Role of self-emulsifying drug delivery systems in optimizing the oral delivery of hydrophilic macromolecules and reducing interindividual variability

Enhancing oral bioavailability of Ca-DTPA by self double emulsifying drug delivery system (SDEDDS)

OBJECTIVE

BCS class III drug (highly soluble, poorly permeable) possesses low oral bioavailability. The research work highlights the utility of self-double emulsifying drug delivery system (SDEDDS) which are stable isotropic mixture of w/o primary emulsion and hydrophilic surfactants for improving oral bioavailability of Ca-DTPA (Calcium diethylenetriamine pentaacetate). Upon oral administration, SDEDDS rapidly emulsifies into w/o/w double emulsions in the aqueous gastrointestinal environment, with hydrophilic drugs entrapped inside oil reservoirs.

METHODS

SDEDDS formulation was successfully developed using excipients, that is, medium chain triglycerides, oleic acid, phospholipids, Span 80, Tween 80 using double emulsification technique.

RESULTS

The optimized formulation F4 (Aq. phase: 11.6%w,w; MCT & oleic acid: 70.9%w/w; Span 80:17.5%w/w; Lecithin:16%w/w and Tween 80 (10%w/w)) appeared bright yellow liquid which upon dilution appeared milky white within 2 min, droplet size (501.7 nm), pdi value (0.044), zeta potential (-52 mV), entrapment efficiency (79.6 ± 1.63), viscosity (72.2 ± 1.8 mpA.s), significant high cumulative in vitro drug permeation (CDP) and 2.17-fold increase in apparent permeability coefficient. Pharmacokinetic studies in rats showed 1.17-fold increases in AUC of F4 and comparatively higher plasma levels (Cmax) compared with pure drug administered orally. The Absolute (OF4, OD) and Relative bioavailability was found to be 14.52%, 12.35%, and 117.47%, respectively.

CONCLUSION

The present studies have clearly demonstrated that SDEDDS could readily form w/o/w double emulsions in vivo with enhanced in vitro and in vivo oral bioavailability. Therefore, considerable augmentation in the rate and extent of oral drug absorption ratified the better performance of the SDEDDS in enhancing the bioavailability of Ca-DTPA.

Electrospun Nanofibers: Shaping the Future of Controlled and Responsive Drug Delivery

Electrospun nanofibers for drug delivery systems (DDS) introduce a revolutionary means of administering pharmaceuticals, holding promise for both improved drug efficacy and reduced side effects. These biopolymer nanofiber membranes, distinguished by their high surface area-to-volume ratio, biocompatibility, and biodegradability, are ideally suited for pharmaceutical and biomedical applications. One of their standout attributes is the capability to offer the controlled release of the active pharmaceutical ingredient (API), allowing custom-tailored release profiles to address specific diseases and administration routes. Moreover, stimuli-responsive electrospun DDS can adapt to conditions at the drug target, enhancing the precision and selectivity of drug delivery. Such localized API delivery paves the way for superior therapeutic efficiency while diminishing the risk of side effects and systemic toxicity. Electrospun nanofibers can foster better patient compliance and enhanced clinical outcomes by amplifying the therapeutic efficiency of routinely prescribed medications. This review delves into the design principles and techniques central to achieving controlled API release using electrospun membranes. The advanced drug release mechanisms of electrospun DDS highlighted in this review illustrate their versatility and potential to improve the efficacy of medical treatments.

The Development of Dermal Self-Double-Emulsifying Drug Delivery Systems: Preformulation Studies as the Keys to Success

Self-emulsifying drug delivery systems (SEDDSs) are lipid-based systems that are superior to other lipid-based oral drug delivery systems in terms of providing drug protection against the gastrointestinal (GI) environment, inhibition of drug efflux as mediated by P-glycoprotein, enhanced lymphatic drug uptake, improved control over plasma concentration profiles of drugs, enhanced stability, and drug loading efficiency. Interest in dermal spontaneous emulsions has increased, given that systems have been reported to deliver drugs across mucus membranes, as well as the outermost layer of the skin into the underlying layers. The background and development of a double spontaneous emulsion incorporating four anti-tubercular drugs, clofazimine (CFZ), isoniazid (INH), pyrazinamide (PZY), and rifampicin (RIF), are described here. Our methods involved examination of oil miscibility, the construction of pseudoternary phase diagrams, the determination of self-emulsification performance and the emulsion stability index of primary emulsions (PEs), solubility, and isothermal micro calorimetry compatibility and examination of emulsions via microscopy. Overall, the potential of self-double-emulsifying drug delivery systems (SDEDDSs) as a dermal drug delivery vehicle is now demonstrated. The key to success here is the conduct of preformulation studies to enable the development of dermal SDEDDSs. To our knowledge, this work represents the first successful example of the production of SDEDDSs capable of incorporating four individual drugs.

Challenges and opportunities in delivering oral peptides and proteins

INTRODUCTION

Rapid advances in bioengineering enable the use of complex proteins as therapeutic agents to treat diseases. Compared with conventional small molecule drugs, proteins have multiple advantages, including high bioactivity and specificity with low toxicity. Developing oral dosage forms with active proteins is a route to improve patient compliance and significantly reduce production costs. However, the gastrointestinal environment remains a challenge to this delivery path due to enzymatic degradation, low permeability, and weak absorption, leading to reduced delivery efficiency and poor clinical outcomes.

AREAS COVERED

This review describes the barriers to oral delivery of peptides and complex proteins, current oral delivery strategies utilized and the opportunities and challenges ahead to try and circumvent these barriers. Oral protein drugs on the market and clinical trials provide insights and approaches for advancing delivery strategies.

EXPERT OPINION

Although most current studies on oral protein delivery rely on in vitro and in vivo animal data, the safety and limitations of the approach in humans remain uncertain. The shortage of clinical data limits the development of new or alternative strategies. Therefore, designing appropriate oral delivery strategies remains a significant challenge and requires new ideas, innovative design strategies and novel model systems.

Hydrophobic ion pairing-based self-emulsifying drug delivery systems: a new strategy for improving the therapeutic efficacy of water-soluble drugs

INTRODUCTION

Self-emulsifying drug delivery systems (SEDDS) are formulations consisting of oil phase, emulsifiers, and co-emulsifiers, which can be spontaneously emulsified in the body to form O/W microemulsion. Traditionally, SEDDS are used commercially for the improvement of oral absorption and in vivo performances for poorly water-soluble drugs. However, SEDDS formulations were rarely reported for the delivery of water-soluble drugs. Recent studies have found that SEDDS have the potential for water-soluble macromolecular drugs by the application of the hydrophobic ion pairing (HIP) technology.

AREAS COVERED

This review summarized the characteristics of HIP complexes in SEDDS and introduced their advantages and discussed the future prospects of HIP-based SEDDS in drug delivery.

EXPERT OPINION

Hydrophobic ion pairing (HIP) is a technology that combines lipophilic structures on polar counterions to increase the lipophilicity through electrostatic interaction. Recent studies showed that HIP-based SEDDS offer an effective way to increase the mucosal permeability and improve the chemical stability for antibiotics, proteases, DNA-based drugs, and other water-soluble macromolecular drugs. It is believed that HIP-based SEDDS offer a potential and attractive method capable of delivering hydrophilic macromolecules with ionizable groups for oral administration.

Nanocarrier system: An emerging strategy for bioactive peptide delivery

Compared with small-molecule synthetic drugs, bioactive peptides have desirable advantages in efficiency, selectivity, safety, tolerance, and side effects, which are accepted by attracting extensive attention from researchers in food, medicine, and other fields. However, unacceptable barriers, including mucus barrier, digestive enzyme barrier, and epithelial barrier, cause the weakening or the loss of bioavailability and biostability of bioactive peptides. The nanocarrier system for bioactive peptide delivery needs to be further probed. We provide a comprehensive update on the application of versatile delivery systems for embedding bioactive peptides, including liposomes, polymer nanoparticles, polysaccharides, hydrogels, and self-emulsifying delivery systems, and further clarify their structural characterization, advantages, and disadvantages as delivery systems. It aims to provide a reference for the maximum utilization of bioactive peptides. It is expected to be an effective strategy for improving the bioavailability and biostability of bioactive peptides.

Preparation and Characterization of Pazopanib Hydrochloride-Loaded Four-Component Self-Nanoemulsifying Drug Delivery Systems Preconcentrate for Enhanced Solubility and Dissolution

The aim of this study was to develop a four-component self-nanoemulsifying drug delivery system (FCS) to enhance the solubility and dissolution of pazopanib hydrochloride (PZH). In the solubility test, PZH showed a highly pH-dependent solubility (pH 1.2 > water >> pH 4.0 and pH 6.8) and was solubilized at 70 °C in the order Kollisolv PG (5.38%, w/w) > Kolliphor RH40 (0.49%) > Capmul MCM C10 (0.21%) and Capmul MCM C8 (0.19%), selected as the solubilizer, the surfactant, and the oils, respectively. In the characterization of the three-component SNEDDS (TCS) containing Kolliphor RH40/Capmul MCM C10, the particle size of dispersion was very small (<50 nm) and the PZH loading was 0.5% at the weight ratio of 9/1. In the characterization of FCS containing additional Kollisolv PG to TCS, PZH loading was increased to 5.30% without any PZH precipitation, which was 10-fold higher compared to the TCS. The optimized FCS prepared with the selected formulation (Kolliphor RH40/Capmul MCM C10/Kollisolv PG) showed a consistently complete and high dissolution rate (>95% at 120 min) at four different pHs with 1% polysorbate 80, whereas the raw PZH and Kollisolv PG solution showed a pH-dependent poor dissolution rate (about 40% at 120 min), specifically at pH 6.8 with 1% polysorbate 80. In conclusion, PZH-loaded FCS in this work demonstrated enhanced solubility and a consistent dissolution rate regardless of medium pH.

Fast-Fed Variability: Insights into Drug Delivery, Molecular Manifestations, and Regulatory Aspects

Among various drug administration routes, oral drug delivery is preferred and is considered patient-friendly; hence, most of the marketed drugs are available as conventional tablets or capsules. In such cases, the administration of drugs with or without food has tremendous importance on the bioavailability of the drugs. The presence of food may increase (positive effect) or decrease (negative effect) the bioavailability of the drug. Such a positive or negative effect is undesirable since it makes dosage estimation difficult in several diseases. This may lead to an increased propensity for adverse effects of drugs when a positive food effect is perceived. However, a negative food effect may lead to therapeutic insufficiency for patients suffering from life-threatening disorders. This review emphasizes the causes of food effects, formulation strategies to overcome the fast-fed variability, and the regulatory aspects of drugs with food effects, which may open new avenues for researchers to design products that may help to eliminate fast-fed variability.

Self-Emulsifying Drug Delivery Systems: An Alternative Approach to Improve Brain Bioavailability of Poorly Water-Soluble Drugs through Intranasal Administration

Efforts in discovering new and effective neurotherapeutics are made daily, although most fail to reach clinical trials. The main reason is their poor bioavailability, related to poor aqueous solubility, limited permeability through biological membranes, and the hepatic first-pass metabolism. Nevertheless, crossing the blood–brain barrier is the major drawback associated with brain drug delivery. To overcome it, intranasal administration has become more attractive, in some cases even surpassing the oral route. The unique anatomical features of the nasal cavity allow partial direct drug delivery to the brain, circumventing the blood–brain barrier. Systemic absorption through the nasal cavity also avoids the hepatic first-pass metabolism, increasing the systemic bioavailability of highly metabolized entities. Nevertheless, most neurotherapeutics present physicochemical characteristics that require them to be formulated in lipidic nanosystems as self-emulsifying drug delivery systems (SEDDS). These are isotropic mixtures of oils, surfactants, and co-surfactants that, after aqueous dilution, generate micro or nanoemulsions loading high concentrations of lipophilic drugs. SEDDS should overcome drug precipitation in absorption sites, increase their permeation through absorptive membranes, and enhance the stability of labile drugs against enzymatic activity. Thus, combining the advantages of SEDDS and those of the intranasal route for brain delivery, an increase in drugs’ brain targeting and bioavailability could be expected. This review deeply characterizes SEDDS as a lipidic nanosystem, gathering important information regarding the mechanisms associated with the intranasal delivery of drugs loaded in SEDDS. In the end, in vivo results after SEDDS intranasal or oral administration are discussed, globally revealing their efficacy in comparison with common solutions or suspensions.

Insights into the release mechanisms of antioxidants from nanoemulsion droplets

The therapeutic effects of antioxidant-loaded nanoemulsion can be often optimized by controlling the release rate in human body. Release kinetic models can be used to predict the release profile of antioxidant compounds and allow identification of key parameters that affect the release rate. It is known that one of the critical aspects in establishing a reliable release kinetic model is to understand the underlying release mechanisms. Presently, the underlying release mechanisms of antioxidants from nanoemulsion droplets are not yet fully understood. In this context, this review scrutinized the current formulation strategies to encapsulate antioxidant compounds and provide an outlook into the future of this research area by elucidating possible release mechanisms of antioxidant compounds from nanoemulsion system.

Design and Development of Solid SMEDDS and Liquisolid Formulations of Lovastatin, for Improved Drug Dissolution and In vivo Effects-a Pharmacokinetic and Pharmacodynamic Assessment

Lovastatin (Lov) is a lipid-lowering agent, with 5% bioavailability (BA) due to extensive first pass metabolism and poor solubility. To enhance dissolution and in vivo effects, Lov solid self microemulsifying drug delivery system (SMEDDS) and liquisolid systems were developed and evaluated to select superior one. Solubilities were determined in oils, surfactants, and cosurfactants. Ternary phase diagrams were constructed and selected the one which showed maximum emulsion zone. In vitro dissolution, DSC, SEM and PXRD studies were used to characterize the developed formulations. In vivo studies were conducted on optimal formulations in wistar rats. Based on solubilities, Capmul PG8 and Capmul MCM were preferred as oils, Labrasol and Transcutol P as surfactant and cosurfactant. Here, Syloid XDP carrier showed better adsorption capacity among others, hence was used in optimal solid SMEDDS (SX) and liquisolid (LS) formulations. Dissolution study results showed significant improvement in release when compared to pure drug. DSC, SEM, and PXRD results indicated the loss of drug crystallinity in optimal formulations. In pharmacokinetic (PK) study, SX and LS showed 2.57 and 1.43 fold improvements in AUC, when compared to that of coarse suspension (CS). In pharmacodynamic (PD) study, hyperlipidemia was induced by Triton X-100. CS and LS treatments showed a decline in hyperlipidemic levels at 4 h. But, SX-treated group showed early onset of decline at 2 h. Further, the duration of anti-hyperlipidemia was at least 12 h extra when compared to CS and LS. This study confirmed the superiority of SX over LS in PK and PD effects.

Progress and limitations of oral peptide delivery as a potentially transformative therapy

INTRODUCTION

The oral delivery of peptides offers advantages over the injectable route of administration due to patient convenience. However, oral delivery remains challenging due to physiological barriers. Numerous formulation technologies have been developed to overcome these challenges, and understanding the advantages and limitations of each technology is important for the development of new delivery systems to enable oral delivery of peptides designed for parenteral administration.

AREAS COVERED

This review summarizes key learnings from the use of permeation enhancers (PEs) for oral peptide delivery associated with solid dosage form optimization to maximize the PE effect. Furthermore, we will highlight the most recent emerging delivery strategies to improve oral peptide bioavailability such as nanoparticles, self-emulsifying drug delivery systems, gut shuttles, and ingestible devices. In addition, advantages and limitations of these technologies will be compared with the permeation enhancer technology.

EXPERT OPINION

Despite the success of permeation enhancer technology in the FDA approved oral peptide products for gastric and intestinal delivery, oral peptide delivery is still facing the immense challenge of low-to-single digit oral bioavailability and the impact of food and water intake on oral absorption. Optimization of drug product attributes such as dissolution kinetics is critical to overcome spreading and dilution effects in vivo to improve permeation enhancer efficacy. The next frontiers to substantially increase oral bioavailability and transform injectable peptides to oral deliverables may be ingestible devices and gut shuttles. In addition, ingestible devices may have potential to overcome the impact of food on oral bioavailability. However, clinical studies are necessary to inform the safety and efficacy of these emerging technologies.

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.

Targeting Neuroimmune Interactions in Diabetic Neuropathy with Nanomedicine

Significance: Diabetes is a major source of neuropathy and neuropathic pain that is set to continue growing in prevalence. Diabetic peripheral neuropathy (DPN) and pain associated with diabetes are not adequately managed by current treatment regimens. Perhaps the greatest difficulty in treating DPN is the complex pathophysiology, which involves aspects of metabolic disruption and neurotrophic deficits, along with neuroimmune interactions. There is, therefore, an urgent need to pursue novel therapeutic options targeting the key cellular and molecular players. Recent Advances: To that end, cellular targeting becomes an increasingly compelling drug delivery option as our knowledge of neuroimmune interactions continues to mount. These nanomedicine-based approaches afford a potentially unparalleled specificity and longevity of drug targeting, using novel or established compounds, all while minimizing off-target effects. Critical Issues: The DPN therapeutics directly targeted at the nervous system make up the bulk of currently available treatment options. However, there are significant opportunities based on the targeting of non-neuronal cells and neuroimmune interactions in DPN. Future Directions: Nanomedicine-based agents represent an exciting opportunity for the treatment of DPN with the goals of improving the efficacy and safety profile of analgesia, as well as restoring peripheral neuroregenerative capacity. Antioxid. Redox Signal. 36, 122-143.

New potential application of hydroxypropyl-β-cyclodextrin in solid self-nanoemulsifying drug delivery system and solid dispersion

The purpose of this study was to use hydroxypropyl-β-cyclodextrin (HP-β-CD) as a novel carrier in solid SNEDDS and solid dispersions to enhance the solubility and oral bioavailability of poorly water-soluble dexibuprofen. The novel dexibuprofen-loaded solid SNEDDS was composed of dexibuprofen, corn oil, polysorbate 80, Cremophor® EL, and HP-β-CD at a weight ratio of 45/35/50/15/100. This solid SNEDDS spontaneously formed a nano-emulsion with a size of approximately 120 nm. Unlike the conventional solid SNEDDS prepared with colloidal silica as a carrier, this dexibuprofen-loaded solid SNEDDS exhibited a spherical structure. Similar to the dexibuprofen-loaded solid dispersion prepared with HP-β-CD, the transformation of the crystalline drug to an amorphous state with no molecular interactions were observed in the solid SNEDDS. Compared to the solid dispersion and dexibuprofen powder, solid SNEDDS significantly enhanced drug solubility and AUC. Therefore, HP-β-CD is a novel potential carrier in SNEDDS for improving the oral bioavailability of dexibuprofen.

Hydrophobic ion-pairing assembled liposomal Rhein with efficient loading for acute pancreatitis treatment

AIM

The present study aimed to develop liposomal Rhein by employing a hydrophobic ion-pairing technique (HIP) for improved pancreatitis therapy.

METHODS

F127 modified liposomal Rhein (F127-RPC-Lip) was prepared using a two-step process consisting of complexation first, followed by a film-ultrasonic dispersion step. The drug-phospholipid interaction was characterised by FT-IR and P-XRD. Particle size and morphology were investigated using DLS and TEM, respectively. Biodistribution and therapeutic efficacy of F127-RPC-Lip were evaluated in a rat model of acute pancreatitis.

RESULTS

F127-RPC-Lip achieved efficient drug encapsulation after complexation with lipids through non-covalent interactions and had an average hydrodynamic diameter of about 141 nm. F127-RPC-Lip demonstrated slower drug release (55.90 ± 3.60%, w/w) than Rhein solution (90.27 ± 5.11%) within 24 h. Compared with Rhein, F127-RPC-Lip exhibited prolonged systemic circulation time, superior drug distribution, and attenuated injury in the pancreas of rats post-injection.

CONCLUSIONS

HIP-assembled liposomes are a promising strategy for Rhein in treating pancreatitis.

Polymer-Based Dual-Responsive Self-Emulsifying Nanodroplets as Potential Carriers for Poorly Soluble Drugs

A biodegradable amphiphilic liquid polymer was designed to form self-emulsifying nanodroplets in water for delivering poorly soluble drugs. The polymer was composed of multiple short blocks of poly(ethylene glycol) (PEG) and poly(caprolactone) (PCL) connected through acid-labile acetal linkages. With an overall average molecular weight of over 18 kDa, the polymer remained as a viscous liquid under room and physiological temperatures. Dispersing the polymer in an aqueous buffer gave rise to highly stable micelle-like nanodroplets with an average size of approximately 15-20 nm. The nanodroplet dispersions underwent reversible temperature-sensitive aggregation with cloud points ranging from 45 to 50 °C, depending on polymer concentration. Nuclear magnetic resonance (NMR) and dynamic light scattering analyses revealed that while the nanodroplets were stable at pH 7.4 for several days, hydrolysis of the acetal linkages in the polymer backbone was much accelerated under mildly acidic pH 5.0, resulting in the formation of large microdroplets. Nile red (NR), a poorly water-soluble fluorophore, can be solubilized in the nanodroplets, and efficient intracellular delivery of NR was achieved. The hydrophobic indocyanine green (ICG) was also encapsulated in the nanodroplets. Near-infrared (NIR) fluorescence imaging and in vivo biocompatibility of the ICG-loaded nanodroplets were demonstrated in mice. In summary, the self-emulsifying nanodroplets of amphiphilic liquid polymer would be a promising material system for poorly soluble drug delivery and imaging in vivo.

Challenges of peptide and protein drug delivery by oral route: Current strategies to improve the bioavailability

Advancement in biotechnology provided a notable expansion of peptide and protein therapeutics, used as antigens, vaccines, hormones. It has a prodigious potential to treat a broad spectrum of diseases such as cancer, metabolic disorders, bone disorders, and so forth. Protein and peptide therapeutics are administered parenterally due to their poor bioavailability and stability, restricting their use. Hence, research focuses on the oral delivery of peptides and proteins for the ease of self-administration. In the present review, we first address the main obstacles in the oral delivery system in addition to approaches used to enhance the stability and bioavailability of peptide/protein. We describe the physiochemical parameters of the peptides and proteins influencing bioavailability in the systemic circulation. It encounters, many barriers affecting its stability, such as poor cellular membrane permeability at the GIT site, enzymatic degradation (various proteases), and first-pass hepatic metabolism. Then describe the current approaches to overcome the challenges mentioned above by the use of absorption enhancers or carriers, structural modification, formulation and advance technology.

Novel formulations and drug delivery systems to administer biological solids

Recent advances in formulation sciences have expanded the previously limited design space for biological modalities, including peptide, protein, and vaccine products. At the same time, the discovery and application of new modalities, such as cellular therapies and gene therapies, have presented formidable challenges to formulation scientists. We explore these challenges and highlight the opportunities to overcome them through the development of novel formulations and drug delivery systems as biological solids. We review the current progress in both industry and academic laboratories, and we provide expert perspectives in those settings. Formulation scientists have made a tremendous effort to accommodate the needs of these novel delivery routes. These include stability-preserving formulations and dehydration processes as well as dosing regimes and dosage forms that improve patient compliance.

Zeta potential changing nanoemulsions based on a simple zwitterion

HYPOTHESIS

Simple zwitterions used as auxiliary agents might have the potential to change the zeta potential of oil-in-water (o/w) nanoemulsions on the mucosa.

EXPERIMENTS

The zwitterion phosphorylated tyramine (p-Tyr) was synthesized by phosphorylation of Boc-tyramine (Boc-Tyr) using phosphoryl chloride (POCl3). It was incorporated with 2% (m/v) in a self-emulsifying lipophilic phase comprising Captex 35, Cremophor EL, Capmul MCM and glycerol 85 at a ratio of 30:30:30:10 v/v. Phosphate release and resulting change in zeta potential were evaluated by incubating p-Tyr containing nanoemulsion with isolated intestinal alkaline phosphatase (AP). Mucus permeating behavior was evaluated across mucus obtained from porcine small intestinal mucosa. Subsequently, cellular uptake studies were accomplished on Caco-2 cells.

FINDINGS

The p-Tyr loaded nanoemulsion exhibited a mean droplet size of 43 ± 1.7 nm and zeta potential of -8.40 mV. Phosphate moieties were rapidly cleaved from p-Tyr loaded nanoemulsions after incubation with isolated AP resulting in a shift in zeta potential from -8.40 mV to +1.2 mV. p-Tyr loaded nanoemulsion revealed a significantly (p ≤ 0.001) improved mucus permeation compared to the same nanoemulsion having been pre-treated with AP. Cellular uptake of the zeta potential changing oily droplets was 2.4-fold improved. Phosphorylated zwitterions seem to be an alternative to cationic surfactants and considered as promising auxiliary agents for zeta potential changing nanoemulsions.

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.

Protection of Protein Drugs by Self-Emulsified Nanoemulsion Against Proteolysis

The present study aimed to develop a self-emulsified nanoemulsion for salmon calcitonin (sCT) for non-invasive delivery. Hydrophobic ion pairing method was used to form hydrophobic complex of sCT with 4 counter ions (oleate, deoxycholate, docusate and tripolyphosphate). The partition coefficient and dissociation of the complexes in water of various pH were investigated. The complex-loaded nanoemulsions were characterized for droplet size, leakage of sCT from the droplets, and protection of sCT from enzymatic degradation. The results show that all the counter ions could form complexes with sCT with a complexation efficiency about 95% at pH 8.0. The complexes significantly increased the partition coefficient of sCT. The dissociation of the complexes in water was pH-dependent. At pH 6.8 and 7.4, the dissociation was negligible. At pH 1.0, the dissociation was 71%, 8%, 37% and 50% for sCT-polyphosphate, sCT-docusate, sCT-oleate and sCT-deoxycholate, respectively. The developed nanoemulsions had a size in the range of 27-62 nm. The leakage of sCT from the nanodroplets into the aqueous phase depended on the lipophilicity of the counter ions: 60%, 56%, and 24% leakage for sCT-docusate, sCT-oleate and sCT-deoxycholate, respectively. The nanoemulsion protected sCT from enzyme degradation when loaded inside the droplets, but not the leaked sCT.

Development of Topical/Transdermal Self-Emulsifying Drug Delivery Systems, Not as Simple as Expected

Self-emulsifying drug delivery systems (SEDDSs) originated as an oral lipid-based drug delivery system with the sole purpose of improving delivery of highly lipophilic drugs. However, the revolutionary drug delivery possibilities presented by these uniquely simplified systems in terms of muco-adhesiveness and zeta-potential changing capacity lead the way forward to ground-breaking research. Contrarily, SEDDSs destined for topical/transdermal drug delivery have received limited attention. Therefore, this review is focused at utilising principles, established during development of oral SEDDSs, and tailoring them to fit evaluation strategies for an optimised topical/transdermal drug delivery vehicle. This includes a detailed discussion of how the authentic pseudo-ternary phase diagram is employed to predict phase behaviour to find the self-emulsification region most suitable for formulating topical/transdermal SEDDSs. Additionally, special attention is given to the manner of characterising oral SEDDSs compared to topical/transdermal SEDDSs, since absorption within the gastrointestinal tract and the multi-layered nature of the skin are two completely diverse drug delivery territories. Despite the advantages of the topical/transdermal drug administration route, certain challenges such as the relatively undiscovered field of skin metabolomics as well as the obstacles of choosing excipients wisely to establish skin penetration enhancement might prevail. Therefore, development of topical/transdermal SEDDSs might be more complicated than expected.

Recent Advances in Encapsulation, Protection, and Oral Delivery of Bioactive Proteins and Peptides using Colloidal Systems

There are many areas in medicine and industry where it would be advantageous to orally deliver bioactive proteins and peptides (BPPs), including ACE inhibitors, antimicrobials, antioxidants, hormones, enzymes, and vaccines. A major challenge in this area is that many BPPs degrade during storage of the product or during passage through the human gut, thereby losing their activity. Moreover, many BPPs have undesirable taste profiles (such as bitterness or astringency), which makes them unpleasant to consume. These challenges can often be overcome by encapsulating them within colloidal particles that protect them from any adverse conditions in their environment, but then release them at the desired site-of-action, which may be inside the gut or body. This article begins with a discussion of BPP characteristics and the hurdles involved in their delivery. It then highlights the characteristics of colloidal particles that can be manipulated to create effective BPP-delivery systems, including particle composition, size, and interfacial properties. The factors impacting the functional performance of colloidal delivery systems are then highlighted, including their loading capacity, encapsulation efficiency, protective properties, retention/release properties, and stability. Different kinds of colloidal delivery systems suitable for encapsulation of BPPs are then reviewed, such as microemulsions, emulsions, solid lipid particles, liposomes, and microgels. Finally, some examples of the use of colloidal delivery systems for delivery of specific BPPs are given, including hormones, enzymes, vaccines, antimicrobials, and ACE inhibitors. An emphasis is on the development of food-grade colloidal delivery systems, which could be used in functional or medical food applications. The knowledge presented should facilitate the design of more effective vehicles for the oral delivery of bioactive proteins and peptides.

Self-microemulsifying drug delivery systems of Moringa oleifera extract for enhanced dissolution of kaempferol and quercetin

The aim of the present study was to develop self-microemulsifying drug delivery systems (SMEDDS) of the extract of Moringa oleifera, a herbal medicinal plant. Kaempferol and quercetin, the flavonoids present in the leaf extract of M. oleifera, were chosen as markers for quantification. The optimized formulation of SMEDDS consisted of propylene glycol dicaprylocaprate, polysorbate 80, and polyethylene glycol 400 (PEG 400) in a percentage ratio of 20:60:20 (m/m). SMEDDS emulsified immediately (within 20 s) after dilution in water, resulting in transparent microemulsions with a droplet size of 49 nm. SMEDDS could increase the solubility of kaempferol and quercetin to nearly 100 % within 15 min, whereas only a 30 % improvement in solubility was achieved in the case of crude extract. These results demonstrated SMEDDS to be a promising strategy to improve the solubility of M. oleifera extract-derived drugs, which, in turn, could prove beneficial to the herbal medicine field.

Improvement of Peptide Affinity and Stability by Complexing to Cyclodextrin-Grafted Ammonium Chitosan

Cyclodextrin-grafted polymers are attractive biomaterials that could bring together the host–guest complexing capability of pristine cyclodextrin and the pharmaceutical features of the polymeric backbone. The present paper is aimed at characterizing the potential application of ammonium–chitosan grafted with 2-methyl-β-cyclodextrin (N⁺-rCh-MCD) as the functional macromolecular complexing agent for the oral administration of the neuropeptide dalargin (DAL). Specific NMR characterization procedures, along with UV and fluorescence techniques, as well as biological in vitro assessments have been performed. The results indicate that N⁺-rCh-MCD forms water-soluble complexes with DAL, with a prevalent involvement of Tyr or Phe over Leu and Ala residues. The association constant of DAL with the polymeric derivative is one order of magnitude higher than that with the pristine cyclodextrin (K_a: 2600 M⁻¹ and 120 M⁻¹, respectively). Additionally, N⁺-rCh-MCD shields DAL from enzymatic degradation in gastrointestinal in vitro models with a three-fold time delay, suggesting a future pharmaceutical exploitation of the polymeric derivative. Therefore, the greater affinity of N⁺-rCh-MCD for DAL and its protective effect against enzymatic hydrolysis can be attributed to the synergistic cooperation between cyclodextrin and the polymer, which is realized only when the former is covalently linked to the latter.

Recent Advancements in Using Polymers for Intestinal Mucoadhesion and Mucopenetration

Oral administration of actives is the most desired form of delivery, but the formulations need to overcome a variety of barriers including the intestinal mucus. This feature article summarizes the developments from the past 2-3 years in this context focusing on polymer-based formulations. The progress in assembling mucopenetrating nanoparticles is outlined considering coatings using noninteracting polymers as well as virus-like particles and charge-shifting particles. Next, polymers and their modification to enhance mucoadhesion are discussed, followed by providing examples of double-encapsulation systems that aim to combine mucopenetration with mucoadhesion in the same formulation. Finally, a short outlook is provided highlighting a few of the most pressing challenges to address.

Mechanisms of oral absorption improvement for insoluble drugs by the combination of phospholipid complex and SNEDDS

In the present study, a water insoluble drug named silybin was encapsulated into self-nanoemulsifying drug delivery system (SNEDDS) following the preparation of silybin-phospholipid complex (SB-PC), then several methods were carried out to characterize SB-PC-SNEDDS and elucidate its mechanisms to improve the oral absorption of SB. Using a dynamic in vitro digestion model, the lipolysis of SB-PC-SNEDDS was proved to be mainly related with the property of its lipid excipients. SB-PC-SNEDDS could significantly enhance the transport of SB across Caco-2 cells, which may partly attribute to the increased cell membrane fluidity and the loss of tight junction according to the analysis results of fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH) and tight junction protein (ZO-1). The result of in situ perfusion showed the intestinal absorption of SB from high to low was SB-PC-SNEDDS, SB-PC, and SB. The extent of lymphatic transport of SB-PC and SB-PC-SNEDDS via the mesenteric duct was 12.2 and 22.7 folds of that of SB, respectively. In the lymph duct cannulated rats, the relative bioavailability (Fr) of SB-PC and SB-PC-SEDDS compared to SB was 1265.9% and 1802.5%, respectively. All the above results provided mechanistic support for oral absorption improvement of water insoluble drugs by the combination of PC and SNEDDS.

Rivaroxaban polymeric amorphous solid dispersions: Moisture-induced thermodynamic phase behavior and intermolecular interactions

The present study evaluates the physical stability and intermolecular interactions of Rivaroxaban (RXB) amorphous solid dispersions (ASDs) in polymeric carriers via thermodynamic modelling and molecular simulations. Specifically, the Flory-Huggins (FH) lattice solution theory was used to construct thermodynamic phase diagrams of RXB ASDs in four commonly used polymeric carriers (i.e. copovidone, coPVP, povidone, PVP, Soluplus, SOL and hypromellose acetate succinate, HPMCAS), which were stored under 0%, 60% and 75% relative humidity (RH) conditions. In order to verify the phase boundaries predicted by FH modelling (i.e. truly amorphous zone, amorphous-amorphous demixing zones and amorphous-API recrystallization zones), samples of ASDs were examined via polarized light microscopy after storage for up to six months at various RH conditions. Results showed a good agreement between the theoretical and the experimental approaches (i.e. coPVP and PVP resulted in less physically-stable ASDs compared to SOL and HPMCAS) indicating that the proposed FH-based modelling may be a useful tool in predicting long-term physical stability in high humidity conditions. In addition, molecular dynamics (MD) simulations were employed in order to interpret the observed differences in physical stability. Results, which were verified via differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), suggested the formation of similar intermolecular interactions in all cases, indicating that the interaction with moisture water plays a more crucial role in ASD physical stability compared to the formation of intermolecular interactions between ASD components.

Oral absorption and lymphatic transport of baicalein following drug-phospholipid complex incorporation in self-microemulsifying drug delivery systems

PURPOSE

The aims of this study were to prepare a baicalein self-microemulsion with baicalein-phospholipid complex as the intermediate (BAPC-SMEDDS) and to compare its effects with those of conventional baicalein self-microemulsion (CBA-SMEDDS) on baicalein oral absorption and lymphatic transport.

METHODS

Two SMEDDS were characterized by emulsifying efficiency, droplet size, zeta potential, cloud point, dilution stability, physical stability, and in vitro release and lipolysis. Different formulations of 40 mg/kg baicalein were orally administered to Sprague-Dawley rats to investigate their respective bioavailabilities. The chylomicron flow blocking rat model was used to evaluate their lymphatic transport.

RESULTS

The droplet sizes of BAPC-SMEDDS and CBA-SMEDDS after 100x dilution were 9.6±0.2 nm and 11.3±0.4 nm, respectively. In vivo experiments indicated that the relative bioavailability of CBA-SMEDDS and BAPC-SMEDDS was 342.5% and 448.7% compared to that of free baicalein (BA). The AUC0-t and Cmax of BAPC-SMEDDS were 1.31 and 1.87 times higher than those of CBA-SMEDDS, respectively. The lymphatic transport study revealed that 81.2% of orally absorbed BA entered the circulation directly through the portal vein, whereas approximately 18.8% was transported into the blood via lymphatic transport. CBA-SMEDDS and BAPC-SMEDDS increased the lymphatic transport ratio of BA from 18.8% to 56.2% and 70.2%, respectively. Therefore, self-microemulsion not only significantly improves oral bioavailability of baicalein, but also increases the proportion lymphatically transported. This is beneficial to the direct interaction of baicalein with relevant immune cells in the lymphatic system and for proper display of its effects.

CONCLUSION

This study demonstrates the oral absorption and lymphatic transport characteristics of free baicalein and baicalein SMEDDS with different compositions. This is of great significance to studies on lymphatic targeted delivery of natural immunomodulatory compounds.

Self-Micro-Emulsifying Controlled Release of Eugenol Pellets: Preparation, In vitro/In vivo Investigation in Beagle Dogs

This report aimed to formulate self-micro-emulsifying (SMEDDS) controlled-release pellets delivery system to improve aqueous solubility and in vivo availability of eugenol, a main constituent of clove oil with multiple pharmacological activities. The optimal formulation of eugenol-SMEDDS was eugenol: ethyl oleate: cremophor EL: 1, 2-propylene glycol at the ratio of 5:5:12:8. The SMEDDS were observed under transmission electron microscopy (TEM), and the size distribution was measured with dynamic laser light scatting (DLS). The particle size, index of dispersity (PDI), and zeta potential (Z-potential) were 68.8 ± 0.1 nm, 0.285 ± 0.031, and - 11.62 ± 0.63 mV, respectively. Eugenol-SMEDDS exhibited substantial increased in vitro dissolution compared with the free eugenol. The eugenol-SMEDDS sustained-release pellets (eugenol-SMEDDS-SR pellets) comprising of eugenol-SMEDDS, hydroxypropyl methylcellulose (HPMC), microcrystalline cellulose (MCC), and ethyl cellulose (EC) coats were obtained via extrusion spheronization technique. Consequently, the obtained pellets observed under scanning electron microscopy (SEM) showed spherical shape with smooth surface, desirable drug loading capacity (7.18 ± 0.17%), greater stability, and controlled release. Meanwhile, the oral test showed that bioavailability of eugenol in pellets was highly improved 23.6-fold to the free eugenol. Overall, these results suggested that the improvement of the oral bioavailability of eugenol-SMEDDS-SR could be due to the successful incorporation of the drug into SMEDDS.

A Self-Nanoemulsifying Drug Delivery System for Enhancing the Oral Bioavailability of Candesartan Cilexetil: Ex Vivo and In Vivo Evaluation

The drug delivery of candesartan cilexetil encounters an obstacle of low absolute oral bioavailability which is attributed mainly to its low aqueous solubility and efflux by intestinal P-glycoprotein (P-gp) transporters. However, the extent of P-gp contribution in the reduced oral bioavailability of candesartan cilexetil is not clear. In this study, a previously developed candesartan cilexetil-loaded self-nanoemulsifying drug delivery system (SNEDDS) was evaluated for its ability to increase the drug oral bioavailability via the inhibition of intestinal P-gp transporters. Despite the developed SNEDDS showing P-gp inhibition activity, P-gp-mediated efflux was found to have a minor role in the reduced oral bioavailability of candesartan cilexetil. On the other hand, the high surfactant concentration used in SNEDDS formulation represents a major challenge toward their widespread application especially for chronically administered drugs. The designed acute and subacute toxicity studies revealed that the degree of intestinal mucosal damage decreases as the treatment period increases. The latter observation was attributed to the reversibility of surfactant-induced mucosal damage. Thus, the developed SNEDDS could be considered as a promising delivery system for enhancing the oral bioavailability of chronically administered drugs.

Self-emulsifying drug delivery systems: Impact of stability of hydrophobic ion pairs on drug release

The aim of this study was to evaluate the impact of stability of hydrophobic ion pairs (HIPs) in gastrointestinal (GI) fluids on their release from self-emulsifying drug delivery systems (SEDDS). HIPs of leuprolide (LEU), insulin (INS) and bovine serum albumin (BSA) were formed using various mono- and di-carboxylate surfactants i.e. sodium deoxycholate (SDC), sodium dodecanoate (SDD), sodium stearoyl glutamate (SSG) and pamoic acid di-sodium salt (PAM). HIPs were evaluated regarding precipitation efficiency, log Pn-butanol/water and dissociation behavior at various pH and ionic strength. Solubility studies of these HIPs were accomplished to identify suitable solvents for the formulation of SEDDS. Subsequently, HIPs were incorporated into SEDDS followed by characterization regarding zeta potential, stability and log DSEDDS/release medium. Independent from the type of (poly)peptides, PAM showed most efficient HIP properties among tested surfactants. The highest encapsulation efficiency with PAM was achieved at molar ratios of 1:1 for LEU, 1:3 for INS and 1:50 for BSA and log Pn-butanol/water of HIPs were increased at least 2.5 units. Dissociation studies showed that LEU-PAM, INS-PAM, BSA-PAM complexes were dissociated within 6 h up to 25%, 60% and 85% in GI fluids, respectively. These HIPs were successfully incorporated into SEDDS exhibiting negative zeta potential and high stability for 4 h. Log DSEDDS/release medium of LEU-PAM, INS-PAM, BSA-PAM complexes were 2.4 ± 0.7, 2.1 ± 0.62 and 1.6 ± 0.45, respectively. Findings of this study showed that stability of HIPs has great impact on log DSEDDS/release medium and consequently on their release from SEDDS.

Drug delivery systems for elemene, its main active ingredient β-elemene, and its derivatives in cancer therapy

β-elemene is a noncytotoxic Class II antitumor drug extracted from the traditional Chinese medicine Curcuma wenyujin Y. H. Chen et C. Ling. β-elemene exerts its effects by inhibiting cell proliferation, arresting the cell cycle, inducing cell apoptosis, exerting antiangiogenesis and antimetastasis effects, reversing multiple-drug resistance (MDR), and enhancing the immune system. Elemene injection and oral emulsion have been used to treat various tumors, including cancer of the lung, liver, brain, breast, ovary, gastric, prostate, and other tissues, for >20 years. The safety of both elemene injection and oral emulsion in the clinic has been discussed. Recently, the secondary development of β-elemene has attracted the attention of researchers and made great progress. On the one hand, studies have been carried out on liposome-based systems (including solid lipid nanoparticles [SLNs], nanostructured lipid carriers [NLCs], long-circulating liposomes, active targeting liposomes, and multidrug-loaded liposomes) and emulsion systems (including microemulsions, self-emulsion drug delivery systems [SEDDSs], and active targeting microemulsion) to solve the issues of poor solubility in water, low bioavailability, and severe phlebitis, as well as to improve antitumor efficacy. The pharmacokinetics of different drug delivery systems of β-elemene are also summarized. On the other hand, a number of highly active anticancer β-elemene derivatives have been obtained through modification of the structure of β-elemene. This review focuses on the two drug delivery systems and derivatives of β-elemene for cancer therapy.

Self-emulsifying drug–delivery systems modulate P-glycoprotein activity: role of excipients and formulation aspects

Self-emulsifying drug–delivery systems (SEDDS) have been widely employed to ameliorate the oral bioavailability of P-glycoprotein (P-gp) substrate drugs and to overcome multidrug resistance in cancer cells. However, the role of formulation aspects in the reduced P-gp activity is not fully understood. In this review, we first explore the role of various SEDDS excipients in the reduced P-gp activity with the main emphasis on the effective excipient concentration range for excipient-mediated modulation of P-gp activity and then we discuss the synergistic effect of various formulation aspects on the excipient-mediated modulation of P-gp activity. This review provides an approach to develop a rationally designed SEDDS to overcome P-gp-mediated drug efflux.