Effect of Solid Lipid and Liquid Oil Ratios on Properties of Nanostructured Lipid Carriers for Oral Curcumin Delivery

Nose to Brain Delivery of Astaxanthin–Loaded Nanostructured Lipid Carriers in Rat Model of Alzheimer’s Disease: Preparation, in vitro and in vivo Evaluation

Background

Astaxanthin (AST) is a second-generation antioxidant with anti-inflammatory and neuroprotective properties and could be a promising candidate for Alzheimer's disease (AD) therapy, but is shows poor oral bioavailability due to its high lipophilicity.

Purpose

This study aimed to prepare and evaluate AST-loaded nanostructured lipid carriers (NLCs), for enhanced nose-to-brain drug delivery to improve its therapeutic efficacy in rat model of AD.

Methods

AST-NLCs were prepared using hot high-pressure homogenization technique, and processing parameters such as total lipid-to-drug ratio, solid lipid-to-liquid lipid ratio, and concentration of surfactant were optimized.

Results

The optimized AST-NLCs had a mean particle size of 142.8 ± 5.02 nm, polydispersity index of 0.247 ± 0.016, zeta potential of -32.2 ± 7.88 mV, entrapment efficiency of 94.1 ± 2.46%, drug loading of 23.5 ± 1.48%, and spherical morphology as revealed by transmission electron microscopy. Differential scanning calorimetry showed that AST was molecularly dispersed in the NLC matrix in an amorphous state, whereas Fourier transform infrared spectroscopy indicated that there is no interaction between AST and lipids. AST displayed a biphasic release pattern from NLCs; an initial burst release followed by sustained release for 24 h. AST-NLCs were stable at 4-8 ±2°C for six months. Intranasal treatment of AD-like rats with the optimized AST-NLCs significantly decreased oxidative stress, amyloidogenic pathway, neuroinflammation and apoptosis, and significantly improved the cholinergic neurotransmission compared to AST-solution. This was observed by the significant decline in the levels of malondialdehyde, nuclear factor-kappa B, amyloid beta (Aβ_1‑42), caspase-3, acetylcholinesterase, and β-site amyloid precursor protein cleaving enzyme-1 expression, and significant increase in the contents of acetylcholine and glutathione after treatment with AST-NLCs.

Conclusion

NLCs enhanced the intranasal delivery of AST and significantly improved its therapeutic properties.

Tailoring Apixaban in Nanostructured Lipid Carrier Enhancing Its Oral Bioavailability and Anticoagulant Activity

Apixaban (Apx), an oral anticoagulant drug, is a direct factor Xa inhibitor for the prophylaxis against venous thromboembolism. Apx has limited oral bioavailability and poor water solubility. The goal of this study was to improve the formulation of an Apx-loaded nanostructured lipid carrier (NLC) to increase its bioavailability and effectiveness. As solid lipid, liquid lipid, hydrophilic, and lipophilic stabilizers, stearic acid, oleic acid, Tween 80, and lecithin were used, respectively. Utilizing Box-Behnken design, the effects of three factors on NLC particle size (Y₁), zeta potential (Y₂), and entrapment efficiency percent (Y₃) were examined and optimized. The optimized formula was prepared, characterized, morphologically studied, and pharmacokinetically and pharmacodynamically assessed. The observed responses of the optimized Apx formula were 315.2 nm, -43.4 mV, and 89.84% for Y₁, Y₂, and Y₃, respectively. Electron microscopy revealed the homogenous spherical shape of the NLC particles. The in vivo pharmacokinetic study conducted in male Wistar rats displayed an increase in AUC and C_max by 8 and 2.67 folds, respectively, compared to oral Apx suspension. Moreover, the half-life was increased by 1.94 folds, and clearance was diminished by about 8 folds, which makes the NLC formula a promising sustained release system. Interestingly, the pharmacodynamic results displayed the superior effect of the optimized formula over the drug suspension with prolongation in the cuticle bleeding time. Moreover, both prothrombin time and activated partial thromboplastin time are significantly increased. So, incorporating Apx in an NLC formula significantly enhanced its oral bioavailability and pharmacodynamic activity.

Improvement of Cell Culture Methods for the Successful Generation of Human Keratinocyte Primary Cell Cultures Using EGF-Loaded Nanostructured Lipid Carriers

Human skin keratinocyte primary cultures can be established from skin biopsies with culture media containing epithelial growth factor (EGF). Although current methods are efficient, optimization is required to accelerate the procedure and obtain these cultures in less time. In the present study, we evaluated the effect of novel formulations based on EGF-loaded nanostructured lipid carriers (NLC). First, biosafety of NLC containing recombinant human EGF (NLC-rhEGF) was verified in immortalized skin keratinocytes and cornea epithelial cells, and in two epithelial cancer cell lines, by quantifying free DNA released to the culture medium. Then we established primary cell cultures of human skin keratinocytes with basal culture media (BM) and BM supplemented with NLC-rhEGF, liquid EGF (L-rhEGF), or NLC alone (NLC-blank). The results showed that cells isolated by enzymatic digestion and cultured with or without a feeder layer had a similar growth rate regardless of the medium used. However, the explant technique showed higher efficiency when NLC-rhEGF culture medium was used, compared to BM, L-rhEGF, or NLC-blank. Gene expression analysis showed that NLC-rhEGF was able to increase EGFR gene expression, along with that of other genes related to cytokeratins, cell–cell junctions, and keratinocyte maturation and differentiation. In summary, these results support the use of NLC-rhEGF to improve the efficiency of explant-based methods in the efficient generation of human keratinocyte primary cell cultures for tissue engineering use.

In vitro evaluation of albendazole-loaded nanostructured lipid carriers on Echinococcus granulosus microcysts and their prophylactic efficacy on experimental secondary hydatidosis

To enhance the therapeutic effects of albendazole (ABZ) on Echinococcus granulosus protoscoleces and metacestodes, ABZ-loaded nanostructured lipid carriers (ABZ-NLCs) are prepared by the hot high-speed homogenization method. Protoscoleces and microcysts were treated in vitro with free ABZ and ABZ-NLCs (concentrations of 1, 5, and 10 μg/ml), and the corresponding effects were monitored by methylene blue exclusion test and scanning and transmission electron microscopy. Chemoprophylactic treatment was performed on Balb/C mice 1 day before intraperitoneal injection of viable protoscoleces. The drugs were administered daily by intragastric inoculation for a period of 30 days. The prophylactic efficacy was assessed based on the number and weight of cysts developed in treated mice. The ultrastructural alterations in cysts were examined by transmission electron microscopy. After 18 days, all the protoscoleces incubated with 10 μg/ml ABZ-NLCs were killed, while 51.25 ± 4.03% of the protoscoleces incubated with 10 μg/ml free ABZ were still viable. Microcysts treated with ABZ-NLCs underwent degenerative alterations in a shorter time than when free ABZ was applied. The mean weight of the cysts recovered from mice of ABZ-NLCs group was significantly lower than that of the free ABZ group (P < 0.05), yielding prophylactic efficacy of 92.45% and 38.53%, respectively. The cysts treated with ABZ-NLCs showed marked ultrastructural changes in the germinal layer. This study demonstrated that both in vitro and in vivo treatments with ABZ-NLCs are significantly more efficient than treatment with free ABZ against E. granulosus protoscoleces, metacestodes, and prevention of cyst development in mice.

An EGF- and Curcumin-Co-Encapsulated Nanostructured Lipid Carrier Accelerates Chronic-Wound Healing in Diabetic Rats

Nanostructured lipid carriers (NLC) are capable of encapsulating hydrophilic and lipophilic drugs. The present study developed an NLC containing epidermal growth factor (EGF) and curcumin (EGF–Cur-NLC). EGF–Cur-NLC was prepared by a modified water-in-oil-in-water (w/o/w) double-emulsion method. The EGF–Cur-NLC particles showed an average diameter of 331.8 nm and a high encapsulation efficiency (81.1% and 99.4% for EGF and curcumin, respectively). In vitro cell studies were performed using two cell types, NIH 3T3 fibroblasts and HaCaT keratinocytes. The results showed no loss of bioactivity of EGF in the NLC formulation. In addition, EGF–Cur-NLC improved in vitro cell migration, which mimics the wound healing process. Finally, EGF–Cur-NLC was evaluated in a chronic wound model in diabetic rats. We found that EGF–Cur-NLC accelerated wound closure and increased the activity of antioxidant enzymes. Overall, these results reveal the potential of the NLC formulation containing EGF and curcumin to promote healing of chronic wounds.

Optimized Nanostructured Lipid Carriers Integrated into In Situ Nasal Gel for Enhancing Brain Delivery of Flibanserin

Background and Aim

Flibanserin (FLB) is a multifunctional serotonergic agent used for treating hypoactive sexual desire disorder in premenopausal women via oral administration. FLB has a reported limited oral bioavailability of 33% that could be attributed to the drug’s first-pass metabolism. In addition, FLB has a pH-dependent solubility that could be a challenging factor for drug dissolution in the body neutral fluid, and consequently, absorption via mucosal barriers. Thus, this work aims at investigating the potential of utilizing nanostructured lipid carriers (NLCs) to overcome the aforementioned drawbacks and to enhance nose-to-brain drug delivery.

Methods

Box-Behnken design was applied to explore the impact of solid lipid % (SL%, X₁), liquid lipid % (LL%, X₂), and sonication time (ST, X₃) on particle size. The optimized NLC formulation was characterized and incorporated into gellan gum in situ gel. The prepared gel was subjected to in vitro drug release, in vivo pharmacokinetic performance, and histopathological assessment in rats.

Results

Statistical analysis revealed a significant negative effect for both SL% and ST on NLCs size. In contrast, a significant positive effect was observed for the LL%. The optimized formulation showed spherical shape with vesicular size of 114.63 nm. The optimized FLB-NLC in situ gel exhibited adequate stability and enhanced in vitro release compared to raw FLB control gel. The plasma and brain concentrations of the drug after nasal administration in rats increased by more than 3–6-fold, respectively, compared to raw FLB in situ gel. In addition, the histopathological studies revealed the absence of any pathological signs.

Conclusion

The aforementioned results highlight the safety of FLB-NLC in situ nasal gel and its potential to improve the drug bioavailability and brain delivery.

Comparison of different aliphatic acid grafted N-trimethyl chitosan surface-modified nanostructured lipid carriers for improved oral kaempferol delivery

This study compared the in vitro and in vivo effects of different aliphatic acid grafted N-trimethyl chitosan (TMC) surface-modified nanostructured lipid carriers (NLC) by oral delivery. Medium-chain fatty acids, decylic acids (DA), and long-chain fatty acids, palmitic acids (PA) were selected as contrasting objects. TMC, DA grafted TMC (DA-TMC), and PA grafted TMC (PA-TMC) were successively synthesized. Kaempferol loaded NLC (KNLC), KNLC coated with DA-TMC (DA-TMC-KNLC) and PA-TMC (PA-TMC-KNLC) were fabricated, respectively. KNLC were subspherical in shape at nano-size limits. The particle size increased from 93.6 to 125.5 nm and the zeta potential changed from negative to positive due to surface-modification. The KNLC surface-modified with different aliphatic acid grafted TMC displayed a diverse release profiles at the simulative physiological environment, which contrasted that of KNLC. Pharmacokinetic studies demonstrated that the nanoparticles all could improve the AUC values and prolong blood retention times compared to that of kaempferol suspensions. Cell uptake and in situ intestinal perfusion experiments revealed that DA-TMC-KNLC and PA-TMC-KNLC could remarkably enhance cellular uptake of kaempferol into Caco-2 cells and drug absorption in each intestinal segment in comparison with KNLC, repectively. Wherein, DA-TMC-KNLC exhibits the greatest uptake and absorption efficiency as compared to kaempferol suspensions, KNLC and PA-TMC-KNLC. Collectively, DA-TMC surface-modified NLC might serve as a potential drug carrier for oral delivery of water-insoluble flavonoid ingredients.