Skin permeation of buprenorphine and its ester prodrugs from lipid nanoparticles: lipid emulsion, nanostructured lipid carriers and solid lipid nanoparticles

Engineered Dutasteride-Lipid Based Nanoparticle (DST-LNP) System Using Oleic and Stearic Acid for Topical Delivery

Male pattern baldness (MPB) is a common condition that has a negative impact on the psycho-social health of many men. This study aims to engineer an alcohol-free formulation to cater for individuals who may have had allergic reactions to alcohol-based preparations. A lipid-based nanoparticle system composed of stearic and oleic acid (solid and liquid lipid) was used to deliver dutasteride (DST) for topical application. Two compositions, with oleic acid (Formulation A) and without (Formulation B), were compared to analyse the role of oleic acid as a potential active ingredient in addition to DST. DST-loaded LNP were prepared using the emulsification–ultrasonication method. All of the prepared formulations were spherical in shape in the nanometric size range (150–300 nm), with entrapment efficiencies of >75%. X-ray diffractograms revealed that DST exists in an amorphous form within the NLP matrices. The drug release behaviour from both LNP preparations displayed slow release of DST. Permeation studies through pig ear skin demonstrated that DST-LNP with oleic acid produced significantly lower permeation into the dermis compared to the formulation without oleic acid. These results suggest that the proposed formulation presents several characteristics which are novel, indicating its suitability for the dermal delivery of anti-androgenic molecules.

Development of a novel cannabinoid-loaded microemulsion towards an improved stability and transdermal delivery

The aim of this study was to develop a stable microemulsion (ME) for transdermal delivery of tetrahydrocannabinolic acid (THCA) and cannabidiolic acid (CBDA). The lipid-based vehicles were selected by screening cannabinoid solubility and the emulsifying ability of surfactants. Pseudo-ternary phase diagrams were constructed by formulation of cannabinoids with Capryol® 90 as oil phase, Tween® 80, Solutol® HS15, Procetyl® AWS, and Cremophor® RH40 as surfactants, ethanol as cosurfactant, and distilled water as the aqueous phase. A significant improvement in transmembrane flux (J_ss), permeability coefficient (K_p), and enhancement ratio (E_R) was found in one system compared to other formulations. This ME consisted of 1.0% (w/w) of cannabinoids, 5% (w/w) of Capryol® 90, 44% (w/w) S_mix (2:1, Procetyl® AWS and Ethanol) and 50.0% (w/w) of distilled water. Additionally, the effects of pH on the permeation of the cannabinoids were investigated. Based on the pH value THCA and CBDA-loaded ME exhibited the highest permeation at pH 5.17 and pH 5.25. After storing the pH-adjusted P2 ME and the optimized P2 ME for 180 days at 4℃ and 25℃, the content of cannabinoids was over 95%. Consequently, the cannabinoid-loaded ME system is a promising option for solubilizing and stabilizing lipophilic drugs like cannabinoids and utilize them for transdermal delivery.

Transdermal delivery of buprenorphine from reduced graphene oxide laden hydrogel to treat osteoarthritis

The patients with chronic pain in osteoarthritis often have insufficient pain relief from non-opioids analgesics. Buprenorphine is a promising molecule for symptomatic relief of chronic pain. The marketed parenteral injections and sublingual tablets have short duration of action (half-life = 2.7 h), which is not suitable to manage chronic pain. The purpose of this research was to design buprenorphine-loaded Pluronic F127-reduced graphene oxide transdermal (noninvasive) hydrogel to achieve sustained release of buprenorphine to manage chronic pain in osteoarthritis. Pluronic F127 was used to stabilize the reduced graphene oxide in hydrogel system. The characterization studies including Fourier transform infrared spectroscopy, X-ray diffraction, and Raman spectroscopy confirmed the synthesis of Pluronic F127-reduced graphene oxide from graphite. The transmission electron microscopy image showed flat nanosheets of reduced graphene oxide (rGO). The developed hydrogel showed desirable pH, viscosity, adhesiveness, hardness, and cohesiveness for transdermal application. The ex vivo release study demonstrated the ability of the Pluronic F127-reduced graphene oxide (P-rGO) hydrogel to prolong release up to 14 days, owing to the strong π-π interactions between the graphene oxide (GO) and the buprenorphine. In cold ethanol tail flick model, the GO hydrogel showed sustained analgesic effect in comparison with hydrogel without rGO. Thus, this study demonstrated the potential of using Pluronic F127-reduced graphene oxide nanocarriers to prolong local analgesia for effective management for chronic pain.

Enhanced transdermal delivery of lornoxicam by nanostructured lipid carrier gels modified with polyarginine peptide for treatment of carrageenan-induced rat paw edema

Background: Nanostructured lipid carriers (NLCs) are emerging as attractive drug carriers in transdermal drug delivery. The surface modification of NLCs with cell-penetrating peptides (CPPs) can enhance the skin permeation of drugs.

Purpose: The objective of the current study was to evaluate the ability of the cell-penetrating peptide (CPP) polyarginine to translocate NLCs loaded with lornoxicam (LN) into the skin layers and to evaluate its anti-inflammatory effect.

Methods: The NLCs were prepared using an emulsion evaporation and low temperature solidification technique using glyceryl monostearates, triglycerides, DOGS-NTA-Ni lipids and surfactants, and then six histidine-tagged polyarginine containing 11 arginine (R11) peptides was modified on the surface of NLCs.

Results: The developed NLCs formulated with LN and R11 (LN-NLC-R11) were incorporated into 2% HPMC gels. NLCs were prepared with a particle size of (121.81±3.61)–(145.72±4.78) nm, and the zeta potential decreased from (−30.30±2.07) to (−14.66±0.74) mV after the modification of R11 peptides. The encapsulation efficiency and drug loading were (74.61±1.13) % and (7.92±0.33) %, respectively, regardless of the surface modification. Cellular uptake assays using HaCaT cells suggested that the NLC modified with R11 (0.02%, w/w) significantly enhanced the cell internalization of nanoparticles relative to unmodified NLCs (P<0.05 or P<0.01). An in vitro skin permeation study showed better permeation-enhancing ability of R11 (0.02%, w/w) than that of other content (0.01% or 0.04%). In carrageenan-induced rat paw edema models, LN-NLC-R11 gels inhibited rat paw edema and the production of inflammatory cytokines compared with LN-NLC gels and LN gels (P<0.01).

Conclusion: In our investigation, it was strongly demonstrated that the surface modification of NLC with R11 enhanced the translocation of LN across the skin, thereby alleviating inflammation.

VitD3-loaded solid lipid nanoparticles: stability, cytotoxicity and cytokine levels

Vitamin D3 (VitD3) has several beneficial effects on many metabolic pathways such as immunity system, bone development. The aim of the study, encapsulation of VitD3 with solid lipids, determine encapsulation efficiency and biocompatibility of nanoparticles. Therefore, VitD3-loaded solid lipid nanoparticles (SLNPs) were developed by optimising ratios of VitD3, stearic acid, beeswax and sodium dodecyl sulphate (SDS). Thermal stability, degradation profile, crystallinity rate, encapsulation efficiency and release profile of SLNPs were determined. Cytotoxicity of SLNPs on HaCaT, L929 and HUVEC cells were investigated. Negatively charged and VitD3-loaded nanoparticles with diameters between 30 and 60 nm were obtained. SLNPs containing up to 5.1 mg VitD3 per 10 mg powder samples were obtained. Cell proliferations were stimulated after exposure with VitD3-loaded SLNPs. Besides, inflammatory response after exposure to VitD3-loaded SLNPs was evaluated via determining IL10 and TNF-alpha levels on THP-1 cells. According to the results, no inflammatory response was observed.

Pentyl Gallate Nanoemulsions as Potential Topical Treatment of Herpes Labialis

Previous studies have demonstrated the antiherpes activity of pentyl gallate (PG), suggesting that it could be a promising candidate for the topical treatment of human herpes labialis. PG low aqueous solubility represents a major drawback to its incorporation in topical dosage forms. Hence, the feasibility of incorporating PG into nanoemulsions, the ability to penetrate the skin, to inhibit herpes simplex virus (HSV)-1 replication, and to cause dermal sensitization or toxicity were evaluated. Oil/water nanoemulsions containing 0.5% PG were prepared by spontaneous emulsification. The in vitro PG distribution into porcine ear skin after topical application of nanoemulsions was assessed, and the in vitro antiviral activity against HSV-1 replication was evaluated. Acute dermal toxicity and risk of dermal sensitization were evaluated in rat model. Nanoemulsions presented nanometric particle size (from 124.8 to 143.7 nm), high zeta potential (from -50.1 to -66.1 mV), loading efficiency above 99%, and adequate stability during 12 months. All formulations presented anti-HSV-1 activity. PG was able to reach deeper into the dermis more efficiently from the nanoemulsion F4. This formulation as well as PG were considered safe for topical use. Nanoemulsions seem to be a safe and effective approach for topically delivering PG in the treatment of human herpes labialis infection.

Applications and limitations of lipid nanoparticles in dermal and transdermal drug delivery via the follicular route

Lipid nanoparticles (LN) such as solid lipid nanoparticles (SLN) and nanolipid carriers (NLC) feature several claimed benefits for topical drug therapy including biocompatible ingredients, drug release modification, adhesion to the skin, and film formation with subsequent hydration of the superficial skin layers. However, penetration and permeation into and across deeper skin layers are restricted due to the barrier function of the stratum corneum (SC). As different kinds of nanoparticles provide the potential for penetration into hair follicles (HF) LN are applicable drug delivery systems (DDS) for this route in order to enhance the dermal and transdermal bioavailability of active pharmaceutical ingredients (API). Therefore, this review addresses the HF as application site, published formulations of LN which showed follicular penetration (FP), and characterization methods in order to identify and quantify the accumulation of API delivered by the LN in the HF. Since LN are based on lipids that appear in human sebum which is the predominant medium in HF an increased localization of the colloidal carriers as well as a promoted drug release may be assumed. Therefore, sebum-like lipid material and a size of less or equal 640 nm are appropriate specifications for FP of particulate formulations.

Preparation and Microbiological Evaluation of Amphiphilic Kanamycin-Lipoamino Acid Ion-Pairs

Amphiphilic ion-pairs of kanamycin (KAN) were prepared by evaporation of a water-ethanol co-solution of KAN base and a lipoamino acid bearing a 12-carbon atoms alkyl side chain (LAA12), at different molar ratios. Infrared spectroscopy confirmed the structure of ion-pairs, while differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD) studies supported the formation of new saline species with a different crystalline structure than the starting components. The solubility pattern shown in a range of both aqueous and organic solvents confirmed that the ion-pairs possess an amphiphilic character. The LAA12 counter-ion showed not to improve the antibacterial activity of KAN, suggesting that such chemical strategy is not able to favor the penetration of this drug inside the bacteria cells. Nevertheless, a slight improving, i.e., a one-fold dilution, was observed in E. coli. The present study can also serve as the basis for a further evaluation of LAA ion-pairing of antibiotics, as a means to improve the loading of hydrophilic drugs into lipid-based nanocarriers.

Impact of ester promoieties on transdermal delivery of ketorolac

Different types of ketorolac ester prodrugs incorporating tert-butyl (KT), benzyl (KB), heptyl (KH), and diketorolac heptyl (DKH) promoieties were synthesized for the comparison of percutaneous penetration. The prodrugs were characterized according to their melting point, capacity factor, lipophilicity, solubility in 30% ethanol/buffer, enzymatic hydrolysis, in vitro skin permeation, hair follicle accumulation, and in vivo skin tolerance. Interactions between the prodrugs and esterases were predicted by molecular docking. Both equimolar suspensions and saturated solutions in 30% ethanol/pH 7.4 buffer were employed as the applied dose. All of the prodrugs exhibited a lower melting point than ketorolac. The lipophilicity increased in the following order: ketorolac < KT < KB < KH < DKH. The prodrugs were rapidly hydrolyzed to the parent drug in esterase medium, skin homogenate, and plasma, with KT and KB exhibiting higher degradation rates. KT exhibited the highest skin permeation, followed by KB. The flux of KT and KB exceeded that of ketorolac by 2.5-fold and twofold, respectively. KH and DKH did not improve ketorolac permeation but exhibited a sustained release behavior. KT and KH revealed selective absorption into follicles and a threefold greater follicular uptake compared with ketorolac. KB, KH, and DKH slightly but significantly increased transepidermal water loss (TEWL) after consecutive administration for 7 days, whereas ketorolac and KT exhibited no influence on TEWL. According to the experimental results, it can be concluded that an optimal balance between lipophilicity and aqueous solubility is important in the design of a successful prodrug. The acceptable skin tolerance for safe application is also an important consideration.

Squarticles as a lipid nanocarrier for delivering diphencyprone and minoxidil to hair follicles and human dermal papilla cells

Delivery of diphencyprone (DPCP) and minoxidil to hair follicles and related cells is important in the treatment of alopecia. Here we report the development of "squarticles," nanoparticles formed from sebum-derived lipids such as squalene and fatty esters, for use in achieving targeted drug delivery to the follicles. Two different nanosystems, nanostructured lipid carriers (NLC) and nanoemulsions (NE), were prepared. The physicochemical properties of squarticles, including size, zeta potential, drug encapsulation efficiency, and drug release, were examined. Squarticles were compared to a free control solution with respect to skin absorption, follicular accumulation, and dermal papilla cell targeting. The particle size of the NLC type was 177 nm; that of the NE type was 194 nm. Approximately 80% of DPCP and 60% of minoxidil were entrapped into squarticles. An improved drug deposition in the skin was observed in the in vitro absorption test. Compared to the free control, the squarticles reduced minoxidil penetration through the skin. This may indicate a minimized absorption into systemic circulation. Follicular uptake by squarticles was 2- and 7-fold higher for DPCP and minoxidil respectively compared to the free control. Fluorescence and confocal images of the skin confirmed a great accumulation of squarticles in the follicles and the deeper skin strata. Vascular endothelial growth factor expression in dermal papilla cells was significantly upregulated after the loading of minoxidil into the squarticles. In vitro papilla cell viability and in vivo skin irritancy tests in nude mice suggested a good tolerability of squarticles to skin. Squarticles provide a promising nanocarrier for topical delivery of DPCP and minoxidil.

In vivo real-time fluorescence visualization and brain-targeting mechanisms of lipid nanocarriers with different fatty ester:oil ratios

AIMS

The objective of the present work was to investigate the influence of the inner cores of lipid nanocarriers on the efficiency of brain targeting. Cetyl palmitate and squalene were respectively chosen as the solid lipid and liquid oil in the inner phase of the nanocarriers.

MATERIALS & METHODS

Nanoparticulate systems with different cetyl palmitate/squalene ratios were compared by evaluating the size, zeta potential, molecular environment, and mobility of lipids in the systems.

RESULTS

The particulate diameter ranged from 190 to 210 nm, with systems containing 100% cetyl palmitate in the matrix (solid lipid nanoparticles [SLN]) showing the smallest size, followed by systems with both cetyl palmitate and squalene (nanostructured lipid carriers [NLC]) and with 100% squalene (lipid emulsions [LE]). A cationic surfactant, Forestall, was used to produce a positive surface charge of 40-55 mW. The in vitro release was evaluated using various dyes located in different phases of the nanocarriers. The release of sulforhodamine B occurred in a sustained manner from the shell of the nanocarriers. The in vivo brain distribution of lipid nanosystems after an intravenous injection into rats was monitored by a real-time fluorescence imaging system. LE showed higher brain accumulation than SLN and NLC. NLC only exhibited a slightly higher brain accumulation compared with the aqueous control. Incorporation of sulforhodamine B into LE could prolong its retention in the brain from 20 to 50 min. The results were further confirmed by imaging the entire brain and brain slices. The specific association of lipid nanocarriers with rat brain endothelial cells (bEnd3) was demonstrated using fluorescence microscopy. The cellular uptake of LE and SLN was higher compared with NLC and the aqueous control. LE were observed to be internalized by cells through caveola-mediated and macropinocytotic energy-dependent endocytosis.

CONCLUSION

The experimental profiles indicated that LE with moderate additives are a promising brain-targeting nanocarrier. The composition of the lipid matrix played a significant role in delivering compounds to the brain.

Physicochemical characterization and in vivo bioluminescence imaging of nanostructured lipid carriers for targeting the brain: apomorphine as a model drug

Nanostructured lipid carriers (NLCs) were prepared to investigate whether the duration of brain targeting and accumulation of drugs in the brain can be improved by intravenous delivery. NLCs were developed using cetyl palmitate as the lipid matrix, squalene as the cationic surfactant, and Pluronic F68, polysorbate 80 and polyethylene glycol as the interfacial additives. Solid lipid nanoparticles (SLNs) and lipid emulsions (LEs) were also prepared for comparison. An anti-Parkinson's drug, apomorphine, was used as the model drug. Nuclear magnetic resonance and differential scanning calorimetry showed possible interactions between the solid and liquid lipids in the inner core. The lipid nanoparticles with different compositions were characterized by mean size, zeta potential, apomorphine encapsulation and in vitro drug release. NLCs were 370-430 nm in size, which was between the sizes of the SLNs and LEs. A cationic surfactant was used to produce a positive surface charge of 42-50 mV. The base form of apomorphine was successfully entrapped by NLCs with an entrapment percentage of > 60%. The loading of apomorphine in nanoparticles resulted in a slower release behavior compared to the aqueous solution, with LEs showing the lowest release. In vivo real-time bioluminescence imaging of the rat brain revealed that NLCs could be targeted, through certain vessels, to selected brain regions. This effect was further confirmed by imaging the entire brain and brain slices. The results indicated that NLCs with moderate additives are a promising controlled-release and drug-targeting system.

Translocation of cell penetrating peptide engrafted nanoparticles across skin layers

The objective of the current study was to evaluate the ability of cell penetrating peptides (CPP) to translocate the lipid payload into the skin layers. Fluorescent dye (DID-oil) encapsulated nano lipid crystal nanoparticles (FNLCN) were prepared using Compritol, Miglyol and DOGS-NTA-Ni lipids by hot melt homogenization technique. The FNLCN surface was coated with TAT peptide (FNLCNT) or control YKA peptide (FNLCNY) and in vitro rat skin permeation studies were performed using Franz diffusion cells. Observation of lateral skin sections obtained using cryotome with a confocal microscope demonstrated that skin permeation of FNLCNT was time dependent and after 24h, fluorescence was observed upto a depth of 120 microm which was localized in the hair follicles and epidermis. In case of FNLCN and FNLCNY formulations fluorescence was mainly observed in the hair follicles. This observation was further supported by confocal Raman spectroscopy where higher fluorescence signal intensity was observed at 80 and 120 microm depth with FNLCNT treated skin and intensity of fluorescence peaks was in the ratio of 2:1:1 and 5:3:1 for FNLCNT, FNLCN, and FNLCNY treated skin sections, respectively. Furthermore, replacement of DID-oil with celecoxib (Cxb), a model lipophilic drug showed similar results and after 24h, the CXBNT formulation increased the Cxb concentration in SC by 3 and 6 fold and in epidermis by 2 and 3 fold as compared to CXBN and CXBNY formulations respectively. Our results strongly suggest that CPP can translocate nanoparticles with their payloads into deeper skin layers.