Cell-penetrating self-nanoemulsifying drug delivery systems (SNEDDS) for oral gene delivery

Triamcinolone-loaded self nano-emulsifying drug delivery systems for ocular use: An alternative to invasive ocular surgeries and injections

Inflammation of the posterior segment of the eye is a severe condition and hard to cure as delivery of drugs to the inflammation site is inefficient. Currently, the primary treatment approach is ocular surgery or invasive ocular injections. Herein, we designed and developed a topically self nano-emulsifying drug delivery system (SNEDDs) to deliver triamcinolone acetonide (TCA) to the posterior segment of the eye. A screening based on TCA solubility was conducted on each excipient followed by preparation of various formulations using different ratios of the selected excipients. Vesicles of optimized SNEDDs had less than 100 nm size and spherical morphology. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay showed self-emulsified vesicles have relatively high safety on retinal pigment epithelium (RPE) cell line. Furthermore, efficient cellular uptake of coumarin 6-loaded SNEDDs in RPE using confocal laser scanning microscopy (CLSM) was confirmed. In addition, an in-vivo study using hematoxylin and eosin (H&E) staining revealed that 14 days of topical treatment of albino rabbit eyes with TCA-loaded SNEDDs was safe and no sign of tissue destruction and inflammation was detected in different parts of the eye sections including cornea, sclera, retina, and optic nerve. Also, the CLSM images from topically treated eyes with coumarin 6 (a hydrophobic, fluorescent drug model) loaded SNEDDs, showed that the optimized SNEDDs could properly penetrate toward the posterior segments of the eye especially the retina, posterior parts of the choroid, and sclera. Considering the outstanding results obtained by ocular tissue penetration and low toxicity, prepared SNEDDs, have the potential to be used as a topical administration for treating posterior segment disorders of the eye through an utterly non-invasive route and TCA-loaded SNEDDs could be an alternative for TCA intravitreal and intra conjunctival injections.

Recent Progress in the Oral Delivery of Therapeutic Peptides and Proteins: Overview of Pharmaceutical Strategies to Overcome Absorption Hurdles

Purpose

Proteins and peptides have secured a place as excellent therapeutic moieties on account of their high selectivity and efficacy. However due to oral absorption limitations, current formulations are mostly delivered parenterally. Oral delivery of peptides and proteins (PPs) can be considered the need of the hour due to the immense benefits of this route. This review aims to critically examine and summarize the innovations and mechanisms involved in oral delivery of peptide and protein drugs.

Methods

Comprehensive literature search was undertaken, spanning the early development to the current state of the art, using online search tools (PubMed, Google Scholar, ScienceDirect and Scopus).

Results

Research in oral delivery of proteins and peptides has a rich history and the development of biologics has encouraged additional research effort in recent decades. Enzyme hydrolysis and inadequate permeation into intestinal mucosa are the major causes that result in limited oral absorption of biologics. Pharmaceutical and technological strategies including use of absorption enhancers, enzyme inhibition, chemical modification (PEGylation, pro-drug approach, peptidomimetics, glycosylation), particulate delivery (polymeric nanoparticles, liposomes, micelles, microspheres), site-specific delivery in the gastrointestinal tract (GIT), membrane transporters, novel approaches (self-nanoemulsifying drug delivery systems, Eligen technology, Peptelligence, self-assembling bubble carrier approach, luminal unfolding microneedle injector, microneedles) and lymphatic targeting, are discussed. Limitations of these strategies and possible innovations for improving oral bioavailability of protein and peptide drugs are discussed.

Conclusion

This review underlines the application of oral route for peptide and protein delivery, which can direct the formulation scientist for better exploitation of this route.

Non-antibiotic strategies for prevention and treatment of internalized Staphylococcus aureus

Staphylococcus aureus (S. aureus) infections are often difficult to cure completely. One of the main reasons for this difficulty is that S. aureus can be internalized into cells after infecting tissue. Because conventional antibiotics and immune cells have difficulty entering cells, the bacteria can survive long enough to cause recurrent infections, which poses a serious burden in healthcare settings because repeated infections drastically increase treatment costs. Therefore, preventing and treating S. aureus internalization is becoming a research hotspot. S. aureus internalization can essentially be divided into three phases: (1) S. aureus binds to the extracellular matrix (ECM), (2) fibronectin (Fn) receptors mediate S. aureus internalization into cells, and (3) intracellular S. aureus and persistence into cells. Different phases require different treatments. Many studies have reported on different treatments at different phases of bacterial infection. In the first and second phases, the latest research results show that the cell wall-anchored protein vaccine and some microbial agents can inhibit the adhesion of S. aureus to host cells. In the third phase, nanoparticles, photochemical internalization (PCI), cell-penetrating peptides (CPPs), antimicrobial peptides (AMPs), and bacteriophage therapy can effectively eliminate bacteria from cells. In this paper, the recent progress in the infection process and the prevention and treatment of S. aureus internalization is summarized by reviewing a large number of studies.

Oral delivery of therapeutic peptides and proteins: Technology landscape of lipid-based nanocarriers

The oral administration of therapeutic peptides and proteins is favoured from a patient and commercial point of view. In order to reach the systemic circulation after oral administration, these drugs have to overcome numerous barriers including the enzymatic, sulfhydryl, mucus and epithelial barrier. The development of oral formulations for therapeutic peptides and proteins is therefore necessary. Among the most promising formulation approaches are lipid-based nanocarriers such as oil-in-water nanoemulsions, self-emulsifying drug delivery systems (SEDDS), solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), liposomes and micelles. As the lipophilic character of therapeutic peptides and proteins can be tremendously increased such as by the formation of hydrophobic ion pairs (HIP) with hydrophobic counter ions, they can be incorporated in the lipophilic phase of these carriers. Since gastrointestinal (GI) peptidases as well as sulfhydryl compounds such as glutathione and dietary proteins are too hydrophilic to enter the lipophilic phase of these carriers, the incorporated therapeutic peptide or protein is protected towards enzymatic degradation as well as unintended thiol/disulfide exchange reactions. Stability of lipid-based nanocarriers towards lipases can be provided by the use to excipients that are not or just poorly degraded by these enzymes. Nanocarriers with a size <200 nm and a mucoinert surface such as PEG or zwitterionic surfaces exhibit high mucus permeating properties. Having reached the underlying absorption membrane, lipid-based nanocarriers enable paracellular and lymphatic drug uptake, induce endocytosis and transcytosis or simply fuse with the cell membrane releasing their payload into the systemic circulation. Numerous in vivo studies provide evidence for the potential of these delivery systems. Within this review we provide an overview about the different barriers for oral peptide and protein delivery, highlight the progress made on lipid-based nanocarriers in order to overcome them and discuss strengths and weaknesses of these delivery systems in comparison to other technologies.

Self-nanoemulsifying composition containing curcumin, quercetin, Ganoderma lucidum extract powder and probiotics for effective treatment of type 2 diabetes mellitus in streptozotocin induced rats

Liquid self-nanoemulsifying drug delivery system (L-SNEDDS) of curcumin and quercetin were prepared by dissolving them in isotropic mixture of Labrafil M1944CS®, Capmul MCM®, Tween-80® and Transcutol P®. The prepared L-SNEDDS were solidified using Ganoderma lucidum extract, probiotics and Aerosil-200® using spray drying. These were further converted into pellets using extrusion-spheronization. The mean droplet size and zeta potential of L-SNEDDS were found to be 63.46 ± 2.12 nm and - 14.8 ± 3.11 mV while for solid SNEDDS pellets, these were 72.46 ± 2.16 nm and -38.7 ± 1.34 mV, respectively. The dissolution rate for curcumin and quercetin each was enhanced by 4.5 folds while permeability was enhanced by 5.28 folds (curcumin) and 3.35 folds (quercetin) when loaded into SNEDDS pellets. The Cmax for curcumin and quercetin containing SNEDDS pellets was found 532.34 ± 5.64 ng/mL and 4280 ± 65.67 ng/mL, respectively. This was 17.55 and 3.48 folds higher as compared to their naïve forms. About 50.23- and 5.57-folds increase in bioavailability was observed for curcumin and quercetin respectively, upon loading into SNEDDS pellets. SNEDDS pellets were found stable at accelerated storage conditions. The developed formulation was able to normalize the levels of blood glucose, lipids, antioxidant biomarkers, and tissue architecture of pancreas and liver in streptozotocin induced diabetic rats as compared to their naïve forms.

Natural Nano-Drug Delivery System in Coptidis Rhizoma Extract with Modified Berberine Hydrochloride Pharmacokinetics

Purpose

This study aimed to evaluate the pharmaceutical and pharmacokinetic effects of the natural nanoparticles (Nnps) isolated from Coptidis Rhizoma extract on berberine hydrochloride (BBR) and systematically explore the related mechanisms.

Methods

Firstly, Nnps were isolated from Coptidis Rhizoma extract and then an Nnps-BBR complex was prepared. After qualitative and quantitative analysis in terms of size, Zeta potential, morphology, and composition of the Nnps and the Nnps-BBR complex, the effects of the Nnps on the crystallization of BBR were characterized. The effects of the Nnps on the solubility and dissolution of BBR were then evaluated. In addition, the effects of the Nnps on BBR in terms of cellular uptake, transmembrane transport, metabolic stability, and pharmacokinetics in mice were studied.

Results

The Nnps had an average size of 166.6 ± 1.3 nm and Zeta potential of −12.5 ± 0.2 mV. The Nnps were formed by denaturation of co-existing plant proteins with molecular weight < 30 kDa. The Nnps adsorbed or dispersed BBR, thereby promoting BBR transformation from crystal to amorphous form and improving its solubility and dissolution. The Nnps carried and promoted BBR uptake by human colonic adenocarcinoma (Caco-2) cells via caveolae-mediated endocytosis, reducing P-gp-mediated efflux of BBR in mice gut sacs and Madin-Darby canine kidney cells stably expressing the transporter P-gp (MDCK-MDR1) cells. Moreover, the Nnps improved BBR metabolic stability in mouse intestinal S9, promoting BBR intestinal absorption in mice, as shown by increased peak BBR concentration (C_max, 1182.3 vs 310.2 ng/mL) and exposure level (AUC_{0–12 h}, 2842.8 vs 1447.0 ng·h/mL) in mouse portal vein. In addition, the Nnps increased BBR exposure level in mouse livers (95,443.2 vs 43,586.2 ng·h/g liver).

Conclusion

The proteinaceous nanoparticles isolated from Coptidis Rhizoma extract can form a natural nano-drug delivery system with BBR, thereby significantly improving the pharmacokinetics of oral BBR.

Fabrication of pH/Reduction Sensitive Polyethylene Glycol-Based Micelles for Enhanced Intracellular Drug Release

At present, the drug is still difficult to release completely and quickly only with single stimulation. In order to promote the rapid release of polymeric micelles at tumor site, pH/reduction sensitive polymers (PCT) containing disulfide bonds and orthoester groups were synthesized. The PCT polymers can self-assemble in water and entrap doxorubicin to form drug-loaded micelles (DOX/PCT). In an in vitro drug release experiment, the cumulative release of DOX/PCT micelles in the simulated tumor microenvironment (pH 5.0 with GSH) reached (89.7 ± 11.7)% at 72 h, while it was only (16.7 ± 6.1)% in the normal physiological environment (pH 7.4 without GSH). In addition, pH sensitive DOX loaded micellar system (DOX/PAT) was prepared as a control. Furthermore, compared with DOX/PAT micelles, DOX/PCT micelles showed the stronger cytotoxicity against tumor cells to achieve an effective antitumor effect. After being internalized by clathrin/caveolin-mediated endocytosis and macropinocytosis, DOX/PCT micelles were depolymerized in intercellular acidic and a reductive environment to release DOX rapidly to kill tumor cells. Additionally, DOX/PCT micelles had a better inhibitory effect on tumor growth than DOX/PAT micelles in in vivo antitumor activity studies. Therefore, pH/reduction dual sensitive PCT polymers have great potential to be used as repaid release nanocarriers for intercellular delivery of antitumor drugs.

Cell-penetrating peptides (CPPs): an overview of applications for improving the potential of nanotherapeutics

In the field of nanotherapeutics, gaining cellular entry into the cytoplasm of the target cell continues to be an ultimate challenge. There are many physicochemical factors such as charge, size and molecular weight of the molecules and delivery vehicles, which restrict their cellular entry. Hence, to dodge such situations, a class of short peptides called cell-penetrating peptides (CPPs) was brought into use. CPPs can effectively interact with the cell membrane and can assist in achieving the desired intracellular entry. Such strategy is majorly employed in the field of cancer therapy and diagnosis, but now it is also used for other purposes such as evaluation of atherosclerotic plaques, determination of thrombin levels and HIV therapy. Thus, the current review expounds on each of these mentioned aspects. Further, the review briefly summarizes the basic know-how of CPPs, their utility as therapeutic molecules, their use in cancer therapy, tumor imaging and their assistance to nanocarriers in improving their membrane penetrability. The review also discusses the challenges faced with CPPs pertaining to their stability and also mentions the strategies to overcome them. Thus, in a nutshell, this review will assist in understanding how CPPs can present novel possibilities for resolving the conventional issues faced with the present-day nanotherapeutics.

Gastrointestinal lipolysis and trans-epithelial transport of SMEDDS via oral route

Self-microemulsifying drug delivery systems (SMEDDSs) have recently returned to the limelight of academia and industry due to their enormous potential in oral delivery of biomacromolecules. However, information on gastrointestinal lipolysis and trans-epithelial transport of SMEDDS is rare. Aggregation-caused quenching (ACQ) fluorescent probes are utilized to visualize the in vivo behaviors of SMEDDSs, because the released probes during lipolysis are quenched upon contacting water. Two SMEDDSs composed of medium chain triglyceride and different ratios of Tween-80 and PEG-400 are set as models, meanwhile Neoral® was used as a control. The SMEDDS droplets reside in the digestive tract for as long as 24 h and obey first order kinetic law of lipolysis. The increased chain length of the triglyceride decreases the lipolysis of the SMEDDSs. Ex vivo imaging of main tissues and histological examination confirm the trans-epithelial transportation of the SMEDDS droplets. Approximately 2%-4% of the given SMEDDSs are transported via the lymph route following epithelial uptake, while liver is the main termination. Caco-2 cell lines confirm the cellular uptake and trans-epithelial transport. In conclusion, a fraction of SMEDDSs can survive the lipolysis in the gastrointestinal tract, permeate across the epithelia, translocate via the lymph, and accumulate mainly in the liver.

Oligonucleotide Delivery across the Caco-2 Monolayer: The Design and Evaluation of Self-Emulsifying Drug Delivery Systems (SEDDS)

Oligonucleotides (OND) represent a promising therapeutic approach. However, their instability and low intestinal permeability hamper oral bioavailability. Well-established for oral delivery, self-emulsifying drug delivery systems (SEDDS) can overcome the weakness of other delivery systems such as long-term instability of nanoparticles or complicated formulation processes. Therefore, the present study aims to prepare SEDDS for delivery of a nonspecific fluorescently labeled OND across the intestinal Caco-2 monolayer. The hydrophobic ion pairing of an OND and a cationic lipid served as an effective hydrophobization method using either dimethyldioctadecylammonium bromide (DDAB) or 1,2-dioleoyl-3-trimethylammonium propane (DOTAP). This strategy allowed a successful loading of OND-cationic lipid complexes into both negatively charged and neutral SEDDS. Subjecting both complex-loaded SEDDS to a nuclease, the negatively charged SEDDS protected about 16% of the complexed OND in contrast to 58% protected by its neutral counterpart. Furthermore, both SEDDS containing permeation-enhancing excipients facilitated delivery of OND across the intestinal Caco-2 cell monolayer. The negatively charged SEDDS showed a more stable permeability profile over 120 min, with a permeability of about 2 × 10^-7 cm/s, unlike neutral SEDDS, which displayed an increasing permeability reaching up to 7 × 10^-7 cm/s. In conclusion, these novel SEDDS-based formulations provide a promising tool for OND protection and delivery across the Caco-2 cell monolayer.

Polyphosphate coatings: A promising strategy to overcome the polycation dilemma

AIM

It was the aim of this study to develop a zeta potential changing drug delivery system by decorating lipid-based nanocarriers with a polycationic cell penetrating peptide (CPP) and subsequently masking these cationic substructures with polyphosphates.

METHODS

In order to anchor the CPP poly-l-lysine (PLL) on the surface of the oily droplets of an o/w nanoemulsion, stearic acid was covalently attached to the peptide. The resulting CPP-decorated oily droplets were coated with phytic acid and tripolyphosphate. The elimination of these polyphosphates due to cleavage by alkaline phosphatase was monitored by the release of monophosphate from the surface of the nanocarriers, by the change in zeta potential and by cellular uptake studies on Caco-2 cells.

RESULTS

Polyphosphate coated PLL-decorated nanocarriers exhibited a pronounced conversion of zeta potential from -14.1 mV to +4.2 mV in case of tripolyphosphate coated nanocarriers and from -9.9 mV to -2.6 mV in case of phytic acid coated nanocarriers. The cellular uptake on Caco-2 cells of the polyphosphate coated nanocarriers was 4-fold improved compared to the control nanocarriers. Furthermore, confocal images showed that the majority of nanodroplets distributed in cytoplasm not being internalized into lysosomes.

CONCLUSION

Polyphosphate coating of CPP-decorated nanocarriers seems to be a promising and simple strategy to overcome the polycation dilemma.

Self-Nano-Emulsifying Drug-Delivery Systems: From the Development to the Current Applications and Challenges in Oral Drug Delivery

Approximately one third of newly discovered drug molecules show insufficient water solubility and therefore low oral bio-availability. Self-nano-emulsifying drug-delivery systems (SNEDDSs) are one of the emerging strategies developed to tackle the issues associated with their oral delivery. SNEDDSs are composed of an oil phase, surfactant, and cosurfactant or cosolvent. SNEDDSs characteristics, their ability to dissolve a drug, and in vivo considerations are determinant factors in the choice of SNEDDSs excipients. A SNEDDS formulation can be optimized through phase diagram approach or statistical design of experiments. The characterization of SNEDDSs includes multiple orthogonal methods required to fully control SNEDDS manufacture, stability, and biological fate. Encapsulating a drug in SNEDDSs can lead to increased solubilization, stability in the gastro-intestinal tract, and absorption, resulting in enhanced bio-availability. The transformation of liquid SNEDDSs into solid dosage forms has been shown to increase the stability and patient compliance. Supersaturated, mucus-permeating, and targeted SNEDDSs can be developed to increase efficacy and patient compliance. Self-emulsification approach has been successful in oral drug delivery. The present review gives an insight of SNEDDSs for the oral administration of both lipophilic and hydrophilic compounds from the experimental bench to marketed products.

Development and In Vitro Evaluation of Stearic Acid Phosphotyrosine Amide as New Excipient for Zeta Potential Changing Self-Emulsifying Drug Delivery Systems

PURPOSE

Development of zeta potential changing SEDDS containing newly synthesized derivative stearic acid phosphotyrosine amide.

METHODS

Stearoyl chloride was conjugated with phosphotyrosine, which is substrate for the brush border enzyme intestinal alkaline phosphate. The synthesized derivative was implemented in different SEDDS formulations and the zeta potential changing properties and the concluding mucus diffusion abilities were evaluated.

RESULTS

Stearic acid phosphotyrosine amide was successfully synthesized and incorporated into SEDDS. A SEDDS formulation containing the new derivative showed a zeta potential of -14 mV before, and + 2 mV after enzymatic cleavage by intestinal alkaline phosphatase. Experiments on a Caco-2 monolayer demonstrated that the phosphate cannot only be cleaved by isolated enzyme, but also by enzyme, which was expressed by cells. The mucus diffusion abilities of the untreated, negatively charged SEDDS were significantly higher compared to the enzymatically cleaved, positively charged SEDDS.

CONCLUSION

The developed stearic acid phosphotyrosine represents a promising excipient for zeta potential changing SEDDS. Graphical Abstract.

Sphingomyelin-Based Nanosystems (SNs) for the Development of Anticancer miRNA Therapeutics

Gene replacement therapy with oncosuppressor microRNAs (miRNAs) is a promising alternative to interfere with cancer progression. However, miRNAs are highly inefficient in a biological environment, hampering a successful translation to clinics. Nanotechnology can tackle this drawback by providing delivery systems able to efficiently deliver them to cancer cells. Thus, the objective of this work was to develop biocompatible nanosystems based on sphingomyelin (SM) for the intracellular delivery of miRNAs to colorectal cancer cells. We pursued two different approaches to select the most appropriate composition for miRNA delivery. On the one hand, we prepared sphingomyelin-based nanosystems (SNs) that incorporate the cationic lipid stearylamine (ST) to support the association of miRNA by the establishment of electrostatic interactions (SNs–ST). On the other hand, the cationic surfactant (DOTAP) was used to preform lipidic complexes with miRNA (Lpx), which were further encapsulated into SNs (SNs-Lpx). Restitution of miRNA145 levels after transfection with SNs-Lpx was related to the strongest anticancer effect in terms of tumor proliferation, colony forming, and migration capacity assays. Altogether, our results suggest that SNs have the potential for miRNA delivery to develop innovative anticancer therapies.

Improved Nucleic Acid Therapy with Advanced Nanoscale Biotechnology

Due to a series of systemic and intracellular obstacles in nucleic acid (NA) therapy, including fast degradation in blood, renal clearance, poor cellular uptake, and inefficient endosomal escape, NAs may need delivery methods to transport to the cell nucleus or cytosol to be effective. Advanced nanoscale biotechnology-associated strategies, such as controlling the particle size, charge, drug loading, response to environmental signals, or other physical/chemical properties of delivery carriers, have provided great help for the in vivo and in vitro delivery of NA therapeutics. In this review, we introduce the characteristics of different NA modalities and illustrate how advanced nanoscale biotechnology assists NA therapy. The specific features and challenges of various nanocarriers in clinical and preclinical studies are summarized and discussed. With the help of advanced nanoscale biotechnology, some of the major barriers to the development of NA therapy will eventually be overcome in the near future.

Zeta potential changing self-emulsifying drug delivery systems: A promising strategy to sequentially overcome mucus and epithelial barrier

AIM

The aim of the present study was to develop zeta potential changing self-emulsifying drug delivery systems (SEDDS) via a flip-flop mechanism in order to improve their mucus permeating and cellular uptake properties.

METHODS

Phosphorylated serine-oleylamine (p-Ser-OA) conjugates were synthesized and incorporated into SEDDS at a concentration of 1% (v/v). Cytotoxic potential of p-Ser-OA and p-Ser-OA loaded SEDDS was investigated on Caco-2 cells. Phosphate release was evaluated using isolated as well as cell-associated intestinal alkaline phosphatase (AP). In parallel, change in zeta potential and amino group concentration on the surface of SEDDS was determined. Furthermore, mucus permeation and cellular uptake studies were performed.

RESULTS

p-Ser-OA was synthesized by covalent attachment of serine (Ser) to oleylamine (OA) via a carbodiimide-mediated reaction followed by phosphorylation using phosphorous pentoxide (P₂O₅) and phosphoric acid (H₃PO₄). The chemical structure of p-Ser-OA was confirmed via FT-IR, ¹H NMR, ¹³C NMR, ³¹P NMR and mass spectroscopic analysis. p-Ser-OA loaded SEDDS exhibited a droplet size and zeta potential of 46.42 ± 0.35 nm and -11.53 mV, respectively. A significant amount of phosphate was released after incubation with isolated as well as cell-associated AP within 6 h and zeta potential raised up to -2.04 mV. p-Ser-OA loaded SEDDS showed improved mucus permeation in comparison to p-Ser-OA loaded SEDDS treated with AP. Moreover, cellular uptake increased almost 2-fold after phosphate cleavage using AP.

CONCLUSION

Findings of this study show that SEDDS changing their zeta potential via a flip-flop mechanism exhibit both high mucus permeating and high cellular uptake properties.

Oral delivery of non-viral nucleic acid-based therapeutics - do we have the guts for this?

Gene therapy with RNA and pDNA-based drugs is limited by poor enzymatic stability and poor cellular permeation. The delivery of nucleic acids, in particular by the oral route, remains a major hurdle. This review will focus on the barriers to the oral delivery of nucleic acids and the strategies, in particular formulation strategies, which have been developed to overcome these barriers. Due to their very low oral bioavailability, the most obvious and most investigated biomedical applications for their oral delivery are related to the local treatment of inflammatory bowel diseases and colorectal cancers. Preclinical data but not yet clinical studies support the potential use of the oral route for the local delivery of formulated nucleic acid-based drugs.

SEDDS: A game changing approach for the oral administration of hydrophilic macromolecular drugs

Since the development of self-emulsifying drug delivery systems (SEDDS) in 1980's, they attract the attention of researchers in order to confront the challenge of poor water-solubility of orally given drugs. Within recent years, SEDDS were also discovered for oral administration of hydrophilic macromolecular drugs such as peptides, proteins, polysaccharides and pDNA. Due to hydrophobic ion pairing (HIP) with oppositely charged lipophilic auxiliary agents the resulting complexes can be incorporated in the lipophilic phase of SEDDS. Depending on the solubility of the complex in the SEDDS pre-concentrate and in the release medium drug release can be adjusted on purpose by choosing more or less lipophilic auxiliary agents in appropriate quantities for HIP. Within the oily droplets formed in the GI-tract drugs are protected towards degradation by proteases and nucleases and thiol-disulfide exchange reactions with dietary proteins. The oily droplets can be made mucoadhesive or highly mucus permeating depending on their target site. Furthermore, even their cellular uptake properties can be tuned by adjusting their zeta potential or decorating them with cell penetrating peptides. The potential of SEDDS for oral administration of hydrophilic macromolecular drugs could meanwhile be demonstrated via various in vivo studies showing a bioavailability at least in the single digit percentage range. Owing to these properties advanced SEDDS turned out to be a game changing approach for the oral administration of hydrophilic macromolecular drugs.

Lipids and polymers in pharmaceutical technology: Lifelong companions

In pharmaceutical technology, lipids and polymers are considered pillar excipients for the fabrication of most dosage forms, irrespective of the administration route. They play various roles ranging from support vehicles to release rate modifiers, stabilizers, solubilizers, permeation enhancers and transfection agents. Focusing on selected applications, which were discussed at the Annual Scientific Meeting of the Gattefossé Foundation 2018, this manuscript recapitulates the fundamental roles of these two important classes of excipients, either employed alone or in combination, and provides insight on their functional properties in various types of drug formulations. Emphasis is placed on oral formulations for the administration of active pharmaceutical ingredients with low aqueous solubilities or poor permeation properties. Additionally, this review article covers the use of lipids and polymers in the design of colloidal injectable delivery systems, and as substrates in additive manufacturing technologies for the production of tailor-made dosage forms.

Self-microemulsifying Drug Delivery System for Problematic Molecules: An Update

BACKGROUND

The poor bioavailability of a problematic molecule is predominantly due to its high lipophilicity, low solubility in gastric fluids and/or high fist pass metabolism. Self microemulsifying drug delivery system (SMEDDS), a lipidic type IV nano-formulation has been of interest in the field of pharmaceutical research due to its potential for tailoring the physicochemical properties of pharmaceutical molecules.

METHODS

This review provides insights on various recent innovations and reports from the past seven years (2012-2019) of self-emulsifying formulations for the delivery of various types of poorly soluble drugs, phytoconstituents and high molecular peptides and gives exhaustive details of the outcome of the endeavors in this field.

RESULTS

Various types of innovative formulations have been molded from SMEDDS like selfemulsifying powders, granules, tablets, pellets, eutectic and cationic formulations. Till date, many research reports and patents have been filed on self-emulsifying dosage forms and many formulations have gained US-FDA approvals which are summarized in the review article.

CONCLUSION

This review content highlighted the increasing scope of SMEDDS in augmenting the physiochemical properties of an API, the variegated formulation types and the attributes of API that can be improved by SMEDD based formulations.

Surface phosphorylation of nanoparticles by hexokinase: A powerful tool for cellular uptake improvement

The aim of the study was to develop zeta potential changing nanoparticles (NPs) via surface phosphorylation in order to improve their uptake by epithelial cells. Polymeric NPs were formed via in situ gelation between chitosan (CS) and chondroitin sulphate (ChS). Phosphorylation of these NPs was carried out by using hexokinase. The resulting phosphorylated NPs (p-NPs) were characterized in respect of their size and zeta potential. Phosphate release was quantified by incubating the particles with isolated as well as cell-associated intestinal alkaline phosphatase (AP). In parallel, resulting change in zeta potential was monitored. In-vitro mucus permeation of these particles was evaluated on porcine intestinal mucus. Furthermore, toxicity and cellular uptake studies were performed on Caco-2 cells. p-NPs exhibited a mean size of 412 ± 3.24 nm and a zeta potential of -12.4 mV. When these p-NPs were incubated with isolated as well as cell-associated AP, a significant amount of phosphate was released within 4 h and zeta potential raised up to -1.2 mV. p-NPs showed improved mucus permeation in comparison to unmodified NPs. Due to de-phosphorylation by AP, cellular uptake of p-NPs increased almost 2-fold. Moreover, particles displayed no toxicity. Findings of this study show that zeta potential changing p-NPs provide effective mucus permeation and enhanced cellular uptake.

Peptides as drug delivery vehicles across biological barriers

Peptides are small biological molecules that are attractive in drug delivery and materials engineering for applications including therapeutics, molecular building blocks and cell-targeting ligands. Peptides are small but can possess complexity and functionality as larger proteins. Due to their intrinsic properties, peptides are able to overcome the physiological and transport barriers presented by diseases. In this review, we discuss the progress of identifying and using peptides to shuttle across biological barriers and facilitate transport of drugs and drug delivery systems for improved therapy. Here, the focus of this review is on rationally designed, phage display peptides, and even endogenous peptides as carriers to penetrate biological barriers, specifically the blood-brain barrier(BBB), the gastrointestinal tract (GI), and the solid tumor microenvironment (T). We will discuss recent advances of peptides as drug carriers in these biological environments. From these findings, challenges and potential opportunities to iterate and improve peptide-based approaches will be discussed to translate their promise towards the clinic to deliver drugs for therapeutic efficacy.

Fluorescent and Photosensitizing Conjugates of Cell-Penetrating Peptide TAT(47-57): Design, Microwave-Assisted Synthesis at 60 °C, and Properties

Conjugates based on cell-penetrating peptides (CPPs) are scientifically relevant owing to their structural complexity; their ability to enter cells and deliver drugs, labels, antioxidants, bioactive compounds, or DNA fragments; and, consequently, their potential for application in research and biomedicine. In this study, carboxyamidated fluorescently labeled conjugates FAM-GG-TAT(47-57)-NH2 and FAM-PEG6-TAT(47-57)-NH2 and photosensitizer-labeled conjugate Chk-PEG6-TAT(47-57)-NH2 [where TAT(47-57) is the CPP, 5(6)-carboxyfluorescein is the (FAM) fluorophore, chlorin k (Chk) is the photosensitizer, and the dipeptide glycyl-glycine (GG) or hexaethylene glycol (PEG6) is the spacer] were originally designed, prepared, and fully characterized. Practically, all chemical reactions of the synthetic steps (peptide synthesis, spacer incorporation, and conjugation) were microwave-assisted at 60 °C using optimized protocols to give satisfying yields and high-quality products. Detailed analyses of the conjugates using spectrofluorimetry and singlet oxygen detection showed that they display photophysical properties typical of FAM or Chk. Anticandidal activity assays showed that not only this basic property of TAT(47-57) was preserved in the conjugates but also that the minimal inhibitory concentration was slightly reduced for cells incubated with PS-bearing conjugate Chk-PEG6-TAT(47-57)-NH2. Overall, these results indicated that the synthetic approach on-resin assisted by microwaves at 60 °C is simple, straightforward, selective, metal-free, sufficiently fast, cleaner, and more cost-effective than those previously used for preparing this type of macromolecule. Furthermore, such new data show that microwaves at 60 °C and/or conjugation did not harm the integrity of the conjugates' constituents. Therefore, FAM-GG-TAT(47-57)-NH2, FAM-PEG6-TAT(47-57)-NH2, and Chk-PEG6-TAT(47-57)-NH2 have high potential for practical applications in biochemistry, biophysics, and therapeutics.

Protease-functionalized mucus penetrating microparticles: In-vivo evidence for their potential

The focus of the current study was to explore whether immobilization of proteases to microparticles could result in their enhanced penetration into mucus. The proteases papain (PAP) and bromelain (BROM) were covalently attached to a polyacrylate (PAA; Carbopol 971P) via amide bond formation based on carbodiimide reaction. Microparticles containing these conjugates were generated via ionic gelation with calcium chloride and were characterized regarding size, surface charge, enzymatic activity and fluorescein diacetate (FDA) loading efficiency. Furthermore, mucus penetration potential of these microparticles was evaluated in-vitro on freshly collected porcine intestinal mucus, on intact intestinal mucosa and in-vivo in Sprague-Dawley rats. Results showed mean diameter of microparticles ranging between 2-3μm and surface charge between -8 to -18mV. The addition of PAA-microparticles to porcine intestinal mucus led to a 1.39-fold increase in dynamic viscosity whereas a 3.10- and 2.12-fold decrease was observed in case of PAA-PAP and PAA-BROM microparticles, respectively. Mucus penetration studies showed a 4.27- and 2.21- fold higher permeation of FDA loaded PAA-PAP and PAA-BROM microparticles as compared to PAA microparticles, respectively. Extent of mucus diffusion determined via silicon tube assay illustrated 3.96- fold higher penetration for PAA-PAP microparticles and 1.99- fold for PAA-BROM microparticles. An in-vitro analysis on porcine intestinal mucosa described up to 16- and 7.35-fold higher degree of retention and furthermore, during in-vivo evaluation in Sprague-Dawley rats a 3.35- and 2.07-fold higher penetration behavior was observed in small intestine for PAA-PAP and PAA-BROM microparticles as compared to PAA microparticles, respectively. According to these results, evidence for microparticles decorated with proteases in order to overcome the mucus barrier and to reach the absorption lining has been provided that offers wide ranging applications in mucosal drug delivery.

Zeta-potential-changing nanoparticles conjugated with cell-penetrating peptides for enhanced transfection efficiency

Aim: The aim of this study was to develop zeta-potential-changing nanoparticles (NPs) combining cell-penetrating peptides for gene delivery. Methods & materials: NPs were formed using phosphorylated carboxymethyl cellulose–glucosamine 6-phosphate (CMC–G6P) and polyethylene imine–polyarginine conjugates. Phosphate release was evaluated using intestinal alkaline phosphatase and cell lines. Transfection studies with plasmid DNA were then performed. Results: The zeta potential of CMC-G6P/branched PEI NPs was -3 mV and switched to +4 mV after intestinal alkaline phosphatase cleavage. The released phosphate in human colon adenocarcinoma cell line was more pronounced than human embryonic kidney cell line 293. Transfection studies demonstrated the greatest expression of plasmid DNA when being incorporated into CMC–G6P/polyethylene imine–polyarginine NPs. Conclusion: Novel zeta potential changing NPs combining cell-penetrating peptides are a promising tool to deliver DNA drugs to target cells.

Nanoemulsion: Concepts, development and applications in drug delivery

Nanoemulsions are biphasic dispersion of two immiscible liquids: either water in oil (W/O) or oil in water (O/W) droplets stabilized by an amphiphilic surfactant. These come across as ultrafine dispersions whose differential drug loading; viscoelastic as well as visual properties can cater to a wide range of functionalities including drug delivery. However there is still relatively narrow insight regarding development, manufacturing, fabrication and manipulation of nanoemulsions which primarily stems from the fact that conventional aspects of emulsion formation and stabilization only partially apply to nanoemulsions. This general deficiency sets up the premise for current review. We attempt to explore varying intricacies, excipients, manufacturing techniques and their underlying principles, production conditions, structural dynamics, prevalent destabilization mechanisms, and drug delivery applications of nanoemulsions to spike interest of those contemplating a foray in this field.

Nanocarriers protecting toward an intestinal pre-uptake metabolism

Pre-uptake metabolism within the GI tract is responsible for the poor oral bioavailability of numerous drugs. As nanocarriers function as a 'shield', protecting incorporated drugs from enzymatic attack, there is an increasing interest in utilizing them as a tool for overcoming drug degradation. Degradation of carriers resulting in the release of incorporated drugs, mucus permeation, enzyme inhibitory properties and their toxicity are crucial factors that must be taken into account when designing proper nanocarriers. The use of polymer- and lipid-based nanocarriers as protective vehicles are discussed within this review. Lipid-based carriers and novel mucopenetrating particles seem to have a great potential in avoiding metabolizing enzymes. Accordingly, nanocarriers are promising tools for improving the bioavailability of drugs, being sensitive to a pre-uptake metabolism.

Lipid-based nanocarriers for the oral administration of biopharmaceutics

Biopharmaceutics have been recognized as the drugs of choice for the treatment of several diseases, mainly due to their high selectivity and potent action. Nonetheless, their oral administration is a rather challenging problem, since their bioavailability is significantly hindered by various physiological barriers along the GI tract, including their acid-induced hydrolysis in the stomach, their enzymatic degradation throughout the GI tract and their poor mucosa permeability. Lipid-based nanocarriers represent a viable means for enhancing the oral bioavailability of biomolecules while diminishing toxicity-related issues. The present review describes the main physiological barriers limiting the oral bioavailability of macromolecules and highlights recent advances in the field of lipid-based carriers as well as the respective lipid intestinal absorption mechanisms.