An update on polymer-lipid hybrid systems for improving oral drug delivery

Introduction: A promising approach that has recently emerged to overcome the complex biobarriers and interrelated challenges associated with oral drug absorption is to combine the benefits of polymeric and lipid-based nanocarriers within one hybrid system. This multifaceted formulation strategy has given rise to a plethora of polymer-lipid hybrid (PLH) systems with varying nanostructures and biological activities, all of which have demonstrated the ability to improve the biopharmaceutical performance of a wide range of challenging therapeutics.

Areas covered: The multitude of polymers that can be combined with lipids to exert a synergistic effect for oral drug delivery have been identified, reviewed and critically evaluated. Specific focus is attributed to preclinical studies performed within the past 5 years that have elucidated the role and mechanism of the polymer phase in altering the oral absorption of encapsulated therapeutics.

Expert opinion: The potential of PLH systems has been clearly identified; however, improved understanding of the structure–activity relationship between PLH systems and oral absorption is fundamental for translating this promising delivery approach into a clinically relevant formulation. Advancing research within this field to identify optimal polymer, lipid combinations and engineering conditions for specific therapeutics are therefore encouraged.     

Design and evaluation of novel pH-sensitive chitosan nanoparticles for oral insulin delivery

Chitosan nanoparticles (CS NPs) have been commonly regarded as potential carriers for the mucosal delivery of therapeutic peptides because of their biocompatibility, bioadhesion and permeation enhancing properties. However, they have limited colloidal stability and readily dissociate and dissolve in the acidic gastric conditions. In the current study, CS NPs were formulated by ionic cross-linking with hydroxypropyl methylcellulose phthalate (HPMCP) as a pH-sensitive polymer and evaluated for the oral delivery of insulin. In vitro results revealed a superior acid stability of CS/HPMCP NPs with a significant control over insulin release and degradation in simulated acidic conditions with or without pepsin. Furthermore, fluorescently-labeled CS/HPMCP NPs showed a 2- to 4-fold improvement in the intestinal mucoadhesion and penetration compared to CS/TPP NPs as evidenced by quantitative fluorescence analysis and confocal microscopy. After s.c. injection to rats, no significant difference in the hypoglycemic effect of insulin solution or insulin-loaded CS/HPMCP NPs was observed, confirming the physico-chemical stability and biological activity of the entrapped peptide. Following peroral administration, CS/HPMCP NPs increased the hypoglycemic effect of insulin by more than 9.8 and 2.8-folds as compared to oral insulin solution and insulin-loaded CS/tripolyphosphate (TPP) NPs, respectively.     

Developed simvastatin chitosan nanoparticles co-crosslinked with tripolyphosphate and chondroitin sulfate for ASGPR-mediated targeted HCC delivery with enhanced oral bioavailability

Simvastatin (SV) repurposing has emerged as an alternative approach for the treatment of cancer. In this study, SV chitosan nanoparticles co-crosslinked with tripolyphosphate and chondroitin sulfate (SVCSChSNPs) were developed in order to maximize SV therapeutic efficiency. The hepatic targeting was realized using N-acetylgalactosamine (GalNAc) residues of ChS, which can be identified by the ASGPR receptors specifically expressed in hepatocytes. SV was repurposed as an anticancer agent against hepatocellular carcinoma (HCC). NPs were fabricated by the ionic gelation method, and the formulation variables (CS concentration, CS:ChS ratio, and CS solution pH) were optimized using a three-factor, three-level Box-Behnken design. The optimized NPs were investigated for particle size, size distribution, zeta potential, morphology, in vitro cytotoxicity, apoptotic effects against human hepatocellular carcinoma HepG2 cells, and detection of intracellular localization. The NPs were further evaluated for in vitro release behavior of SV and pharmacokinetics using Wister albino rats. Transmission electron microscopy (TEM) imaging showed a spherical shape with regular surface NPs of < 100 nm diameter. In vitro cytotoxicity testing showed that the SVCSChSNPs exhibited greater inhibition of proliferation in HepG2 cells and high cellular uptake through ASGPR-mediated endocytosis. The in vitro dissolution profile was 2.1-fold greater than that of pure SV suspension. Furthermore, in vivo oral pharmacokinetics revealed that the obtained NPs enhanced the bioavailability of SV by up to 2- and 1.6-fold for SV and SVA, respectively, compared to the pure SV suspension. These findings demonstrated that hepatic-targeted CSChSNPs delivering SV could potentially serve as a promising platform for HCC and other liver-related diseases.     

A novel polymer-lipid hybrid nanoparticle for efficient nonviral gene delivery

Aim:

To develop a novel non-viral vector with high transfection efficiency and low cytotoxicity.

Methods:

Poly (ethylene glycol)-distearoylphosphatidylethanolamine (PEG-DSPE) was incorporated into polymer-lipid hybrid nanoparticles (PLN) to construct a PEG-DSPE modified long circulating PLN (L-PLN). The L-PLN was prepared by the emulsifying-solvent evaporation method, L-PLN and L-PLN/DNA complexes were characterized. Both HEK293 and MDA-MB-231 cells transfected by L-PLN/DNA complexes were observed under a fluorescence microscope. The transfection efficiency of the complexes to HEK293 cells was further evaluated by flow cytometry.

Results:

The GFP fluorescence intensity in HEK293 cells transfected by the L-PLN/DNA complexes (N/P=10) was about 37.2%, which was higher than those transfected by PLN alone or commercial Lipofectamine^TM 2000. The L-PLN exhibited minimal toxicity at a low N/P ratio compared with other vectors.

Conclusion:

L-PLN as a novel gene delivery system, has higher transfection efficiency and acceptable cytotoxicity compared to the corresponding PLN, which is beneficial for the development of non-viral gene transfer vectors and may offer an alternative strategy for the future gene therapy.     

Bioadhesive polymer/lipid hybrid nanoparticles as oral delivery system of raloxifene with enhancive intestinal retention and bioavailability

Raloxifene (RLX) is a second-generation selective estrogen receptor modulator used to treat osteoporosis in postmenopausal women. RLX fails to be developed into injectable dosage forms due to poor solubility. Although oral formulations are clinically available, the lower bioavailability (<2%) embarrasses the pharmaceutists. This work reported a bioadhesive nanosystem intended for oral delivery of RLX to enhance its oral bioavailability and address the formulation challenge. The bioadhesive nanosystem refers to polymer–lipid hybrid nanoparticles made up of Carbopol 940, glyceryl distearate, and TGPS. RLX was solidly encapsulated into bioadhesive nanoparticles (bNPs) through a nanoprecipitation technique along with synchronous desalting of RLX·HCl. The resultant RLX-loaded bNPs (RLX-bNPs) were characterized by particle size, ζ potential, morphology, and entrapment efficiency. The in vitro release and in vivo oral bioavailability of RLX-bNPs in rats were comparatively investigated with RLX-loaded common lipid nanoparticles (RLX-cNPs). The preferred formulation possesses a particle size of 150 nm around with a polydispersity index (PDI) of 0.282. RLX-bNPs exhibited slower drug release than RLX-cNPs owing to the presence of an adhesive layer. After oral administration, RLX-bNPs resulted in significant enhancement in the bioavailability of RLX, up to 556.9% relative to RLX suspensions, while it was merely 244.7% for RLX-cNPs. Cellular testing and ex vivo transport imaging demonstrated that bNPs were endowed with excellent intestinal epithelial affinity and absorbability. Our study affords an alternative option for designing a suitable oral delivery system specific to amphiphobic drugs like RLX·HCl.     

Mucoadhesive hybrid gel improves intraperitoneal platinum delivery

A leading cause of death and suffering in patients with abdominal or pelvic malignancies is progression of peritoneal surface disease. Changes in the use of chemotherapy have shown significant survival benefits for intraperitoneal or combined intraperitoneal and intravenous treatment following optimal surgical cytoreduction. However, broader clinical use of intraperitoneal therapy has not reached its full potential due to limited efficacy, accessibility and nonspecific toxicity. To overcome these problems, we developed a mucoadhesive hybrid gel (HG) for a local, intraperitoneal drug delivery. In vivo studies confirmed reliable adherence and residence of the gel to the peritoneal sidewall for at least 72 h exhibiting no signs of tissue toxicity. Functionally active CDDP was released from HG within 2 h and was equal to free CDDP in vitro. Moreover, intraperitoneal application of HG-CDDP significantly enhanced CDDP accumulation in the genomic DNA of peritoneal tissues compared to the same CDDP dose administered intravenously. These findings indicate the potential application of this hybrid gel as a mucoadhesive drug carrier amendable to use for intraperitoneal drug delivery and possible expansion for use on other mucosal surfaces of the female reproductive tract.     

Hydrophobically modified carboxymethyl chitosan nanoparticles targeted delivery of paclitaxel

Specific targeting of tumor cells to achieve higher drug levels in tumor tissue and to overcome the side effects is the major goal in cancer therapy. Nanoparticles encapsulating a hydrophobic core in their nanoreservoir structure were developed as a carrier for a water-insoluble drug, paclitaxel. In the present study, target-oriented nanoparticles based on biodegradable O-carboxymethyl chitosan modified with stearic acid. The surface of the nanoparticles was modified by covalent attachment of folic acid (FA) by simple carbodimide reaction to achieve tumor cell targeting property. Nanoparticles were prepared by the sonication method without involving any surfactants/emulsifiers. The nanoparticles were characterized by various state-of-the-art techniques, including laser light scattering for particles size distribution, field emission scanning electron microscopy and transmission electron microscope for surface morphology. The drug release property and the cytotoxicity of the drug loaded nanoparticles to both cancerous and noncancerous cells were evaluated in cell culture system. To our knowledge, this is the first study demonstrating a FA modified hydrophobically chitosan with paclitaxel-loaded nanoparticles targeting of folate receptor overexpressing cancer cells.     

Influence of PEG coating on the oral bioavailability of gold nanoparticles in rats

Metallic nanoparticles can be produced in a variety of shapes, sizes, and surface chemistries, making them promising potential tools for drug delivery. Most studies to date have evaluated uptake of metallic nanoparticles from the GI tract with methods that are at best semi-quantitative. This study used the classical method of comparing blood concentration area under the curve (AUC) following intravenous and oral doses to determine the oral bioavailability of 1, 2 and 5?kDa PEG-coated 5?nm gold nanoparticles (AuNPs). Male rats were given a single intravenous dose (0.8?mg/kg) or oral (gavage) dose (8?mg/kg) of a PEG-coated AuNP, and the concentration of gold was measured in blood over time and in tissues (liver, spleen and kidney) at sacrifice. Blood concentrations following oral administration were inversely related to PEG size, and the AUC in blood was significantly greater for the 1?kDa PEG-coated AuNPs than particles coated with 2 or 5?kDa PEG. However, bioavailabilities of all of the particles were very low (相似文献   

Effects of verapamil on the pharmacokinetics of dihydromyricetin in rats and its potential mechanism

1. This study investigates the effects of verapamil on the pharmacokinetics of dihydromyricetin in rats and clarifies its main mechanism.

2. The pharmacokinetic profiles of oral or intravenous administration of dihydromyricetin in Sprague-Dawley rats with or without pretreatment with verapamil were investigated. In addition, the effects of verapamil on the transport and metabolic stability of dihydromyricetin were investigated using Caco-2 cell transwell model and rat liver microsomes.

3. In the oral group, verapamil could significantly increase C_max, and decrease oral clearance of dihydromyricetin (p?C_max also increased compared with the control group, but the difference was not significant. However, the t_1/2 and clearance rate decreased than that of the control (p?p?P-gp inhibitor, verapamil. Additionally, the intrinsic clearance rate of dihydromyricetin was decreased by the pretreatment with verapamil (27.0 versus 32.5?μL/min/mg protein).

4. Those results indicated that verapamil could significantly change the pharmacokinetic profiles of dihydromyricetin in rats, and it might exert these effects through increasing the absorption of dihydromyricetin by inhibiting the activity of P-gp, or through inhibiting the metabolism of dihydromyricetin in rat liver.     

Development and in vivo evaluation of chitosan nanoparticles for the oral delivery of albumin

Albumin is used as a plasma expander in critically ill patients and for several other clinical applications mainly via intravenous infusion. Oral administration of albumin can improve patient compliance although limited oral bioavailability of proteins is still a major challenge. Although nanomaterials have been extensively utilized for improving oral delivery of proteins, albumin has been utilized only as either a model drug or as a carrier for drug delivery. In the current study, for the first time, chitosan nanoparticles have been developed and extensively optimized to improve oral bioavailability of albumin as a therapeutic protein. Several characterizations have been performed for the albumin-loaded nanoparticles (e.g. drug encapsulation efficiency, DSC, FTIR, particle size, zeta potential, morphology, release kinetics, and enzymatic stability). Nanosized spherical particles were prepared and demonstrated high stability over three months either in a powdered form or as suspensions. Sustained release of albumin over time and high enzymatic stability as compared to the free albumin were observed. In vivo, higher serum concentrations of albumin in normal rabbits and cirrhotic rats were attained following oral and intraperitoneal administrations of the albumin-loaded nanoparticles as compared to the free albumin. The nanoparticles developed in the current study might provide efficient nanovehicles for oral administration of therapeutic albumin.     

The upregulated intestinal folate transporters direct the uptake of ligand-modified nanoparticles for enhanced oral insulin delivery

Transporters are traditionally considered to transport small molecules rather than large-sized nanoparticles due to their small pores. In this study, we demonstrate that the upregulated intestinal transporter (PCFT), which reaches a maximum of 12.3-fold expression in the intestinal epithelial cells of diabetic rats, mediates the uptake of the folic acid-grafted nanoparticles (FNP). Specifically, the upregulated PCFT could exert its function to mediate the endocytosis of FNP and efficiently stimulate the traverse of FNP across enterocytes by the lysosome-evading pathway, Golgi-targeting pathway and basolateral exocytosis, featuring a high oral insulin bioavailability of 14.4% in the diabetic rats. Conversely, in cells with relatively low PCFT expression, the positive surface charge contributes to the cellular uptake of FNP, and FNP are mainly degraded in the lysosomes. Overall, we emphasize that the upregulated intestinal transporters could direct the uptake of ligand-modified nanoparticles by mediating the endocytosis and intracellular trafficking of ligand-modified nanoparticles via the transporter-mediated pathway. This study may also theoretically provide insightful guidelines for the rational design of transporter-targeted nanoparticles to achieve efficient drug delivery in diverse diseases.     

pH-sensitive nanoparticles for improving the oral bioavailability of cyclosporine A

The purpose of this work was to improve the oral bioavailability of cyclosporine A (CyA) by preparation the CyA-pH sensitive nanoparticles. The CyA-pH sensitive nanoparticles were prepared by using poly(methacrylic acid and methacrylate) copolymer. The characterization and the dispersion state of CyA at the surface or inside the polymeric matrices of the nanoparticles were investigated. The in vitro release studies were conducted by ultracentrifuge method. The bioavailability of CyA from nanoparticles and Neoral microemulsion was assessed in Sprague–Dawley (SD) rats at a dose of 15 mg/kg. The particle size of the nanoparticles was within the range from 37.4 ± 5.6 to 106.7 ± 14.8 nm. The drug entrapped efficiency was very high (from 90.9 to 99.9%) and in all cases the drug was amorphous or molecularly dispersed within the nanoparticles polymeric matrices. In vitro release experiments revealed that the nanoparticles exhibited perfect pH-dependant release profiles. The relative bioavailability of CyA was markedly increased by 32.5% for CyA-S100 nanoparticles (P < 0.05), and by 15.2% and 13.6% for CyA-L100-55 and CyA-L100 nanoparticles respectively, while it was decreased by 5.2% from CyA-E100 nanoparticles when compared with the Neoral microemulsion. With these results, the potential of pH-sensitive nanoparticles for the oral delivery of CyA was confirmed.     

Lipid nanoparticles for parenteral delivery of actives

The present review compiles the applications of lipid nanoparticles mainly solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC) and lipid drug conjugates (LDC) in parenteral delivery of pharmaceutical actives. The attempts to incorporate anticancer agents, imaging agents, antiparasitics, antiarthritics, genes for transfection, agents for liver, cardiovascular and central nervous system targeting have been summarized. The utility of lipid nanoparticles as adjuvant has been discussed separately. A special focus of this review is on toxicity caused by these kinds of lipid nanoparticles with a glance on the fate of lipid nanoparticles after their parenteral delivery in vivo viz the protein adsorption patterns.     

The in vivo fate of nanoparticles and nanoparticle-loaded microcapsules after oral administration in mice: Evaluation of their potential for colon-specific delivery

Anti-cancer drug loaded-nanoparticles (NPs) or encapsulation of NPs in colon-targeted delivery systems shows potential for increasing the local drug concentration in the colon leading to improved treatment of colorectal cancer. To investigate the potential of the NP-based strategies for colon-specific delivery, two formulations, free Eudragit® NPs and enteric-coated NP-loaded chitosan–hypromellose microcapsules (MCs) were fluorescently-labelled and their tissue distribution in mice after oral administration was monitored by multispectral small animal imaging. The free NPs showed a shorter transit time throughout the mouse digestive tract than the MCs, with extensive excretion of NPs in faeces at 5 h. Conversely, the MCs showed complete NP release in the lower region of the mouse small intestine at 8 h post-administration. Overall, the encapsulation of NPs in MCs resulted in a higher colonic NP intensity from 8 h to 24 h post-administration compared to the free NPs, due to a NP ‘guarding’ effect of MCs during their transit along mouse gastrointestinal tract which decreased NP excretion in faeces. These imaging data revealed that this widely-utilised colon-targeting MC formulation lacked site-precision for releasing its NP load in the colon, but the increased residence time of the NPs in the lower gastrointestinal tract suggests that it is still useful for localised release of chemotherapeutics, compared to NP administration alone. In addition, both formulations resided in the stomach of mice at considerable concentrations over 24 h. Thus, adhesion of NP- or MC-based oral delivery systems to gastric mucosa may be problematic for colon-specific delivery of the cargo to the colon and should be carefully investigated for a full evaluation of particulate delivery systems.     

Preparation,characterization, and in vivo study of rhein solid lipid nanoparticles for oral delivery

In this study, rhein‐SLN s were successfully produced by hot homogenization followed by ultrasonication. Precirol ATO 5 in which rhein exhibited higher partition coefficient was selected for preparation of SLN s. In the dynamic light scattering, the rhein‐SLN s showed a smaller size with a mean value of 120.8 ± 7.9 nm and with zeta potential of ?16.9 ± 2.3 mV. SLN s exhibited a good stability during the period of 2 months. The SLN s indicated faster drug release with a burst release within 2 hr and followed by a sustained release with a biphasic drug‐release pattern. Comparing with the same concentration (free drug), the cellular cytotoxicity of rhein‐loaded SLN s increased significantly at the same incubation condition. In vivo, the AUC _0‐t of rhein in the form of SLN s was significantly increased and was 2.06‐fold that of suspensions group. The results showed an increased oral absorption and improved the oral bioavailability of rhein by the formulation of SLN s.     

Progress in oral insulin delivery by PLGA nanoparticles for the management of diabetes

Currently, the only practical way to treat type 1 and advanced insulin-dependent type 2 diabetes mellitus (T1/2DM) is the frequent subcutaneous injection of insulin, which is significantly different physiologically from endogenous insulin secretion from pancreatic islets and can lead to hyperinsulinemia, pain, and infection in patients with poor compliance. Hence, oral insulin delivery has been actively pursued to revolutionize the treatment of insulin-dependent diabetes. In this review, we provide an overview of recent progress in developing poly(lactic co-glycolic acid) (PLGA) nanoparticles (NPs) for oral insulin delivery. Different strategies for insulin-loaded PLGA NPs to achieve normoglycemic effects are discussed. Finally, challenges and future perspectives of PLGA NPs for oral insulin delivery are put forward.     

PLGA nanoparticles for the oral delivery of nuciferine: preparation,physicochemical characterization and in vitro/in vivo studies

This article reports a promising approach to enhance the oral delivery of nuciferine (NUC), improve its aqueous solubility and bioavailability, and allow its controlled release as well as inhibiting lipid accumulation. NUC-loaded poly lactic-co-glycolic acid nanoparticles (NUC-PLGA-NPs) were prepared according to a solid/oil/water (s/o/w) emulsion technique due to the water-insolubility of NUC. PLGA exhibited excellent loading capacity for NUC with adjustable dosing ratios. The drug loading and encapsulation efficiency of optimized formulation were 8.89?±?0.71 and 88.54?±?7.08%, respectively. NUC-PLGA-NPs exhibited a spherical morphology with average size of 150.83?±?5.72?nm and negative charge of ?22.73?±?1.63?mV, which are suitable for oral administration. A sustained NUC released from NUC-PLGA-NPs with an initial exponential release owing to the surface associated drug followed by a slower release of NUC, which was entrapped in the core. In addition, ～77?±?6.67% was released in simulating intestinal juice, while only about 45.95?±?5.2% in simulating gastric juice. NUC-PLGA-NPs are more efficient against oleic acid (OA)-induced hepatic steatosis in HepG₂ cells when compared to naked NUC (n-NUC, *p < 0.05). The oral bioavailability of NUC-PLGA-NPs group was significantly higher (**p < 0.01) and a significantly decreased serum levels of total cholesterol (TC), triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C), as well as a higher concentration of high-density lipoprotein cholesterol (HDL-C) was observed, compared with that of n-NUC treated group. These findings suggest that NUC-PLGA-NPs hold great promise for sustained and controlled drug delivery with improved bioavailability to alleviating lipogenesis.     

Versatile flexible micelles integrating mucosal penetration and intestinal targeting for effectively oral delivery of paclitaxel

The extremely low bioavailability of oral paclitaxel(PTX) mainly due to the complicated gastrointestinal environment,the obstruction of intestinal mucus layer and epithelium barrier.Thus,it is of great significance to construct a coordinative delivery system which can overcome multiple intestinal physicochemical obstacles simultaneously.In this work,a high-density PEGylation-based glycocholic acid-decorated micelles(PTX@GNPs) was constructed by a novel polymer,9-Fluorenylmethoxy carbonyl-poly et...     

Chitosan phthalate microspheres for oral delivery of insulin: preparation, characterization, and in vitro evaluation

Chitosan phthalate polymer was synthesized and its microspheres were prepared by emulsion phase separation technique. The characterization of microspheres was determined by means of FTIR spectroscopy, electron microscopy, particle size, and zeta potential. The insulin was loaded to the microspheres by passive absorption technique. The peptic and tryptic enzymes degradation of insulin in microspheres was investigated. The in vitro release behavior of the microspheres was investigated under different pH conditions (pH 2.0 and pH 7.4). The degree of phthalate substitution in the synthesized polymer was 20%. The prepared microspheres were spherical with an average diameter 46.34 μ m. The insulin-loading capacity was 62%. Chitosan phthalate microspheres protect the insulin from gastric enzymes degradation that may enhance the oral stability of insulin. The encapsulated insulin was quickly released in a phosphate buffer saline (pH 7.4), whereas a small amount of insulin was released under acidic condition (0.1N HCl; pH 2.0) because under acidic conditions, carboxylic groups present in the system exist in nonionized form and are poorly hydrophilic. However, in alkaline conditions, it exists in ionized form and is considerably hydrophilic. The results suggest that chitosan phthalate microspheres may be used as a potential carrier for oral insulin delivery.