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| Version | Summary | Created by | Modification | Content Size | Created at | Operation |
|---|---|---|---|---|---|---|
| 1 | Stefan Radnev Stefanov | + 2238 word(s) | 2238 | 2021-11-03 10:06:57 | | | |
| 2 | Vicky Zhou | Meta information modification | 2238 | 2021-11-16 09:06:26 | | |
Lipid nanoparticles (LN) are recognized as promising drug delivery systems (DDS) in treating skin disorders. Solid lipid nanoparticles (SLN) together with nanostructured lipid carriers (NLC) exhibit excellent tolerability as these are produced from physiological and biodegradable lipids. Moreover, LN applied to the skin can improve stability, drug targeting, occlusion, penetration enhancement, and increased skin hydration compared with other drug nanocarriers. Furthermore, the features of LN can be enhanced by inclusion in suitable bases such as creams, ointments, gels (i.e., hydrogel, emulgel, bigel), lotions, etc.
The skin can be affected by various pathological changes, i.e., inflammatory, neoplastic, traumatic, hormonal, degenerative, and even hereditarily determined [1]. Infectious skin diseases such as bacterial, fungal or viral affect people and cause various dermatological problems. Chronic inflammatory skin diseases such as atopic dermatitis, allergic contact dermatitis, psoriasis, etc., are a consequence of infiltration of inflammatory T cells [2]. The schematic representation of various skin disorders is shown in Figure 1 [3][4][5][6][7][8][9][10][11][12][13][14].

Lipid-based drug delivery systems (LBDDS) are formulations containing a dissolved or suspended drug substance in lipidic excipients [17]. LBDDS are a progressive strategy to formulate pharmaceuticals for topical delivery [18]. Liposomes, which are “pioneers” among lipid DDS, have been used to improve drug solubility and traditionally for topical and transdermal drug delivery.
Table 1 presents a brief overview of lipid-based drug delivery systems.
Table 1. Presentation of some lipid-based delivery systems.
| Lipid-Based Delivery System |
Description | Advantages | Disadvantages |
|---|---|---|---|
| Nanovesicular carriers | |||
| Liposomes [19] | Conventional single or multilayer vesicles. Formed by contact of biodegradable lipids with an aqueous medium. Widely used as drug carriers for hydrophilic and lipophilic molecules. | Biocompatible and biodegradable lipids. Conventional production processes. Improved local delivery. Suitable for loading both hydrophobic and hydrophilic substances. | Insufficient chemical and physical stability. Short half-life. Inadequate penetration into the viable epidermis and dermis. High production costs. Difficulties in scalability. |
| Transfersomes [20][21][22] |
Highly deformable, elastic or ultra-flexible liposomes. Vesicles, similar to conventional liposomes in terms of preparation and structure. Claimed to permeate as intact vesicles through the skin layers. Functionally deformed due to the presence of an edge activator. | Smaller vesicle size, higher elasticity. Compared with conventional liposomes—better penetration through the skin. High membrane hydrophilicity and elasticity allow them to avoid aggregation and fusion under osmotic stress, unlike the conventional liposomes. | Elasticity of these vesicles can be compromised by hydrophobic drug loading. Occlusive application and complete skin hydration limit transdermal delivery due to inhibition of transdermal hydration. Relatively high production costs. Absence of well-established regulatory guidance for skin delivery. |
| Ethosomes [23][24] | Lipid vesicles are composed of phospholipids, ethanol, and water. Similar to liposomes in terms of their preparation techniques and structure. Concentration of ethanol 20–45%. Their size decreases with an increase in the ethanol concentration. Exhibit high encapsulation efficiency. | Appropriate for both hydrophobic and hydrophilic drug loading. Enhanced skin delivery under both occlusive and nonocclusive conditions. Higher elasticity, smaller vesicle size, and higher entrapment efficiency than conventional liposomes. | High ethanol content can lead to skin irritation and toxicity. Possible structural and chemical instability during long-term storage. Need to optimize the concentration of lipids and ethanol for improved physicochemical properties and stability of ethosomes. |
| Lipid nanoparticulate carriers | |||
| Solid lipid nanoparticles [25][26] | Colloidal lipid nanoparticles are composed of a physiological biodegradable solid lipophilic matrix (solid at room temperature and body temperature), in which the drug molecules can be incorporated. | Increased drug stability. High drug payload. Incorporation of lipophilic and hydrophilic drugs. Avoidance of organic solvents. Lack of biotoxicity of the carrier. Relatively cost-effective. | SLN are incorporated into semisolid carriers such as ointments and gels due to the high water content. Potential expulsion of active compounds during storage. Cost-effective manufacturing process. |
| Nanostructure Lipid Carriers [27][28] |
Colloidal lipid nanoparticles composed of physiological mixing liquid lipid (oils) with the solid lipids, in which the liquid lipid is incorporated into the solid matrix or localized at the surface of solid particles | Improved drug loading compared with SLN. Lower water content compared with SLN. Firmly incorporates the drug substance during storage. Biodegradable and biocompatible. Large-scale production is easily possible. | Tendency to unpredictable gelation. Polymorphic transition. Low drug incorporation due to the crystalline structure of solid lipids. Lack of long-term stability data. |
| Lipospheres [29][30][31] |
Microspheres, composed of solid hydrophobic lipid core and stabilized by a monolayer of a phospholipid embedded on the surface. | Improved drug stability, especially for photo-labile drugs. Possibility for controlled drug release. Controlled particle size. High drug loading. Biodegradable and biocompatible. | Larger particle size and poor skin permeation compared with lipid-based vesicular carriers, SLN, and NLC. Poor drug loading for hydrophilic compounds. |
| LNP Type | API/Drug | Application | Reference |
|---|---|---|---|
| SLN | Doxorubicin | Doxorubicin-loaded SLN for the treatment of skin cancer. | [63] |
| SLN | Adapalene | Adapalene-loaded SLN in the gel for anti-acne treatment. | [64] |
| SLN | Triamcinolone acetonide | Triamcinolone acetonide-loaded SLN for the topical treatment of psoriasis. | [65] |
| SLN | Resveratrol, vitamin E, and epigallocatechin gallate |
SLN containing resveratrol, vitamin E, and epigallocatechin gallate for antioxidant benefits. | [66] |
| SLN | Silybin | Silybin-loaded SLN enriched gel for irritant contact dermatitis. | [67] |
| SLN | Fluconazole | Fluconazole-loaded SLN topical gel for the treatment of pityriasis versicolor. | [68] |
| SLN | Tazarotene | Tazarotene-loaded SLN for the treatment of psoriasis. | [69] |
| SLN | Miconazole nitrate | Miconazole nitrate-loaded SLN for antifungal activity. | [70] |
| SLN | Adapalene | Adapalene-loaded SLN for anti-acne therapy. | [71] |
| SLN | Isotretinoin and α-tocopherol |
SLN loaded with retinoic acid and lauric acid for the topical treatment of acne vulgaris. | [72] |
| NLC | Spironolactone | Spironolactone-loaded NLC-based gel for the effective treatment of acne vulgaris. | [73] |
| NLC | Clobetasol propionate | NLC-based topical gel of clobetasol propionate for the treatment of eczema. | [74] |
| NLC | Tacrolimus and tumor necrosis factor α siRNA |
NLC co-delivering tacrolimus and tumor necrosis factor α siRNA for the treatment of psoriasis. | [75] |
| NLC | Itraconazole | Topical NLC containing itraconazole for the treatment of fungal infections. | [76] |
| NLC | Apremilast | NLC for topical delivery of apremilast for the treatment of psoriasis. | [77] |
| NLC | Dithranol | Dithranol-loaded NLC-based gel for the treatment of psoriasis. | [78] |
| NLC | Voriconazole | Voriconazole-loaded NLC for antifungal applications. | [79] |
| NLC | Mometasone furoate | NLC-based hydrogel of mometasone furoate for the treatment of psoriasis. | [80] |
| NLC | Antimicrobial peptide nisin Z |
Antimicrobial peptide nisin Z with conventional antibiotic-loaded NLC to enhance antimicrobial activity. | [81] |
| NLC | Adapalene and vitamin C | Adapalene- and vitamin C-loaded NLC for acne treatment. | [82] |