Surface-modified solid lipid nanoparticles for oral delivery of docetaxel: enhanced intestinal absorption and lymphatic uptake

2-Monoacylglycerol Mimetic Liposomes to Promote Intestinal Lymphatic Transport for Improving Oral Bioavailability of Dihydroartemisinin

Purpose

Reducing the first-pass hepatic effect via intestinal lymphatic transport is an effective way to increase the oral absorption of drugs. 2-Monoacylglycerol (2-MAG) as a primary digestive product of dietary lipids triglyceride, can be assembled in chylomicrons and then transported from the intestine into the lymphatic system. Herein, we propose a biomimetic strategy and report a 2-MAG mimetic nanocarrier to target the intestinal lymphatic system via the lipid absorption pathway and improve oral bioavailability.

Methods

The 2-MAG mimetic liposomes were designed by covalently bonding serinol (SER) on the surface of liposomes named SER-LPs to simulate the structure of 2-MAG. Dihydroartemisinin (DHA) was chosen as the model drug because of its disadvantages such as poor solubility and high first-pass effect. The endocytosis and exocytosis mechanisms were investigated in Caco-2 cells and Caco-2 cell monolayers. The capacity of intestinal lymphatic transport was evaluated by ex vivo biodistribution and in vivo pharmacokinetic experiments.

Results

DHA loaded SER-LPs (SER-LPs-DHA) had a particle size of 70 nm and a desirable entrapment efficiency of 93%. SER-LPs showed sustained release for DHA in the simulated gastrointestinal environment. In vitro cell studies demonstrated that the cellular uptake of SER-LPs primarily relied on the caveolae- rather than clathrin-mediated endocytosis pathway and preferred to integrate into the chylomicron assembly process through the endoplasmic reticulum/Golgi apparatus route. After oral administration, SER-LPs efficiently promoted drug accumulation in mesenteric lymphatic nodes. The oral bioavailability of DHA from SER-LPs was 10.40-fold and 1.17-fold larger than that of free DHA and unmodified liposomes at the same dose, respectively.

Conclusion

SER-LPs improved oral bioavailability through efficient intestinal lymphatic transport. These findings of the current study provide a good alternative strategy for oral delivery of drugs with high first-pass hepatic metabolism.

A Window for Enhanced Oral Delivery of Therapeutics via Lipid Nanoparticles

Oral administration of dosage forms is convenient and beneficial in several respects. Lipid nanoparticulate dosage forms have emerged as a useful carrier system in deploying low solubility drugs systemically, particularly class II, III, and IV drugs of the Biopharmaceutics Classification System. Like other nanoparticulate delivery systems, their low size-to-volume ratio facilitates uptake by phagocytosis. Lipid nanoparticles also provide scope for high drug loading and extended-release capability, ensuring diminished systemic side effects and improved pharmacokinetics. However, rapid gastrointestinal (GI) clearance of particulate delivery systems impedes efficient uptake across the mucosa. Mucoadhesion of dosage forms to the GI mucosa results in longer transit times due to interactions between the former and mucus. Delayed transit times facilitate transfer of the dosage form across the mucosa. In this regard, a balance between mucoadhesion and mucopenetration guarantees optimal systemic transfer. Furthermore, the interplay between GI anatomy and physiology is key to ensuring efficient systemic uptake. This review captures salient anatomical and physiological features of the GI tract and how these can be exploited for maximal systemic delivery of lipid nanoparticles. Materials used to impart mucoadhesion and examples of successful mucoadhesive lipid nanoformulations are highlighted in this review.

Experimental and computational models to investigate intestinal drug permeability and metabolism

Oral administration is the preferred route for drug administration that leads to better therapy compliance. The intestine plays a key role in the absorption and metabolism of oral drugs, therefore, new intestinal models are being continuously proposed, which contribute to the study of intestinal physiology, drug screening, drug side effects, and drug-drug interactions.Advances in pharmaceutical processes have produced more drug formulations, causing challenges for intestinal models. To adapt to the rapid evolution of pharmaceuticals, more intestinal models have been created. However, because of the complexity of the intestine, few models can take all aspects of the intestine into account, and some functions must be sacrificed to investigate other areas. Therefore, investigators need to choose appropriate models according to the experimental stage and other requirements to obtain the desired results.To help researchers achieve this goal, this review summarised the advantages and disadvantages of current commonly used intestinal models and discusses possible future directions, providing a better understanding of intestinal models.

Clove Oil Endorsed Transdermal Flux of Dronedarone Hydrochloride Loaded Bilosomal Nanogel: Factorial Design, In vitro Evaluation and Ex vivo Permeation

The goal of this study was to develop a bilosomal gel formulation to enhance transdermal permeability of dronedarone hyrdrochloride (DRN) which suffers from poor oral absorption and limited bioavailability. To overcome this obstacle, bilosomes were successfully prepared using 2³ full-factorial design. Span®40, cholesterol, sodium deoxycholate (bile salt), clove oil (permeability enhancer), and either Tween® 60 or Tween® 80 (edge activator) were used in bilosome preparation by ethanol injection method. In this design, independent variables were X1, edge activator type; X2, edge activator amount (mg); and X3, permeability enhancer concentration (% w/v). Optimal formula (B2) of the highest desirability of (0.776) demonstrated minimum vesicle size (VS) of 312.4 ± 24.42 nm, maximum absolute value of zeta potential (ZP) - 36.17 ± 2.57 mV, maximum entrapment efficiency (EE %) of 80.95 ± 3.01%, maximum deformability Index (DI) of 8.24 ± 1.26 g and maximum drug flux after 12 h (J₁₂) of 21.23 ± 1.54 µg/cm² h upon ex vivo permeation study. After 12 h, 70.29 ± 6.46% of DRN was released from B2. TEM identification of B2 showed spherical shaped nanosized vesicles which were physically stable for 3 months at different temperatures. B2 was incorporated into carboxymethylcellulose gel base for easiness of dermal application. B2 gel demonstrated good physical properties, non-Newtonian psuedoplastic flow, and enhanced release (57.0 ± 8.68% of DRN compared to only 13.3 ± 1.2% released from drug suspension after 12 h) and enhanced skin permeation.

Lymphatic targeting for therapeutic application using nanoparticulate systems

The lymphatic system has grasped attention of researchers to a greater extent. The conventional methods of lymphatic delivery are now being modified to include nanotechnology to enhance the targeting of the drug at the specific pathological site. Scientists have worked successfully on different drug loaded nanocarriers that are modulated for the lymphatic system targeting for the treatment of various fatal diseases. Huge strides have been made in methods of delivery of these drugs either individually or in combination along with nanoparticles, therapeutic genes, and vaccines. However, the products introduced for commercial use are almost near nil. Altogether, there are challenges that need to be resolved and studies that are meant to be done for further improvements. The current review focuses on the understanding and pathophysiology of the lymphatic system and changes that occur during disease, drug characteristics, and physicochemical parameters that influence the lymphatic uptake of drugs and different nanocarriers. We further highlight different potential results obtained over the years with nanocarriers and other delivery methods to effectively target the lymphatic system for their therapeutic application. The challenges and drawbacks governing the lack of products available clinically have also been discussed.

Design and Evaluation of Two-Step Biorelevant Dissolution Methods for Docetaxel Oral Formulations

Dissolution is a pivotal tool for oral formulations. Dissolution could be used to either reduce the risk of product failure through quality control or predict and understand in vivo performance of drug formulations. The latter is always challenging because multiple factors such as selection of media, gastrointestinal components, physiological factors, consideration of fasted and fed state are involved. Previously published dissolution methods such as one-step dissolution in individual simulated gastric fluid, simulated intestinal fluid, or phosphate buffer saline did not signify the realistic gastrointestinal transit effect. Docetaxel (DTX), a poorly water-soluble drug, is commercially available only as injectable dosage forms, and thus many publications studied the development of oral DTX formulations. In our previous report, we developed oral lipid-based DTX granules that showed higher oral absorption in rats compared to DTX powder. However, one-step dissolution in simulated gastric fluid showed no difference between DTX granules and DTX powder. Therefore, the present study aimed to develop new two-step biorelevant dissolution methods for DTX oral formulations. In the study, new two-step biorelevant dissolution methods in fasted or fed states with pancreatin were developed and compared with other previously reported dissolution methods. The new two-step biorelevant dissolution methods successfully discriminated the difference of dissolution between DTX granules and DTX powder, which reflected the in vivo difference of absorption of these two formulations. Moreover, food effects were confirmed for DTX. The new dissolution methods have the potential to be used to predict and understand in vivo performance of oral solid dosage forms.

Drug delivery to the intestinal lymph by oral formulations

Oral drug delivery systems (DDS) targeting lymphocytes in intestinal lymphatic vessels, ducts, and nodes are useful for treating diverse diseases. The intestinal lymph harbors numerous lymphocyte subsets, and DDS containing lipids such as triglycerides and fatty acids can deliver drugs to the lymph through the chylomicron pathway. DDS are efficient, thus allowing the administration of reduced drug doses, which mitigate systemic adverse effects. Here we review orally administered lipid formulations comprising oil solutions, suspensions, micro/nanoemulsions, self-micro/nano emulsifying DDS, liposomes, micelles, solid lipid nanoparticles, and nanostructured lipid carriers for targeting drugs to the lymph. We first describe the structures of lymphatic vessels and lymph nodes and the oral absorption of lipids and drugs into the intestinal lymph. We next summarize the effects of the properties and amounts of lipids and drugs delivered into the lymph and lymphocytes, as well as their effects on drug delivery ratios of lymph to blood. Finally, we describe lymphatic DDS containing saquinavir, tacrolimus, and methotrexate, and their potency that reduce drug concentrations in blood, which are associated with systemic adverse effects.

Safety and Toxicity Issues of Therapeutically Used Nanoparticles from the Oral Route

The emerging science of nanotechnology sparked a research attention in its potential benefits in comparison to the conventional materials used. Oral products prepared via nanoparticles (NPs) have garnered great interest worldwide. They are used commonly to incorporate nutrients and provide antimicrobial activity. Formulation into NPs can offer opportunities for targeted drug delivery, improve drug stability in the harsh environment of the gastrointestinal (GI) tract, increase drug solubility and bioavailability, and provide sustained release in the GI tract. However, some issues like the management of toxicity and safe handling of NPs are still debated and should be well concerned before their application in oral preparations. This article will help the reader to understand safety issues of NPs in oral drug delivery and provides some recommendations to the use of NPs in the drug industry.

Do Lipid-based Nanoparticles Hold Promise for Advancing the Clinical Translation of Anticancer Alkaloids?

Since the commercialization of morphine in 1826, numerous alkaloids have been isolated and exploited effectively for the betterment of mankind, including cancer treatment. However, the commercialization of alkaloids as anticancer agents has generally been limited by serious side effects due to their lack of specificity to cancer cells, indiscriminate tissue distribution and toxic formulation excipients. Lipid-based nanoparticles represent the most effective drug delivery system concerning clinical translation owing to their unique, appealing characteristics for drug delivery. To the extent of our knowledge, this is the first review to compile in vitro and in vivo evidence of encapsulating anticancer alkaloids in lipid-based nanoparticles. Alkaloids encapsulated in lipid-based nanoparticles have generally displayed enhanced in vitro cytotoxicity and an improved in vivo efficacy and toxicity profile than free alkaloids in various cancers. Encapsulated alkaloids also demonstrated the ability to overcome multidrug resistance in vitro and in vivo. These findings support the broad application of lipid-based nanoparticles to encapsulate anticancer alkaloids and facilitate their clinical translation. The review then discusses several limitations of the studies analyzed, particularly the discrepancies in reporting the pharmacokinetics, biodistribution and toxicity data. Finally, we conclude with examples of clinically successful encapsulated alkaloids that have received regulatory approval and are undergoing clinical evaluation.

Enhancement of Docetaxel Absorption Using Ritonavir in an Oral Milk-Based Formulation

OBJECTIVE

The current study aimed to develop a novel milk-based formulation of docetaxel, a sparingly soluble antineoplastic agent, administered so far exclusively by the intravenous route and evaluate its oral bioavailability.

METHODS

Pre-formulation studies included the determination of docetaxel solubility in water-alcohol mixtures as well as short-term content uniformity experiments of the final formulation. The pharmacokinetic (PK) performance of the developed milk-based formulations was further evaluated in vivo in mice using ritonavir, a potent P-glycoprotein inhibitor, as an absorption enhancer of docetaxel and the marketed intravenous docetaxel formulation, Taxotere®, as a control.

RESULTS

In vivo PK results in mice showed that all the administered oral docetaxel formulations had limited absorption in the absence of ritonavir. On the contrary, ritonavir co-administration given as pre-treatment significantly enhanced oral bioavailability of both the marketed and milk-based docetaxel formulations; an even more marked increase in drug exposure was observed when ritonavir was incorporated within the docetaxel milk-based formulation. The fixed-dose combination also showed a more prolonged absorption of the drug compared to separate administrations.

CONCLUSIONS

The current study provides insights for the discovery of a novel milk-based formulation that could potentially serve as an alternative, non-toxic and patient-friendly carrier for an acceptable docetaxel oral chemotherapy.

Investigation of the Factors Responsible for the Poor Oral Bioavailability of Acacetin in Rats: Physicochemical and Biopharmaceutical Aspects

Acacetin, an important ingredient of acacia honey and a component of several medicinal plants, exhibits therapeutic effects such as antioxidative, anticancer, anti-inflammatory, and anti-plasmodial activities. However, to date, studies reporting a systematic investigation of the in vivo fate of orally administered acacetin are limited. Moreover, the in vitro physicochemical and biopharmaceutical properties of acacetin in the gastrointestinal (GI) tract and their pharmacokinetic impacts remain unclear. Therefore, in this study, we aimed to systematically investigate the oral absorption and disposition of acacetin using relevant rat models. Acacetin exhibited poor solubility (≤119 ng/mL) and relatively low stability (27.5–62.0% remaining after 24 h) in pH 7 phosphate buffer and simulated GI fluids. A major portion (97.1%) of the initially injected acacetin dose remained unabsorbed in the jejunal segments, and the oral bioavailability of acacetin was very low at 2.34%. The systemic metabolism of acacetin occurred ubiquitously in various tissues (particularly in the liver, where it occurred most extensively), resulting in very high total plasma clearance of 199 ± 36 mL/min/kg. Collectively, the poor oral bioavailability of acacetin could be attributed mainly to its poor solubility and low GI luminal stability.

Fabrication and Appraisal of Simvastatin via Tailored Niosomal Nanovesicles for Transdermal Delivery Enhancement: In Vitro and In Vivo Assessment

Simvastatin (SIM) is a HMG-CoA reductase inhibitor employed in the management of hyperlipidemia. However, its low bioavailability limits its clinical efficacy. The objective of this study was to overcome the poor bioavailability of SIM via the transdermal application of a SIM-loaded niosomal gel. Niosomes loaded with SIM were fabricated by means of the thin-film hydration method and optimized through a 3³-factorial design utilizing Design Expert^® software. The prepared niosomes were evaluated for entrapment efficiency (EE%), zeta potential, vesicle size, and cumulative percentage of drug release. The optimum niosomal formulation was loaded on the gel and evaluated for physical properties such as color, clarity, and homogeneity. It was also evaluated for spreadability, and the cumulative % drug release. The best niosomal gel formula was appraised for ex vivo permeation as well as pharmacokinetic study. The SIM-loaded niosomes showed EE% between 66.7–91.4%, vesicle size between 191.1–521.6 nm, and zeta potential ranged between −0.81–+35.6 mv. The cumulative percentage of drug released was ranged from 55% to 94% over 12 h. SIM-loaded niosomal gels were clear, homogenous, spreadable, and the pH values were within the range of physiological skin pH. Furthermore, about 73.5% of SIM was released within 24 h, whereas 409.5 µg/cm² of SIM passed through the skin over 24 h in the ex vivo permeation study. The pharmacokinetic study revealed higher AUC_0–∞ and Cmax with topical application of SIM-loaded niosomal gel compared to topical SIM gel or oral SIM suspension. The topical application of SIM-loaded niosomal gel ascertained the potential percutaneous delivery of SIM.

Topical Nano-Vesicular Spanlastics of Celecoxib: Enhanced Anti-Inflammatory Effect and Down-Regulation of TNF-α, NF-кB and COX-2 in Complete Freund's Adjuvant-Induced Arthritis Model in Rats

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disease that underlies chronic inflammation of the synovial membrane. Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used to treat RA. However, a long list of adverse events associated with long-term treatment regimens with NSAIDs negatively influences patient compliance and therapeutic outcomes.

AIM

The aim of this work was to achieve site-specific delivery of celecoxib-loaded spanlastic nano-vesicle-based delivery system to the inflamed joints, avoiding systemic administration of large doses.

METHODOLOGY

To develop spanlastic nanovesicles for transdermal delivery of celecoxib, modified injection method was adopted using Tween 80 or Brij as edge activators. Entrapment efficiency, vesicle size, ex vivo permeation, and morphology of the prepared nano-vesicles were characterized. Carbopol-based gels containing the selected formulations were prepared, and their clarity, pH, rheological performance, and ex vivo permeation were characterized. Celecoxib-loaded niosomes and noisome-containing gels were developed for comparison. The in vivo efficacy of the selected formulations was evaluated in a rat model of Freund's complete adjuvant-induced arthritis. Different inflammatory markers including TNF-α, NF-кB and COX-2 were assessed in paw tissue before and after treatment.

RESULTS

The size and entrapment efficiency of the selected spanlastic nano-vesicle formulation were 112.5 ± 3.6 nm, and 83.6 ± 2.3%, respectively. This formulation has shown the highest transdermal flux and permeability coefficient compared to the other investigated formulations. The spanlastics-containing gel of celecoxib has shown transdermal flux of 6.9 ± 0.25 µg/cm2/hr while the celecoxib niosomes-containing gel and unprocessed celecoxib-loaded gel have shown 5.2 ± 0.12 µg/cm2/hr and 0.64 ± 0.09 µg/cm2/hr, respectively. In the animal model of RA, the celecoxib-loaded spanlastics-containing gel significantly reduced edema circumference and significantly suppressed TNF-α, NF-кB and COX-2 levels compared to the niosomes-containing gel, the marketed diclofenac sodium gel, and unprocessed celecoxib-loaded gel.

CONCLUSION

The spanlastic nano-vesicle-containing gel represents a more efficient site-specific treatment for topical treatment of chronic inflammation like RA, compared to commercial and other conventional alternatives.

Molecular Magnetic Resonance Imaging with Contrast Agents for Assessment of Inflammatory Bowel Disease: A Systematic Review

Background and Aims

Magnetic resonance imaging (MRI) has taken an important role in the diagnosis of inflammatory bowel diseases (IBD). In the wake of current advances in nanotechnology, the drug delivery industry has seen a surge of nanoparticles advertising high specificity in target imaging. Given the rapid development of the field, this review has assembled related articles to explore whether molecular contrast agents can improve the diagnostic capability on gastrointestinal imaging, especially for IBD.

Methods

Relevant articles published between 1998 and 2018 from a literature search of PubMed and EMBASE were reviewed. Data extraction was performed on the studies' characteristics, experimental animals, modelling methods, nanoparticles type, magnetic resonance methods, and means of quantitative analysis.

Results

A total of 8 studies were identified wherein the subjects were animals, and all studies employed MR equipment. One group utilized a perfluorocarbon solution and the other 7 groups used either magnetic nanoparticles or gadolinium- (Gd-) related nanoparticles for molecular contrast. With ultrasmall superparamagnetic iron oxide (USPIO) particles and Gd-related nanoparticles, signal enhancements were found in the mucosa or with focal lesion of IBD-related model in T1-weighted images (T1WI), whereas superparamagnetic iron oxide (SPIO) particles showed a signal decrease in the intestinal wall of the model in T1WI or T2-weighted images. The signal-to-noise ratio (SNR) was employed to analyze bowel intensity in 3 studies. And the percentage of normalized enhancement was used in 1 study for assessing the severity of inflammation.

Conclusion

Molecular MRI with contrast agents can improve the early diagnosis of IBD and quantitate the severity of inflammation in experimental studies.

Docetaxel-loaded solid lipid nanoparticles prevent tumor growth and lung metastasis of 4T1 murine mammary carcinoma cells

BACKGROUND

Metastasis causes the most breast cancer-related deaths in women. Here, we investigated the antitumor effect of solid lipid nanoparticles (SLN-DTX) when used in the treatment of metastatic breast tumors using 4T1-bearing BALB/c mice.

RESULTS

Solid lipid nanoparticles (SLNs) were produced using the high-energy method. Compritol 888 ATO was selected as the lipid matrix, and Pluronic F127 and Span 80 as the surfactants to stabilize nanoparticle dispersion. The particles had high stability for at least 120 days. The SLNs' dispersion size was 128 nm, their polydispersity index (PDI) was 0.2, and they showed a negative zeta potential. SLNs had high docetaxel (DTX) entrapment efficiency (86%), 2% of drug loading and showed a controlled drug-release profile. The half-maximal inhibitory concentration (IC₅₀) of SLN-DTX against 4T1 cells was more than 100 times lower than that of free DTX after 24 h treatment. In the cellular uptake test, SLN-DTX was taken into the cells significantly more than free DTX. The accumulation in the G2-M phase was significantly higher in cells treated with SLN-DTX (73.7%) than in cells treated with free DTX (23.0%), which induced subsequent apoptosis. TEM analysis revealed that SLN-DTX internalization is mediated by endocytosis, and fluorescence microscopy showed DTX induced microtubule damage. In vivo studies showed that SLN-DTX compared to free docetaxel exhibited higher antitumor efficacy by reducing tumor volume (p < 0.0001) and also prevented spontaneous lung metastasis in 4T1 tumor-bearing mice. Histological studies of lungs confirmed that treatment with SLN-DTX was able to prevent tumor. IL-6 serum levels, ki-67 and BCL-2 expression were analyzed and showed a remarkably strong reduction when used in a combined treatment.

CONCLUSIONS

These results indicate that DTX-loaded SLNs may be a promising carrier to treat breast cancer and in metastasis prevention.

Mitigation of Rheumatic Arthritis in a Rat Model via Transdermal Delivery of Dapoxetine HCl Amalgamated as a Nanoplatform: In vitro and in vivo Assessment

Purpose

Dapoxetine HCl (DH), a selective serotonin reuptake inhibitor, may be useful for the treatment of rheumatic arthritis (RA). The purpose of this study was to investigate the therapeutic efficacy of transdermal delivery of DH in transethosome nanovesicles (TENVs). This novel delivery of DH may overcome the drawbacks associated with orally administered DH and improve patient compliance.

Methods

DH-TENV formulations were prepared using an injection- sonication method and optimized using a 3³ Box-Behnken-design with Design Expert^® software. The TENV formulations were assessed for entrapment efficiency (EE-%), vesicle size, zeta potential, in vitro DH release, and skin permeation. The tolerability of the optimized DH-TENV gel was investigated using a rat skin irritation test. A pharmacokinetic analysis of the optimized DH-TENV gel was also conducted in rats. Moreover, the anti-RA activity of the optimized DH-TENV gel was assessed based on the RA-specific marker anti-cyclic cirtullinated peptide antibody (anti-CCP), the cartilage destruction marker cartilage oligomeric matrix protein (COMP) and the inflammatory marker interleukin-6 (IL-6). Level of tissue receptor activator of nuclear factor kappa-Β ligand (RANKL) were also assessed.

Results

The optimized DH-TENV formulation involved spherical nanovesicles that had an appropriate EE- % and skin permeation characteristic. The DH-TENV gel was well tolerated by rats. The pharmacokinetics analysis showed that the optimized DH-TENV gel boosted the bioavailability of the DH by 2.42- and 4.16-fold compared to the oral DH solution and the control DH gel, respectively. Moreover, it significantly reduced the serum anti-CCP, COMP and IL-6 levels and decreased the RANKL levels. Furthermore, the DH-TENV gel attenuated histopathological changes by almost normalizing the articular surface and synovial fluid.

Conclusion

The results indicate that DH-TENVs can improve transdermal delivery of DH and thereby alleviate RA.

Development of a RP-HPLC method for analysis of docetaxel in tumor-bearing mice plasma and tissues following injection of docetaxel-loaded pH responsive targeting polymeric micelles

Background and purpose:

A simple, rapid, and sensitive reversed-phase high performance liquid chromatography (RP-HPLC) method based on liquid-liquid extraction was developed and validated for determination of docetaxel (DTX) in plasma and homogenate tissues of tumor-bearing mice.

Experimental approach:

Samples were spiked with celecoxib as the internal standard and separation was achieved on a μ-Bondapak C18 HPLC column. The mobile phase consisted of a mixture of acetonitrile/water (40/60 v/v) at flow rate of 1.2 mL/min and the effluent was monitored at 230 nm.

Results:

Calibration curves were linear over the concentration range of 0.1-10 μg/mL of DTX in plasma and 0.25-50 μg/mL in tissue homogenates with acceptable precision and accuracy. The mean recoveries of the drug from plasma extraction was 94.6 ± 1.44% while those of tissue homogenates ranged from 73.5 ± 3.2 to 85.3 ± 2.8% depending on the type of tissues examined. DTX was stable in biological samples with no evidence of degradation during 3 freeze-thaw cycles and two months of storage at -70 ± 15 °C. The developed HPLC method was applied to quantify DTX in the mouse plasma and tissues after intravenous administration of 7.5 mg equivalent DTX/kg dose of DTX-loaded folic acid-polyethylene glycol-heparin-tocopherol (FA-PEG-HEP-CA-TOC) micelle formulation to female Balb/c mice.

Conclusion:

A simple, sensitive, rapid, accurate, and prudent RP-HPLC method was developed, validated, and applied for DTX determination in plasma and tissues.

Transdermal delivery of fluvastatin sodium via tailored spanlastic nanovesicles: mitigated Freund's adjuvant-induced rheumatoid arthritis in rats through suppressing p38 MAPK signaling pathway

The current study aimed to encapsulate fluvastatin sodium (FVS), a member of the statins family possessing pleiotropic effects in rheumatoid arthritis (RA), into spanlastic nanovesicles (SNVs) for transdermal delivery. This novel delivery could surmount FVS associated oral encumbrances such as apparent first-pass effect, poor bioavailability and short elimination half-life, hence, accomplishing platform for management of RA. To consummate this objective, FVS-loaded SNVs were elaborated by thin film hydration method, utilizing either Span 60 or Span 80, together with Tween 80 or Brij 35 as an edge activator according to full factorial design (2⁴). Applying Design-Expert^® software, the influence of formulation variables on SNVs physicochemical properties and the optimized formulation selection were explored. Additionally, the pharmacokinetic studies were scrutinized in rats. Furthermore, in Freund's adjuvant-induced arthritis, rheumatoid markers, TNF-α, IL-10, p38 MAPK, and antioxidant parameters were measured. The optimum SNVs were nano-scaled spherical vesicles (201.54 ± 9.16 nm), having reasonable entrapment efficiency (71.28 ± 2.05%), appropriate release over 8 h (89.45 ± 3.64%) and adequate permeation characteristics across the skin (402.55 ± 27.48 µg/cm²). The pharmacokinetic study disclosed ameliorated bioavailability of the optimum SNVs gel by 2.79- and 4.59-fold as compared to the oral solution as well as the traditional gel, respectively. Moreover, it elicited a significant suppression of p38 MAPK expression and also significant improvement of all other measured biomarkers. Concisely, the foregoing findings proposed that SNVs can be auspicious for augmenting FVS transdermal delivery for management of RA.

Effect of a Solid Lipid Nanoparticle Formulation on the Bioavailability of 4-(N)-Docosahexaenoyl 2', 2'-Difluorodeoxycytidine After Oral Administration

Previously, we developed a solid lipid nanoparticle (SLN) formulation of 4-(N)-docosahexaenoyl 2', 2'-difluorodeoxycytidine (DHA-dFdC), a compound with promising antitumor activity. Herein, we studied the feasibility of administering the DHA-dFdC by the oral route using the solid lipid nanoparticles (i.e., DHA-dFdC-SLNs). In simulated gastrointestinal fluids, the DHA-dFdC-SLNs did not aggregate. The release of the DHA-dFdC from the solid lipid nanoparticles in simulated gastrointestinal fluid was slow, but was slightly faster in simulated intestinal fluid than in simulated gastric fluid. In mice orally administered with DHA-dFdC-SLNs, plasma DHA-dFdC concentration vs. time curve has a T_max of ~ 1.7 h and a C_max of 17.01 μg/mL. The absolute oral bioavailability of DHA-dFdC when given as DHA-dFdC-SLNs was ~ 68% (based on AUC_{0-24 h} values), while the relative oral bioavailability DHA-dFdC (compared with DHA-dFdC in a Tween 80/ethanol-in-water solution) was 126%. Finally, in mice with pre-establish B16-F10 murine melanoma, oral DHA-dFdC-SLNs increased their survival significantly, as compared with oral administration of the DHA-dFdC solution. It is concluded that the solid lipid nanoparticle formulation increased the bioavailability of the DHA-dFdC upon oral administration, as compared with the DHA-dFdC solution.

Efficient Intestinal Digestion and On Site Tumor-Bioactivation are the Two Important Determinants for Chylomicron-Mediated Lymph-Targeting Triglyceride-Mimetic Docetaxel Oral Prodrugs

The oral absorption of chemotherapeutical drugs is restricted by poor solubility and permeability, high first-pass metabolism, and gastrointestinal toxicity. Intestinal lymphatic transport of lipophilic prodrugs is a promising strategy to improve the oral delivery efficiency of anticancer drugs via entrapment into a lipid formulation and to avoid first-pass metabolism. However, several basic principles have still not been clarified, such as intestinal digestibility and stability and on-site tumor bioactivation. Herein, triglyceride-mimetic prodrugs of docetaxel (DTX) are designed by conjugating them to the sn-2 position of triglyceride (TG) through different linkage bonds. The role of intestinal digestion in oral absorption of TG-like prodrugs is then investigated by introducing significant steric-hindrance α-substituents into the prodrugs. It is surprisingly found that poor intestinal digestion leads to an unsatisfactory bioavailability but efficient intestinal digestion of TG-like prodrugs with a less steric-hindrance linkage (DTX-S-S-TG) facilitating oral absorption. Moreover, it is found that the TG-like reduction-sensitive prodrug (DTX-S-S-TG) has good stability during intestinal transport and blood circulation, and on-demand release of docetaxel at the tumor site, leading to a significantly improved antitumor efficiency with negligible gastrointestinal toxicity. In summary, the chylomicron-mediated lymph-targeting triglyceride-mimetic oral prodrug approach provides a good foundation for the development of oral chemotherapeutical formulations.

Development of solid dispersion lipid nanoparticles for improving skin delivery

Applications of poorly water-soluble drugs in skin delivery pose several challenges to pharmaceutical formulation. This research originally developed solid lipid nanoparticles (SLNs) packaging a modified core of a solid dispersion (SD) in the lipid matrix to modulate the skin release patterns. Curcumin (CUR) was selected as the poorly water-soluble drug applied in the formulation. The designed system, so-called solid dispersion lipid nanoparticles (SD-SLNs), was fabricated by incorporating a solidifying SD or a non-solidifying SD into the core of the SLNs by ultrasonication. Release studies illustrated an important enhancement in the drug release of the proposed system compared to pure CUR and SLN formulations without the presence of SD as the modified core, which indicated the positive effect of the combined colloidal method of SD and SLNs. The physicochemical properties of the SD-SLN systems were also elucidated using powder X-ray diffraction, Fourier transform infrared spectroscopy, and particle size analysis. The drug was found to change to an amorphous state without any molecular interactions along with a marked particle size reduction. This work demonstrated the strong potential of applying a novel SD-SLN system for the skin delivery of a drug with poor water solubility.

A solid lipid nanoparticle formulation of 4-(N)-docosahexaenoyl 2', 2'-difluorodeoxycytidine with increased solubility, stability, and antitumor activity

Previously, we synthesized 4-(N)-docosahexaenoyl 2', 2'-difluorodeoxycytidine (DHA-dFdC), a novel lipophilic compound with a potent, broad-spectrum antitumor activity. Herein, we report a solid lipid nanoparticle (SLN) formulation of DHA-dFdC with improved apparent aqueous solubility, chemical stability, as well as efficacy in a mouse model. The SLNs were prepared from lecithin/glycerol monostearate-in-water emulsions emulsified with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) and Tween 20. The resultant DHA-dFdC-SLNs were 102.2 ± 7.3 nm in diameter and increased the apparent solubility of DHA-dFdC in water to at least 5.2 mg/mL, more than 200-fold higher than its intrinsic water solubility. DHA-dFdC in a lyophilized powder of DHA-dFdC-SLNs was significantly more stable than the waxy solid of pure DHA-dFdC. DHA-dFdC-SLNs also showed an increased cytotoxicity against certain tumor cells than DHA-dFdC. The plasma concentration of DHA-dFdC in mice intravenously injected with DHA-dFdC-SLNs in dispersion followed a bi-exponential model, with a half-life of ~44 h. In mice bearing B16-F10 murine melanoma, DHA-dFdC-SLNs were significantly more effective than DHA-dFdC in controlling the tumor growth. In addition, histology evaluation revealed a high level of apoptosis and tumor encapsulation in tumors in mice treated with DHA-dFdC-SLNs. DHA-dFdC-SLNs represents a new DHA-dFdC formulation with improved antitumor activity.

Tripling the Bioavailability of Rosuvastatin Calcium Through Development and Optimization of an In-Situ Forming Nanovesicular System

In situ forming nanovesicular systems (IFNs) were prepared and optimized to improve Rosuvastatin calcium (RC) oral bioavailability through increasing its solubility and dissolution rate. The IFN was composed of Tween^® 80 (T80), cetyl alcohol (CA), in addition to mannitol or Aerosil 200. A single simple step was adopted for preparation, then the prepared formulations were investigated by analyzing their particle size (PS), polydispersity index (PDI), Zeta potential (ZP), entrapment efficiency (EE), and flowability properties. D-optimal design was applied to choose the optimized formulations. The maximum desirability values were 0.754 and 0.478 for the optimized formulations containing 0.05 g CA, 0.18 g T80, and 0.5 g mannitol (OFM) or Aerosil (OFA), respectively. In vitro drug release from the optimized formulations showed a significantly faster dissolution rate when compared to the market product. In vivo performance of the optimized formulations in rabbits was investigated after filling them into enteric-coated capsules. Ultimately, OFA formulation achieved a 3 times increase in RC oral bioavailability in comparison with the market product, supporting the hypothesis of considering IFNs as promising nanocarriers able to boost the bioavailability of BCS class II drugs.

LC478, a Novel Di-Substituted Adamantyl Derivative, Enhances the Oral Bioavailability of Docetaxel in Rats

P-glycoprotein (P-gp)-mediated efflux of docetaxel in the gastrointestinal tract mainly impedes its oral chemotherapy. Recently, LC478, a novel di-substituted adamantyl derivative, was identified as a non-cytotoxic P-gp inhibitor in vitro. Here, we assessed whether LC478 enhances the oral bioavailability of docetaxel in vitro and in vivo. LC478 inhibited P-gp mediated efflux of docetaxel in Caco-2 cells. In addition, 100 mg/kg of LC478 increased intestinal absorption of docetaxel, which led to an increase in area under plasma concentration-time curve (AUC) and absolute bioavailability of docetaxel in rats. According to U.S. FDA criteria (I, an inhibitor concentration in vivo tissue)/(IC₅₀, inhibitory constant in vitro) >10 determines P-gp inhibition between in vitro and in vivo. The values 15.6–20.5, from (LC478 concentration in intestine, 9.37–12.3 μM)/(IC₅₀ of LC478 on P-gp inhibition in Caco-2 cell, 0.601 μM) suggested that 100 mg/kg of LC478 sufficiently inhibited P-gp to enhance oral absorption of docetaxel. Moreover, LC478 inhibited P-gp mediated efflux of docetaxel in the ussing chamber studies using rat small intestines. Our study demonstrated that the feasibility of LC478 as an ideal enhancer of docetaxel bioavailability by P-gp inhibition in dose (concentration)-dependent manners.

Potential of Lipid Nanoparticles (SLNs and NLCs) in Enhancing Oral Bioavailability of Drugs with Poor Intestinal Permeability

Lipid-based drug delivery systems has become a popular choice for oral delivery of lipophilic drugs with dissolution rate limited oral absorption. Lipids are known to enhance oral bioavailability of poorly water-soluble drugs in multiple ways like facilitating dissolution as micellar solution, enhancing the lymphatic uptake and acting as inhibitors of efflux transporters. Lipid nanoparticles are matrix type lipid-based carrier systems which can effectively encapsulate both lipophilic and hydrophilic drugs. Lipid nanoparticles namely solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) are versatile drug delivery system and can be used for multiple routes of delivery like parenteral, topical, ocular, transdermal, and oral. Lipid nanoparticles are particularly attractive vehicles for peroral delivery of drugs with oral bioavailability problems as they are composed of lipid excipients which are cheap, easily available, and non-toxic; manufacturing technique is simple and readily scalable for large-scale production; the formulations provide controlled release of active components and have no stability issue. A large number of drugs have been incorporated into lipid nanoparticles with the objective of overcoming their poor oral bioavailability. This review tries to assess the potential of lipid nanoparticles for enhancing the oral bioavailability of drugs with permeability limited oral absorption such as drugs belonging to class IV of Biopharmaceutic Classification System (BCS) and protein and peptide drugs and also discusses the mechanism behind the bioavailability enhancement and safety issues related to such delivery systems.

Use of Lipid Nanocarriers to Improve Oral Delivery of Vitamins

The chemical environment and enzymes in the gastrointestinal (GI) membrane limit the oral absorption of some vitamins. The GI epithelium also contributes to the poor permeability of numerous antioxidant agents. Thus, lipophilic vitamins do not readily dissolve in the GI tract, and therefore they have low bioavailability. Nanomedicine has the potential to improve the delivery efficiency of oral vitamins. In particular, the use of lipid nanocarriers for certain vitamins that are administered orally can provide improved solubility, chemical stability, epithelium permeability and bioavailability, half-life, nidus targeting, and fewer adverse effects. These lipid nanocarriers include self-emulsifying drug delivery systems (SEDDSs), nanoemulsions, microemulsions, solid lipid nanoparticles (SLNs), and nanostructured lipid carriers (NLCs). The use of nontoxic excipients and sophisticated material engineering of lipid nanosystems allows for control of the physicochemical properties of the nanoparticles and improved GI permeation via mucosal or lymphatic transport. In this review, we highlight recent progress in the development of lipid nanocarriers for vitamin delivery. In addition, the same lipid nanocarriers used for vitamins may also be effective as carriers of vitamin derivatives, and therefore enhance their oral bioavailability. One example is the incorporation of d-α-tocopheryl polyethylene glycol succinate (TPGS) as the emulsifier in lipid nanocarriers to increase the solubility and inhibit P-glycoprotein (P-gp) efflux. We also survey the concepts and discuss the mechanisms of nanomedical techniques that are used to develop vitamin-loaded nanocarriers.

Nanodelivery systems and stabilized solid-drug nanoparticles for orally administered medicine: current landscape

The use of nanoparticles as a means of targeted delivery of therapeutics and imaging agents could greatly enhance the transport of biologically active contents to specific target tissues, while avoiding or reducing potentially undesired side effects. Generally speaking, the oral route of administration is associated with good patient compliance, as it is convenient, economical, noninvasive, and does not require special training. Here, we review the progress of the utilization of nanodelivery-system carriers or stabilized solid-drug nanoparticles following oral administration, with particular attention on toxicological data. Mechanisms of cytotoxicity are discussed and the problem of extrapolating knowledge to human scenarios highlighted. Additionally, issues associated with administration of drugs via the oral route are underlined, while strategies utilized to overcome these are highlighted. This review aims to offer a balanced overview of strategies currently being used in the application of nanosize constructs for oral medical applications.

Novel in situ gelling vaginal sponges of sildenafil citrate-based cubosomes for uterine targeting

Sildenafil citrate (SIL), a type 5-specific phosphodiesterase inhibitor, demonstrates valuable results in the management of infertility in women; however, the absence of vaginal dosage form in addition to the associated oral adverse effects minimize its clinical performance. The present study is concerned with SIL uterine targeting following intravaginal administration via optimization of cubosomal in situ gelling sponges (CIS). An emulsification method was employed for preparation of cubosomal dispersions incorporating glyceryl monooleate as a lipid phase and poloxamer 407 as a surfactant with or without polyvinyl alcohol as a stabilizer. Cubosomes were estimated regarding entrapment efficiency (EE%), particle size, and in vitro drug release. Chitosan (2% w/w) was incorporated into the optimum formulation and then lyophilized into small sponges. For the CIS, in vivo histopathological and pharmacokinetic studies were conducted on female Wistar rats and compared with intravaginal free SIL sponges (FIS) and oral SIL solution. SIL-loaded cubosomes showed EE% ranging between 32.15 and 72.01%, particle size in the range of 150.81–446.02 nm and sustained drug release over 8 h. Histopathological study revealed a significant enlargement in endometrial thickness with congestion and dilatation of endometrial blood vessels in intravaginal CIS compared to intravaginal FIS and oral-treated groups. The pharmacokinetic study demonstrated higher AUC_0–∞ and C_max with oral administration compared to intravaginal CIS or intravaginal FIS indicating potential involvement of first uterine pass effect after intravaginal administration. Finally, intravaginal CIS could be considered as a promising platform for SIL uterine targeting with minimized systemic exposure and side effects.

Exploring Peyer's Patch Uptake as a Strategy for Targeted Lung Delivery of Polymeric Rifampicin Nanoparticles

Uptake of nanoparticles through Peyer's Patches following oral administration could enable translocation through lymph to lymphatic organs like the lungs. An important consideration, however, is nanosize and particle hydrophobicity. Furthermore, as delivering the nanoparticles to the intestine where the Peyer's Patches are localized is important, their intact and rapid transit through the stomach into the intestine is highly desirable. We report hydrophobization of mucoadhesive Rifampicin-GantrezAN-119 nanoparticles (GzNP) using a hydrophobic polymer, ethyl cellulose (EC), with the objectives of augmenting Peyer's Patch uptake due to enhanced hydrophobicity and increased intestinal localization as a result of decreased mucoadhesion. RIF-Gantrez-EC nanoparticles (ECGzNP2) exhibited >13% RIF loading and an average particle size of 400-450 nm, which is appropriate for translation through lymph following Peyer's Patch uptake. Higher contact angle (67.3 ± 3.5° vs 30.3 ± 2.1°) and lower mucoadhesion (30.7 ± 4.8 g vs 87.0 ± 3.0 g) of ECGzNP2 over GzNP confirmed hydrophobization and lower mucoadhesion. Fluorescence photomicrographs of intraduodenally administered coumarin-labeled RIF-NP in rats demonstrated higher Peyer's Patch uptake with ECGzNP2, while the increased lung/plasma RIF ratio signified lymph mediated lung targeting. The gastrointestinal transit study in rats, which revealed a significantly higher intestine-to-stomach accumulation ratio with ECGzNP2 (3.4) compared to GzNP (1.0) [ p < 0.05], confirmed availability of the NP in the intestine for Peyer's Patch uptake. Such uptake enabled 182.4 ± 22.6% increase in relative bioavailability, a ∼2-fold higher plasma AUC/MIC ratio and significantly higher lung concentration with ECGzNP2, thereby proposing better efficacy. A significantly higher lung/liver ratio with ECGzNP2 also suggested lower hepatic exposure. The repeated dose 28-day oral toxicity study demonstrated the safety of the nanocarrier and reduced hepatotoxicity with ECGzNP2 compared to RIF. We hereby demonstrate uptake of orally administered NP through Peyer's Patches as a feasible strategy for lung targeting.

Enhanced Lymphatic Uptake of Leflunomide Loaded Nanolipid Carrier via Chylomicron Formation for the Treatment of Rheumatoid Arthritis

Purpose: The current study aims the lymphatic delivery of leflunomide loaded nanostructured lipid carriers (LNLC) for the treatment of rheumatoid arthritis, mainly focussed to enhance the lymphatic delivery via chylomicron formation, improved bioavailability and reduced systemic toxicity.

Methods: Melt emulsification ultra-sonication method was used to formulate the nanostructured lipid carrier (NLC) containing leflunomide. Four batches were prepared by using various concentration of surfactants (tween 80 and poloxmer 188) and lipid mixtures (stearic acid and oleic acid). All the formulations were studied for various physiochemical properties

Results: The formulation with increased concentration of lipid and surfactants showed highest entrapment efficiency (93.96 ± 0.47%) and better drug release (90.35%) at the end of 48 hrs. In vivo tests were carried out to determine the antiarthritic potential of the formulation in Sprague-dawley rats for a duration of 30d. The effect was evaluated by measuring the reduction in knee thickness. LNLC showed a marked reduction in inflammation compared to standard drug. Intestinal lymphatic uptake studies of LNLC were performed by intraduodenal administration and compared with leflunomide drug solution. The mesenteric lymph node was analysed by HPLC method and the concentration of drug was estimated. It showed that LNLC having highest uptake (40.34μg/ml) when compared with leflunomide drug solution (10.04μg/ml). Radiographic analysis and histopathological studies showed the formation of healthy cartilage after treatment period.

Conclusion: The results suggested that LNLC has the potential to reduce the systemic toxicities associated with conventional therapy along with improved efficacy in the treatment of rheumatoid arthritis.

Advancements in the oral delivery of Docetaxel: challenges, current state-of-the-art and future trends

The oral delivery of cancer chemotherapeutic drugs is challenging due to low bioavailability, gastrointestinal side effects, first-pass metabolism and P-glycoprotein efflux pumps. Thus, chemotherapeutic drugs, including Docetaxel, are administered via an intravenous route, which poses many disadvantages of its own. Recent advances in pharmaceutical research have focused on designing new and efficient drug delivery systems for site-specific targeting, thus leading to improved bioavailability and pharmacokinetics. A decent number of studies have been reported for the safe and effective oral delivery of Docetaxel. These nanocarriers, including liposomes, polymeric nanoparticles, metallic nanoparticles, hybrid nanoparticles, dendrimers and so on, have shown promising results in research papers and clinical trials. The present article comprehensively reviews the research efforts made so far in designing various advancements in the oral delivery of Docetaxel. Different strategies to improve oral bioavailability, prevent first-pass metabolism and inhibition of efflux pumping leading to improved pharmacokinetics and anticancer activity are discussed. The final portion of this review article presents key issues such as safety of nanomaterials, regulatory approval and future trends in nanomedicine research.

Development of a Rapid and Precise Reversed-phase High-performance Liquid Chromatography Method for Analysis of Docetaxel in Rat Plasma: Application in Single-dose Pharmacokinetic Studies of Folate-targeted Micelles Containing Docetaxel

Background:

A simple and sensitive reversed-phase high-performance liquid chromatography (HPLC) method based on liquid-liquid extraction was established and validated for determination of docetaxel (DTX) in plasma of rat.

Materials and Methods:

Samples were spiked with paclitaxel as the internal standard and the chromatographic separation was carried out using C18 HPLC column. The mobile phase consisted of a mixture of acetonitrile/water with the ratio of 60/40 v/v. The ultraviolet detector was operated at 230 nm, and the flow rate of mobile phase was 1 ml/min. The method was validated for linearity, precision, accuracy, recovery, and limit of quantification (LOQ). Then the method was applied to quantify DTX in the rat plasma after intravenous (IV) administration of the self-assembled micelles of folate-targeted Synpronic F127/cholesterol (FA-PF127-Chol) loaded with DTX and Taxotere^® as the reference marketed solution of DTX. The blood samples were taken from the ophthalmic vein at predetermined time intervals after treatment.

Results:

Calibration curve was linear between the concentration ranges of 0.1–7.5 μg/ml with the relative standard deviation % and evaluating error % ranged from 2.263 to 15.53 and −12.75 to 12.7 for intra- and inter-day validity, respectively. The mean recovery of the drug after plasma extraction was 95.67 ± 0.99% for the concentration of 1 μg/ml. The LOQ and the limit of detection for DTX in serum were 100 ng/ml and 30 ng/ml, respectively.

Conclusions:

The results indicated that the developed method could be adopted for pharmacokinetic studies of DTX-loaded FA-PF127-Chol micelles and Taxotere^® in rat.

Recent Advances in the Application of Vitamin E TPGS for Drug Delivery

D-ɑ-tocopheryl polyethylene glycol succinate (Vitamin E TPGS or TPGS) has been approved by FDA as a safe adjuvant and widely used in drug delivery systems. The biological and physicochemical properties of TPGS provide multiple advantages for its applications in drug delivery like high biocompatibility, enhancement of drug solubility, improvement of drug permeation and selective antitumor activity. Notably, TPGS can inhibit the activity of ATP dependent P-glycoprotein and act as a potent excipient for overcoming multi-drug resistance (MDR) in tumor. In this review, we aim to discuss the recent advances of TPGS in drug delivery including TPGS based prodrugs, nitric oxide donor and polymers, and unmodified TPGS based formulations. These potential applications are focused on enhancing delivery efficiency as well as the therapeutic effect of agents, especially on overcoming MDR of tumors. It also demonstrates that the clinical translation of TPGS based nanomedicines is still faced with many challenges, which requires more detailed study on TPGS properties and based delivery system in the future.

Recent developments in d-α-tocopheryl polyethylene glycol-succinate-based nanomedicine for cancer therapy

Cancer remains an obstacle to be surmounted by humans. As an FDA-approved biocompatible drug excipient, d-α-tocopheryl polyethylene glycol succinate (TPGS) has been widely applied in drug delivery system (DDS). Along with in-depth analyses of TPGS-based DDS, increasingly attractive results have revealed that TPGS is able to act not only as a simple drug carrier but also as an assistant molecule with various bio-functions to improve anticancer efficacy. In this review, recent advances in TPGS-based DDS are summarized. TPGS can inhibit P-glycoprotein, enhance drug absorption, induce mitochondrial-associated apoptosis or other apoptotic pathways, promote drug penetration and tumor accumulation, and even inhibit tumor metastasis. As a result, many formulations, by using original TPGS, TPGS-drug conjugates or TPGS copolymers, were prepared, and as expected, an enhanced therapeutic effect was achieved in different tumor models, especially in multidrug resistant and metastatic tumors. Although the mechanisms by which TPGS participates in such functions are not yet very clear, considering its effectiveness in tumor treatment, TPGS-based DDS appears to be one of the best candidates for future clinical applications.

Strategies for improving drug delivery: nanocarriers and microenvironmental priming

INTRODUCTION

The ultimate goal in the field of drug delivery is to exclusively direct therapeutic agents to pathological tissues in order to increase therapeutic efficacy and eliminate side effects. This goal is challenging due to multiple transport obstacles in the body. Strategies that improve drug transport exploit differences in the characteristics of normal and pathological tissues. Within the field of oncology, these concepts have laid the groundwork for a new discipline termed transport oncophysics. Areas covered: Efforts to improve drug biodistribution have mainly focused on nanocarriers that enable preferential accumulation of drugs in diseased tissues. A less common approach to enhance drug transport involves priming strategies that modulate the biological environment in ways that favor localized drug delivery. This review discusses a variety of priming and nanoparticle design strategies that have been used for drug delivery. Expert opinion: Combinations of priming agents and nanocarriers are likely to yield optimal drug distribution profiles. Although priming strategies have yet to be widely implemented, they represent promising solutions for overcoming biological transport barriers. In fact, such strategies are not restricted to priming the tumor microenvironment but can also be directed toward healthy tissue in order to reduce nanoparticle uptake.

Self-Assembled Lipid Nanoparticles for Oral Delivery of Heparin-Coated Iron Oxide Nanoparticles for Theranostic Purposes

Recently, solid lipid nanoparticles (SLNs) have attracted increasing attention owing to their potential as an oral delivery system, promoting intestinal absorption in the lymphatic circulation which plays a role in disseminating metastatic cancer cells and infectious agents throughout the body. SLN features can be exploited for the oral delivery of theranostics. Therefore, the aim of this work was to design and characterise self-assembled lipid nanoparticles (SALNs) to encapsulate and stabilise iron oxide nanoparticles non-covalently coated with heparin (Fe@hepa) as a model of a theranostic tool. SALNs were characterised for physico-chemical properties (particle size, surface charge, encapsulation efficiency, in vitro stability, and heparin leakage), as well as in vitro cytotoxicity by methyl thiazole tetrazolium (MTT) assay and cell internalisation in CaCo-2, a cell line model used as an indirect indication of intestinal lymphatic absorption. SALNs of about 180 nm, which are stable in suspension and have a high encapsulation efficiency (>90%) were obtained. SALNs were able to stabilise the heparin coating of Fe@hepa, which are typically unstable in physiological environments. Moreover, SALNs–Fe@hepa showed no cytotoxicity, although their ability to be internalised into CaCo-2 cells was highlighted by confocal microscopy analysis. Therefore, the results indicated that SALNs can be considered as a promising tool to orally deliver theranostic Fe@hepa into the lymphatic circulation, although further in vivo studies are needed to comprehend further potential applications.

Docetaxel-Loaded Nanoparticles Assembled from β-Cyclodextrin/Calixarene Giant Surfactants: Physicochemical Properties and Cytotoxic Effect in Prostate Cancer and Glioblastoma Cells

Giant amphiphiles encompassing a hydrophilic β-cyclodextrin (βCD) component and a hydrophobic calix[4]arene (CA₄) module undergo self-assembly in aqueous media to afford core-shell nanospheres or nanocapsules, depending on the nanoprecipitation protocol, with high docetaxel (DTX) loading capacity. The blank and loaded nanoparticles have been fully characterized by dynamic light scattering (DLS), ζ-potential measurements and cryo-transmission electron microscopy (cryo-TEM). The data are compatible with the distribution of the drug between the nanoparticle core and the shell, where it is probably anchored by inclusion of the DTX aromatic moieties in βCD cavities. Indeed, the release kinetics profiles evidenced an initial fast release of the drug, which likely accounts for the fraction hosted on the surface, followed by a slow and sustained release rate, corresponding to diffusion of DTX in the core, which can be finely tuned by modification of the giant amphiphile chemical structure. The ability of the docetaxel-loaded nanoparticles to induce cellular death in different prostate (human LnCap and PC3) and glioblastoma (human U87 and rat C6) cells was also explored. Giant amphiphile-based DTX formulations surpassing or matching the antitumoral activity of the free DTX formulation were identified in all cases with no need to employ any organic co-solvent, thus overcoming the DTX water solubility problems. Moreover, the presence of the βCD shell at the surface of the assemblies is intended to impart stealth properties against serum proteins while permitting nanoparticle surface decoration by supramolecular approaches, paving the way for a new generation of molecularly well-defined antitumoral drug delivery systems with improved specificity and efficiency. Altogether, the results provide a proof of concept of the suitability of the approach based on βCD-CA₄ giant amphiphiles to access DTX carriers with tunable properties.

Hesperetin Liposomes for Cancer Therapy

Hesperetin is a compound from citrus fruit that has previously been found to exert anticancer activity through a variety of mechanisms. However, the application of hesperetin to cancer therapy has been hampered by its hydrophobicity, necessitating the use of toxic solubilizing agents. Here, we have developed the first liposome-based delivery system for hesperetin. Liposomes were fabricated using the thin-layer evaporation technique and physical and pharmacological parameters were measured. The liposomes remained stable for prolonged periods of time in serum and under storage conditions, and displayed anticancer efficacy in both H441 lung cancer cells and MDA-MB-231 breast cancer cells. Furthermore, the anticancer activity was not impaired in cells expressing the multidrug resistance protein 1 (MDR-1). In conclusion, the encapsulation of hesperetin in liposomes does not interfere with therapeutic efficacy and provides a biocompatible alternative to toxic solubilizing agents, thereby enabling future clinical use of this compound for cancer therapy.

Preparation and Optimization OF Palm-Based Lipid Nanoparticles Loaded with Griseofulvin

Palm-based lipid nanoparticle formulation loaded with griseofulvin was prepared by solvent-free hot homogenization method. The griseofulvin loaded lipid nanoparticles were prepared via stages of optimisation, by altering the high pressure homogenisation (HPH) parameters, screening on palm-based lipids and Tween series surfactants and selection of lipid to surfactant ratios. A HPLC method has been validated for the drug loading capacity study. The optimum HPH parameter was determined to be 1500 bar with 5 cycles and among the palm-based lipid materials; Lipid C (triglycerides) was selected for the preparation of lipid nanoparticles. Tween 80 was chosen from the Tween series surfactants for its highest saturated solubility of griseofulvin at 53.1 ± 2.16 µg/mL. The optimum formulation of the griseofulvin loaded lipid nanoparticles demonstrated nano-range of particle size (179.8 nm) with intermediate distribution index (PDI) of 0.306, zeta potential of -27.9 mV and drug loading of 0.77%. The formulation was stable upon storage for 1 month at room temperature (25 ^°C) and 45 ^°C with consistent drug loading capacity.

Lipid-associated oral delivery: Mechanisms and analysis of oral absorption enhancement

The majority of newly discovered oral drugs are poorly water soluble, and co-administration with lipids has proven effective in significantly enhancing bioavailability of some compounds with low aqueous solubility. Yet, lipid-based delivery technologies have not been widely employed in commercial oral products. Lipids can impact drug transport and fate in the gastrointestinal (GI) tract through multiple mechanisms including enhancement of solubility and dissolution kinetics, enhancement of permeation through the intestinal mucosa, and triggering drug precipitation upon lipid emulsion depletion (e.g., by digestion). The effect of lipids on drug absorption is currently not quantitatively predictable, in part due to the multiple complex dynamic processes that can be impacted by lipids. Quantitative mechanistic analysis of the processes significant to lipid system function and overall impact on drug absorption can aid in the understanding of drug-lipid interactions in the GI tract and exploitation of such interactions to achieve optimal lipid-based drug delivery. In this review, we discuss the impact of co-delivered lipids and lipid digestion on drug dissolution, partitioning, and absorption in the context of the experimental tools and associated kinetic expressions used to study and model these processes. The potential benefit of a systems-based consideration of the concurrent multiple dynamic processes occurring upon co-dosing lipids and drugs to predict the impact of lipids on drug absorption and enable rational design of lipid-based delivery systems is presented.

Surface Modified Multifunctional and Stimuli Responsive Nanoparticles for Drug Targeting: Current Status and Uses

Nanocarriers, due to their unique features, are of increased interest among researchers working with pharmaceutical formulations. Polymeric nanoparticles and nanocapsules, involving non-toxic biodegradable polymers, liposomes, solid lipid nanoparticles, and inorganic-organic nanomaterials, are among the most used carriers for drugs for a broad spectrum of targeted diseases. In fact, oral, injectable, transdermal-dermal and ocular formulations mainly consist of the aforementioned nanomaterials demonstrating promising characteristics such as long circulation, specific targeting, high drug loading capacity, enhanced intracellular penetration, and so on. Over the last decade, huge advances in the development of novel, safer and less toxic nanocarriers with amended properties have been made. In addition, multifunctional nanocarriers combining chemical substances, vitamins and peptides via coupling chemistry, inorganic particles coated by biocompatible materials seem to play a key role considering that functionalization can enhance characteristics such as biocompatibility, targetability, environmental friendliness, and intracellular penetration while also have limited side effects. This review aims to summarize the "state of the art" of drug delivery carriers in nanosize, paying attention to their surface functionalization with ligands and other small or polymeric compounds so as to upgrade active and passive targeting, different release patterns as well as cell targeting and stimuli responsibility. Lastly, future aspects and potential uses of nanoparticulated drug systems are outlined.

Developments in Methods for Measuring the Intestinal Absorption of Nanoparticle-Bound Drugs

With the rapid development of nanotechnology, novel drug delivery systems comprising orally administered nanoparticles (NPs) have been paid increasing attention in recent years. The bioavailability of orally administered drugs has significant influence on drug efficacy and therapeutic dosage, and it is therefore imperative that the intestinal absorption of oral NPs be investigated. This review examines the various literature on the oral absorption of polymeric NPs, and provides an overview of the intestinal absorption models that have been developed for the study of oral nanoparticles. Three major categories of models including a total of eight measurement methods are described in detail (in vitro: dialysis bag, rat gut sac, Ussing chamber, cell culture model; in situ: intestinal perfusion, intestinal loops, intestinal vascular cannulation; in vivo: the blood/urine drug concentration method), and the advantages and disadvantages of each method are contrasted and elucidated. In general, in vitro and in situ methods are relatively convenient but lack accuracy, while the in vivo method is troublesome but can provide a true reflection of drug absorption in vivo. This review summarizes the development of intestinal absorption experiments in recent years and provides a reference for the systematic study of the intestinal absorption of nanoparticle-bound drugs.

Nanoparticles for oral delivery: Design, evaluation and state-of-the-art

The oral route is a preferred method of drug administration, though achieving effective drug delivery and minimizing off-target side effects is often challenging. Formulation into nanoparticles can improve drug stability in the harsh gastrointestinal (GI) tract environment, providing opportunities for targeting specific sites in the GI tract, increasing drug solubility and bioavailability, and providing sustained release in the GI tract. However, the unique and diverse physiology throughout the GI tract, including wide variation in pH, mucus that varies in thickness and structure, numerous cell types, and various physiological functions are both a barrier to effective delivery and an opportunity for nanoparticle design. Here, nanoparticle design aspects to improve delivery to particular sites in the GI tract are discussed. We then review new methods for evaluating oral nanoparticle formulations, including a short commentary on data interpretation and translation. Finally, the state-of-the-art in preclinical targeted nanoparticle design is reviewed.

Design and statistical modeling of mannose-decorated dapsone-containing nanoparticles as a strategy of targeting intestinal M-cells

The aim of the present work was to develop and optimize surface-functionalized solid lipid nanoparticles (SLNs) for improvement of the therapeutic index of dapsone (DAP), with the application of a design of experiments. The formulation was designed to target intestinal microfold (M-cells) as a strategy to increase internalization of the drug by the infected macrophages. DAP-loaded SLNs and mannosylated SLNs (M-SLNs) were successfully developed by hot ultrasonication method employing a three-level, three-factor Box–Behnken design, after the preformulation study was carried out with different lipids. All the formulations were systematically characterized regarding their diameter, polydispersity index (PDI), zeta potential (ZP), entrapment efficiency, and loading capacity. They were also subjected to morphological studies using transmission electron microscopy, in vitro release study, infrared analysis (Fourier transform infrared spectroscopy), calorimetry studies (differential scanning calorimetry), and stability studies. The diameter of SLNs, SLN-DAP, M-SLNs, and M-SLN-DAP was approximately 300 nm and the obtained PDI was <0.2, confirming uniform populations. Entrapment efficiency and loading capacity were approximately 50% and 12%, respectively. Transmission electron microscopy showed spherical shape and nonaggregated nanoparticles. Fourier transform infrared spectroscopy was used to confirm the success of mannose coating process though Schiff’s base formation. The variation of the ZP between uncoated (approximately −30 mV) and mannosylated formulations (approximately +60 mV) also confirmed the successful coating process. A decrease in the enthalpy and broadening of the lipid melting peaks of the differential scanning calorimetry thermograms are consistent with the nanostructure of the SLNs. Moreover, the drug release was pH-sensitive, with a faster drug release at acidic pH than at neutral pH. Storage stability for the formulations for at least 8 weeks is expected, since they maintain the original characteristics of diameter, PDI, and ZP. These results pose a strong argument that the developed formulations can be explored as a promising carrier for treating leprosy with an innovative approach to target DAP directly to M-cells.

Comparing in vivo biodistribution with radiolabeling and Franz cell permeation assay to validate the efficacy of both methodologies in the evaluation of nanoemulsions: a safety approach

The Franz cells permeation assay has been performed for over 25 years. However, the advent of nanotechnology created a whole new world, especially with regard to topical products. In this new global scenario an increasing number of nanostructure-based delivery systems (NDSs) have emerged and a global warning relating to the safety of these NDSs is arising. This work studied the efficacy of the Franz cells assay, comparing it with the radiolabeling biodistribution test. For this purpose a formulation of sunscreen based on an NDS was developed and characterized. The results demonstrated both that the NDS did not present in vitro cytotoxicity and that the radiolabeling biodistribution test is more precise for the evaluation of NDS cosmetics than the Franz cells assay, since it detected the permeation of the NDS at a picogram order. Due to this fact, and considering all the concerns related to NDSs and nanoparticles in general, more precise methods must be used in order to guarantee the safe use of these new classes of products.

Comparative study on solid self-nanoemulsifying drug delivery and solid dispersion system for enhanced solubility and bioavailability of ezetimibe

Background

The objective of this study was to compare the physicochemical characteristics, solubility, dissolution, and oral bioavailability of an ezetimibe-loaded solid self-nanoemulsifying drug delivery system (SNEDDS), surface modified solid dispersion (SMSD), and solvent evaporated solid dispersion (SESD) to identify the best drug delivery system with the highest oral bioavailability.

Methods

For the liquid SNEDDS formulation, Capryol 90, Cremophor EL, and Tween 80 were selected as the oil, surfactant, and cosurfactant, respectively. The nanoemulsion-forming region was sketched using a pseudoternary phase diagram on the basis of reduced emulsion size. The optimized liquid SNEDDS was converted to solid SNEDDS by spray drying with silicon dioxide. Furthermore, SMSDs were prepared using the spray drying technique with various amounts of hydroxypropylcellulose and Tween 80, optimized on the basis of their drug solubility. The SESD formulation was prepared with the same composition of optimized SMSD. The aqueous solubility, dissolution, physicochemical properties, and pharmacokinetics of all of the formulations were investigated and compared with the drug powder.

Results

The drug existed in the crystalline form in SMSD, but was changed into an amorphous form in SNEDDS and SESD, giving particle sizes of approximately 24, 6, and 11 µm, respectively. All of these formulations significantly improved the aqueous solubility and dissolution in the order of solid SNEDDS ≥ SESD > SMSD, and showed a total higher plasma concentration than did the drug powder. Moreover, SESD gave a higher area under the drug concentration time curve from zero to infinity than did SNEDDS and SMSD, even if they were not significantly different, suggesting more improved oral bioavailability.

Conclusion

Among the various formulations tested in this study, the SESD system would be strongly recommended as a drug delivery system for the oral administration of ezetimibe with poor water solubility.

A gastrointestinal transit study on amphotericin B-loaded solid lipid nanoparticles in rats

The gastrointestinal (GI) transit behavior of and absorption from an amphotericin B (AmB) solid lipid nanoformulation (SLN) in rats was investigated. We aimed to estimate the gastric emptying time (GET) and cecal arrival time (CAT) of AmB SLN in rats as animal models. From these two parameters, an insight on the absorption window of AmB was ascertained. Three types of SLNs, AmB, paracetamol (PAR), and sulfasalazine (SSZ), were similarly formulated using beeswax/theobroma oil composite as the lipid matrix and characterized with regard to size, viscosity, density, migration propensity within agarose gel, in vitro drug release, morphology, gastrointestinal transit, and in vivo absorption. The GET and CAT were estimated indirectly using marker drugs: PAR and sulfapyridine (SP). All three types of SLNs exhibited identical properties with regard to z-average, viscosity, relative density, and propensity to migrate. PAR was absorbed rapidly from the small intestine following emptying of the SLNs giving the T50E (time for 50% absorption of PAR) to be 1.6 h. SP was absorbed after release and microbial degradation of SSZ from SLN in the colon with a lag time of 2 h post-administration, serving as the estimated cecal arrival time of the SLNs. AmB within SLN was favorably absorbed from the small intestine, albeit slowly.

Soluplus®/TPGS-based solid dispersions prepared by hot-melt extrusion equipped with twin-screw systems for enhancing oral bioavailability of valsartan

BACKGROUND

Soluplus(®) (SP) and D-alpha-tocopherol polyethylene glycol 1000 succinate (TPGS)-based solid dispersion (SD) formulations were developed by hot-melt extrusion (HME) to improve oral bioavailability of valsartan (VST).

METHODS

HME process with twin-screw configuration for generating a high shear stress was used to prepare VST SD formulations. The thermodynamic state of the drug and its dispersion in the polymers were evaluated by solid-state studies, including Fourier-transform infrared, X-ray diffraction, and differential scanning calorimetry. Drug release from the SD formulations was assessed at pH values of 1.2, 4.0, and 6.8. Pharmacokinetic study was performed in rats to estimate the oral absorption of VST.

RESULTS

HME with a high shear rate produced by the twin-screw system was successfully applied to prepare VST-loaded SD formulations. Drug amorphization and its molecular dispersion in the polymer matrix were verified by several solid-state studies. Drug release from SD formulations was improved, compared to the pure drug, particularly at pH 6.8. Oral absorption of drug in rats was also enhanced in SP and TPGS-based SD groups compared to that in the pure drug group.

CONCLUSION

SP and TPGS-based SDs, prepared by the HME process, could be used to improve aqueous solubility, dissolution, and oral absorption of poorly water-soluble drugs.

Angelica gigas Nakai and Soluplus-Based Solid Formulations Prepared by Hot-Melting Extrusion: Oral Absorption Enhancing and Memory Ameliorating Effects

Oral solid formulations based on Angelica gigas Nakai (AGN) and Soluplus were prepared by the hot-melting extrusion (HME) method. AGN was pulverized into coarse and ultrafine particles, and their particle size and morphology were investigated. Ultrafine AGN particles were used in the HME process with high shear to produce AGN-based formulations. In simulated gastrointestinal fluids (pH 1.2 and pH 6.8) and water, significantly higher amounts of the major active components of AGN, decursin (D) and decursinol angelate (DA), were extracted from the HME-processed AGN/Soluplus (F8) group than the AGN EtOH extract (ext) group (p < 0.05). Based on an in vivo pharmacokinetic study in rats, the relative oral bioavailability of decursinol (DOH), a hepatic metabolite of D and DA, in F8-administered mice was 8.75-fold higher than in AGN EtOH ext-treated group. In scopolamine-induced memory-impaired mice, F8 exhibited a more potent cognitive enhancing effect than AGN EtOH ext in both a Morris water maze test and a passive avoidance test. These findings suggest that HME-processed AGN/Soluplus formulation (F8) could be a promising therapeutic candidate for memory impairment.