness, permeability, and interaction with biological membranes. Other colloidal systems that are simple and easy to produce and which are increasingly being investigated are microemulsions. They can be produced with the same oil phase, aqueous phase, and surface active agent used to fabricate nanoemulsions but in different ratios, rendering a decreased particle size and enhanced long-term stability.

In this context, the advantages of these relatively simple colloidal systems have been exploited in different routes of administration, such as oral, transdermal, ocular, and nasal.

Taking into consideration the advantages of nano/microemulsions, for this Special Issue, original research and review articles addressing recent advances of nano/microemulsion formulations for drugs’ and phytochemicals’ delivery via different routes of administration are welcomed.

Prof. Dr. Letícia Scherer Koester
Prof. Dr. Helder Teixeira
Guest Editors

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Keywords

  • nanoemulsions
  • microemulsions
  • natural products
  • essential oils
  • drugs
  • high-pressure homogenization
  • spontaneous emulsification
  • microfluidization
  • biocompatiblity
  • titration
  • parenteral
  • oral
  • nasal
  • transdermal
  • ocular

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Published Papers (5 papers)

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Research

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14 pages, 2731 KiB  
Article
Topical Delivery of Diacetyl Boldine in a Microemulsion Formulation for Chemoprotection against Melanoma
by Ahmed Al Saqr, Manjusha Annaji, Ishwor Poudel, Mohammed F. Aldawsari, Hamad Alrbyawi, Nur Mita, Muralikrishnan Dhanasekaran, Sai H. S. Boddu, Rabin Neupane, Amit K. Tiwari and R. Jayachandra Babu
Pharmaceutics 2023, 15(3), 901; https://doi.org/10.3390/pharmaceutics15030901 - 10 Mar 2023
Cited by 3 | Viewed by 1971
Abstract
This study aimed to develop a microemulsion formulation for topical delivery of Diacetyl Boldine (DAB) and to evaluate its cytotoxicity against melanoma cell line (B16BL6) in vitro. Using a pseudo-ternary phase diagram, the optimal microemulsion formulation region was identified, and its particle size, [...] Read more.
This study aimed to develop a microemulsion formulation for topical delivery of Diacetyl Boldine (DAB) and to evaluate its cytotoxicity against melanoma cell line (B16BL6) in vitro. Using a pseudo-ternary phase diagram, the optimal microemulsion formulation region was identified, and its particle size, viscosity, pH, and in vitro release characteristics were determined. Permeation studies were performed on excised human skin using Franz diffusion cell assembly. The cytotoxicity of the formulations on B16BL6 melanoma cell lines was evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay. Two formulation compositions were selected based on the higher microemulsion area of the pseudo-ternary phase diagrams. The formulations showed a mean globule size of around 50 nm and a polydispersity index of <0.2. The ex vivo skin permeation study demonstrated that the microemulsion formulation exhibited significantly higher skin retention levels than the DAB solution in MCT oil (Control, DAB-MCT). Furthermore, the formulations showed substantially higher cytotoxicity toward B16BL6 cell lines than the control formulation (p < 0.001). The half-maximal inhibitory concentrations (IC50) of F1, F2, and DAB-MCT formulations against B16BL6 cells were calculated to be 1 µg/mL, 10 µg/mL, and 50 µg/mL, respectively. By comparison, the IC50 of F1 was 50-fold lower than that of the DAB-MCT formulation. The results of the present study suggest that microemulsion could be a promising formulation for the topical administration of DAB. Full article
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19 pages, 5447 KiB  
Article
Effect of Penetration Enhancers on Transdermal Delivery of Oxcarbazepine, an Antiepileptic Drug Using Microemulsions
by Amitkumar Virani, Vinam Puri, Hana Mohd and Bozena Michniak-Kohn
Pharmaceutics 2023, 15(1), 183; https://doi.org/10.3390/pharmaceutics15010183 - 04 Jan 2023
Cited by 5 | Viewed by 3135
Abstract
Oxcarbazepine (OXC) is an anticonvulsant drug, indicated for the treatment of the neurological disorder, epilepsy. The objective of the present study was to evaluate the transdermal delivery of OXC from microemulsions using different penetration enhancers. Transcutol® P (TRC), oleic acid (OA), cineole [...] Read more.
Oxcarbazepine (OXC) is an anticonvulsant drug, indicated for the treatment of the neurological disorder, epilepsy. The objective of the present study was to evaluate the transdermal delivery of OXC from microemulsions using different penetration enhancers. Transcutol® P (TRC), oleic acid (OA), cineole (cin), Labrasol (LS), Tween 80 (T80) and N-Methyl-Pyrrolidone (NMP) were used as penetration enhancers as well as microemulsion components. Simple formulations of OXC in propylene glycol (PG) incorporating various penetration enhancers and combination of penetration enhancers were also evaluated for transdermal delivery. Drug delivery and penetration enhancement were studied using human cadaver skin on Franz diffusion cells. The results showed that all penetration enhancers improved the rate of permeation of OXC compared to the control. The flux of drug delivery from the various formulations was found to be, in decreasing order, cin > OA + TRC > NMP > TRC > OA. Overall, microemulsions prepared using cineole, Tween 80 and Transcutol® P (TRC) were shown to be provide the best penetration enhancement for OXC. Full article
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14 pages, 2953 KiB  
Article
Effect of Hydrogel Containing Achyrocline satureioides (Asteraceae) Extract–Loaded Nanoemulsions on Wound Healing Activity
by Lucélia Albarello Balestrin, Patrícia Inês Back, Magno da Silva Marques, Gabriela de Moraes Soares Araújo, Mariana Corrêa Falkembach Carrasco, Matheus Monteiro Batista, Tony Silveira, Jamile Lima Rodrigues, Flávia Nathiely Silveira Fachel, Leticia Scherer Koester, Valquiria Linck Bassani, Ana Paula Horn, Cristiana Lima Dora and Helder Ferreira Teixeira
Pharmaceutics 2022, 14(12), 2726; https://doi.org/10.3390/pharmaceutics14122726 - 06 Dec 2022
Cited by 6 | Viewed by 1281
Abstract
Achyrocline satureioides (Lam.) DC extract–loaded nanoemulsions have demonstrated potential for wound healing, with promising effects on keratinocyte proliferation. We carried out the first in vivo investigation of the wound healing activity of a hydrogel containing A. satureioides extract–loaded nanoemulsions. We prepared hydrogels by [...] Read more.
Achyrocline satureioides (Lam.) DC extract–loaded nanoemulsions have demonstrated potential for wound healing, with promising effects on keratinocyte proliferation. We carried out the first in vivo investigation of the wound healing activity of a hydrogel containing A. satureioides extract–loaded nanoemulsions. We prepared hydrogels by adding the gelling agent (Carbopol® Ultrez) to extract-loaded nanoemulsions (~250 nm in diameter) obtained by spontaneous emulsification. The final flavonoid content in formulation was close to 1 mg/mL, as estimated by ultra-fast liquid chromatography. Permeation/retention studies using porcine ear skin showed that flavonoids reached deeper layers of pig ear skin when it was damaged (up to 3.2 µg/cm² in the dermis), but did not reach the Franz-type diffusion cell receptor fluid. For healing activity, we performed a dorsal wound model using Wistar rats, evaluating the lesion size, anti-inflammatory markers, oxidative damage, and histology. We found that extract-loaded formulations promoted wound healing by increasing angiogenesis by ~20%, reducing inflammation (tumor necrosis factor α) by ~35%, decreasing lipid damage, and improving the re-epithelialization process in lesions. In addition, there was an increase in the number of blood vessels and hair follicles for wounds treated with the formulation compared with the controls. Our findings indicate that the proposed formulation could be promising in the search for better quality healing and tissue reconstruction. Full article
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20 pages, 3415 KiB  
Article
Microemulsions Enhance the In Vitro Antioxidant Activity of Oleanolic Acid in RAW 264.7 Cells
by Chiara De Stefani, Marzia Vasarri, Maria Cristina Salvatici, Lucia Grifoni, Jose Carlos Quintela, Anna Rita Bilia, Donatella Degl’Innocenti and Maria Camilla Bergonzi
Pharmaceutics 2022, 14(10), 2232; https://doi.org/10.3390/pharmaceutics14102232 - 19 Oct 2022
Cited by 4 | Viewed by 1582
Abstract
Oleanolic acid (OA) is the main triterpenic acid of olive leaves known for numerous pharmacological properties, including antioxidant activity. However, it is poorly soluble in water and consequently with low bioavailability, which limits its pharmacological application. Microemulsions (MEs) are dispersed systems consisting of [...] Read more.
Oleanolic acid (OA) is the main triterpenic acid of olive leaves known for numerous pharmacological properties, including antioxidant activity. However, it is poorly soluble in water and consequently with low bioavailability, which limits its pharmacological application. Microemulsions (MEs) are dispersed systems consisting of two immiscible phases that promote rapid solubilization and absorption in the gastrointestinal tract. To improve both solubility and intestinal permeability of this molecule, OA has been formulated in two different microemulsions (ME-1 and ME-2). A solubility screening was carried out to select the ME components, and pseudoternary phase diagrams were constructed to evaluate the region of existence and select the appropriate amount of the constituents. ME-1 was prepared using Capmul PG-8/NF as the oily phase, and Transcutol and Tween 20 (7:3) as surfactants, while ME-2 contained Nigella oil and Isopropil myristate as the oily phase, and Transcutol HP and Cremophor EL (2:1) as surfactants. The OA solubility was increased by 1000-fold and 3000-fold in ME-1-OA and ME-2-OA, respectively. The MEs’ droplet size and the PdI were evaluated, and the stability was assessed for 8 weeks by monitoring chemical and physical parameters. The parallel artificial membrane permeability assay (PAMPA) also demonstrated an enhanced intestinal permeability of both OA formulations compared with free OA. The potential ability of both MEs to enhance the bioactivity of OA against LPS-induced oxidative stress in RAW 264.7 murine macrophages was also investigated. Overall, this study suggests that both MEs promote a bio-enhancement of the protective action of OA against the LPS-induced pro-oxidant stress in macrophages. Overall, this study suggests that MEs could be an interesting formulation to improve OA oral bioavailability with potential clinical applications. Full article
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Review

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30 pages, 2799 KiB  
Review
Antipsychotics-Loaded Nanometric Emulsions for Brain Delivery
by Patrícia C. Pires, Ana Cláudia Paiva-Santos and Francisco Veiga
Pharmaceutics 2022, 14(10), 2174; https://doi.org/10.3390/pharmaceutics14102174 - 12 Oct 2022
Cited by 6 | Viewed by 1815
Abstract
Antipsychotic drugs have numerous disabling side effects, and many are lipophilic, making them hard to formulate at high strength. Incorporating them into nanometric emulsions can increase their solubility, protect them from degradation, and increase their brain delivery, being a promising strategy to overcome [...] Read more.
Antipsychotic drugs have numerous disabling side effects, and many are lipophilic, making them hard to formulate at high strength. Incorporating them into nanometric emulsions can increase their solubility, protect them from degradation, and increase their brain delivery, being a promising strategy to overcome the current treatment gap. A thorough review was performed to assess the true potential of these formulations for antipsychotic drugs brain delivery. Intranasal administration was preferred when compared to oral or intravenous administration, since it allowed for direct brain drug transport and reduced systemic drug distribution, having increased efficacy and safety. Moreover, the developed systems increased antipsychotic drug solubility up to 4796 times (when compared to water), which is quite substantial. In the in vivo experiments, nanometric emulsions performed better than drug solutions or suspensions, leading to improved brain drug targeting, mainly due to these formulation’s excipients (surfactants and cosolvents) permeation enhancing capability, added to a small droplet size, which leaves a large surface area available for drug absorption to occur. Thus, even if it is difficult to conclude on which formulation composition leads to a best performance (high number of variables), overall nanometric emulsions have proven to be promising strategies to improve brain bioavailability of antipsychotic drugs. Full article
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