Effect of lipolysis on drug release from self-microemulsifying drug delivery systems (SMEDDS) with different core/shell drug location

Liver-Targeting Composite Nanocarrier Delivery System Based on Chitosan Nanoparticles and Phospholipid Complexes

Liver fibrosis is mainly caused by excessive accumulation of extracellular matrix and structural changes in the liver, ultimately leading to cirrhosis if left untreated. Reducing hyaluronan synthesis by inhibiting hyaluronic acid deposition or regulating the expression of hyaluronic synthase can ameliorate liver fibrosis symptoms. In this study, we aimed to improve the bioavailability and liver-targeting capacity of hydroxymethyl coumarin (4-MU) using a newly developed phospholipid complex chitosan nanoparticle (4-MU PC/CNP) optimized using the Box-Behnken design. The composite nanocarrier delivery system was formulated using solvent evaporation technology, and formulation and process parameters were evaluated. Furthermore, 4-MU PC/CNPs and their pharmacokinetics were characterized. The established 4-MU PC/CNPs had an average particle size of 153.07 ± 0.29 nm, a polydispersity index value of 0.383, and a positive zeta potential of ∼35.4 mV. Compared with 4-MUs, 4-MU PC/CNPs exhibited significantly improved water solubility, faster plasma clearance and tissue distribution, and better liver targeting. Pharmacokinetic analysis showed that the oral bioavailability of 4-MU in 4-MU PC/CNPs was significantly higher than that of simple 4-MU. In conclusion, 4-MU PC improved drug lipid (oil-water distribution coefficient of 1.31 ± 0.03) and water solubilities (2.05 times the drug substance). 4-MU PC/CNPs significantly improved 4-MU oral bioavailability, representing a promising approach for enhancing drug solubility. This study demonstrates that the targeting parameters of 4-MU PC/CNPs in the liver were all greater than 1, indicating that they specifically targeted the liver, thereby potentially alleviating liver fibrosis.

Development and pharmacokinetic evaluation of Neusilin® US2-based S-SNEDDS tablets for bosentan: Fasted and fed states bioavailability, IVIS® real-time biodistribution, and ex-vivo imaging

The study reported here aimed to develop and optimize the S-SNEDDS tablet of bosentan (BOS) and to investigate its pharmacokinetic and biodistribution properties. The BOS-loaded SNEDDS have been developed and characterized in a previous study. The BOS-loaded SNEDDS formulation was converted to S-SNEDDS using Neusilin® US2. The S-SNEDDS tablets were obtained using the direct compression technique, and in vitro dissolution, in vitro lipolysis, and ex-vivo permeability studies of the tablets were performed. The S-SNEDDS tablet and reference tablet (Tracleer®) were administered to male Wistar rats at 50 mg/kg dose by oral gavage in fasted and fed state conditions. The biodistribution of the S-SNEDDS tablet was investigated in Balb/c mice using fluorescent dye. The tablets were dispersed in distilled water before administration to animals. The relationship between in vitro dissolution data and in vivo plasma concentration was examined. The S-SNEDDS tablets showed 2.47, 7.49, 3.70, and 4.39 increases in the percentages of cumulative dissolution in FaSSIF, FeSSIF, FaSSIF-V2, and FeSSIF-V2, respectively, when compared to the reference, and increased the Cmax and AUC 2.65 and 1.28-fold and 4.73 and 2.37-fold in fasted and fed states, respectively, when compared to the reference. S-SNEDDS tablets also significantly reduced interindividual variability in both fasted and fed states (p < 0.05). The XenoLight™ DiR and VivoTag® 680XL labeled S-SNEDDS tablet formulation increased the real-time biodistribution in the body by factors of 2.4 and 3.4 and organ uptake and total emission increased by factors of 2.8 and 3.1, respectively. The IVIVR has been successfully established for S-SNEDDS tablets (R2 > 0.9). The present study confirms the potential of the S-SNEDDS tablet to enhance the in vitro and in vivo performance of BOS.

Preparation and evaluation of a lipid-based drug delivery system to ımprove valsartan oral bioavailability: pharmacokinetic and pharmacodynamic analysis

Antihypertensive treatment reduces the risk of cardiovascular complications in patients with high mortality with hypertension. Valsartan is highly selective antihypertensive that is rapidly absorbed after oral administration, but its oral bioavailability is only 25%. It is absorbed from the upper part of the gastrointestinal tract but is less soluble in this acidic environment. We aimed to develop a lipid-based formulation to produce a self-emulsifying drug delivery system (SEDDS) for valsartan. Solubility studies were performed to identify the components of the SEDDS that provided the best dissolution of valsartan. Ternary phase diagrams were drawn using the titration method with oil, surfactants and co-surfactants in which valsartan was highly soluble, and microemulsion formulations with the highest area were determined. Characterization and in vitro release studies were performed to optimize the formulation. In vitro release profiles of commercial and SEDDS formulations showed the F2 formulation release rate increased at pH 1.2 fasted state simulated gastric fluid. After oral administration, plasma drug concentrations in rats indicate that the F2 formulation provided a 4.2-fold greater AUC for valsartan than the commercial formulaiton, resulting in an 8.5-fold greater Cmax. These findings suggest the F2 formulation increases valsartan solubility, resulting in an improved oral pharmacokinetic profile. According to the pharmacodynamic study, the F2 formulation is more effective than the commercial formulation in restoring systolic and diastolic blood pressure within a few hours.

Self-Emulsifying Drug Delivery System Enhances Tissue Distribution of Cinnamaldehyde by Altering the Properties of the Mucus Layer

Oral delivery is considered the preferred route of administration due to its convenience and favorable compliance. However, this delivery often faces difficulties, such as poor solubility, limited absorption, and undesirable stability, especially for some volatile oils. The aim of this study was to develop self-emulsifying drug delivery systems (SEDDS) containing cinnamaldehyde (CA) to overcome these shortcomings. The CA-SEDDS were spherical and smooth with an average size of 14.96 ± 0.18 nm. Differential scanning calorimetry (DSC) and attenuated total reflection by Fourier transform infrared (ATR-FTIR) showed that CA has been successfully loaded into SEDDS. The accumulative release of CA-SEDDS (73.39%) was approximately 2.14-fold that of free CA when using simulated intestinal fluid as the release medium. A scanning electron microscope was used to observe the mucus network structure. Rheological tests found that CA-SEDDS can appropriately enhance the viscosity of the mucus system. We found from tissue distribution studies that CA was more widely distributed in various tissues in the CA-SEDDS group compared to the free CA group. The cinnamaldehyde and cinnamon acid also accumulated more in various tissues in the CA-SEDDS group than in the free CA group, especially in the kidney. These findings hinted that SEDDS exhibited lower irritation, good release, and penetration, which demonstrated great potential for utilizing CA. Our research supports the rational implications of SEDDS in delivering similar volatile substances by improving the solubility, mucus penetration, and stability, resulting in excellent clinical efficacy.

Supersaturation and Solubilization upon In Vitro Digestion of Fenofibrate Type I Lipid Formulations: Effect of Droplet Size, Surfactant Concentration and Lipid Type

Lipid-based formulations (LBF) enhance oral drug absorption by promoting drug solubilization and supersaturation. The aim of the study was to determine the effect of the lipid carrier type, drop size and surfactant concentration on the rate of fenofibrate release in a bicarbonate-based in vitro digestion model. The effect of the lipid carrier was studied by preparing type I LBF with drop size ≈ 2 µm, based on medium-chain triglycerides (MCT), sunflower oil (SFO), coconut oil (CNO) and cocoa butter (CB). The drop size and surfactant concentration effects were assessed by studying MCT and SFO-based formulations with a drop size between 400 nm and 14 µm and surfactant concentrations of 1 or 10%. A filtration through a 200 nm filter followed by HPLC analysis was used to determine the aqueous fenofibrate, whereas lipid digestion was followed by gas chromatography. Shorter-chain triglycerides were key in promoting a faster drug release. The fenofibrate release from long-chain triglyceride formulations (SFO, CNO and CB) was governed by solubilization and was enhanced at a smaller droplet size and higher surfactant concentration. In contrast, supersaturation was observed after the digestion of MCT emulsions. In this case, a smaller drop size and higher surfactant had negative effects: lower peak fenofibrate concentrations and a faster onset of precipitation were observed. The study provides new mechanistic insights on drug solubilization and supersaturation after LBF digestion, and may support the development of new in silico prediction models.

Maximizing the Oral Bioavailability of Poorly Water-Soluble Drugs Using Novel Oil-Like Materials in Lipid-Based Formulations

Lipid-based formulations, such as self-microemulsifying drug-delivery systems (SMEDDSs), are promising tools for the oral delivery of poorly water-soluble drugs. However, failure to maintain adequate aqueous solubility after coming into contact with gastrointestinal fluids is a major drawback. In this study, we examined the use of a novel cinnamic acid-derived oil-like material (CAOM) that binds drugs with a high affinity through π-π stacking and hydrophobic interactions, as an oil core in a SMEDDS for the oral delivery of fenofibrate in rats. The use of the CAOM in the SMEDDS resulted in an unprecedented enhancement in fenofibrate bioavailability, which exceeded the bioavailability values obtained using SMEDDSs based on corn oil, a conventional triglyceride oil, or Labrasol, an enhancer of intestinal permeation. Further characterization revealed that the CAOM SMEDDS does not alter the intestinal permeability and has no inhibitory activity on P-glycoprotein-mediated drug efflux. The results reported herein demonstrate the strong potential of CAOM formulations as new solubilizers for the efficient and safe oral delivery of drugs that have limited water solubility.

Enhanced Bioavailability of AC1497, a Novel Anticancer Drug Candidate, via a Self-Nanoemulsifying Drug Delivery System

AC1497 is an effective dual inhibitor of malate dehydrogenase 1 and 2 targeting cancer metabolism. However, its poor aqueous solubility results in low bioavailability, limiting its clinical development. This study was conducted to develop an effective self-nanoemulsifying drug delivery system (SNEDDS) of AC1497 to improve its oral absorption. Based on the solubility of AC1497 in various oils, surfactants, and cosurfactants, Capryol 90, Kolliphor RH40, and Transcutol HP were selected as the components of SNEDDS. After testing various weight ratios of Capryol 90 (20–30%), Kolliphor RH40 (35–70%), and Transcutol HP (10–35%), SNEDDS-F4 containing 20% Capryol 90, 45% Kolliphor RH40, and 35% Transcutol HP was identified as an optimal SNEDDS with a narrow size distribution (17.8 ± 0.36 nm) and high encapsulation efficiency (93.6 ± 2.28%). Drug release from SNEDDS-F4 was rapid, with approximately 80% of AC1497 release in 10 min while the dissolution of the drug powder was minimal (<2%). Furthermore, SNEDDS-F4 significantly improved the oral absorption of AC1497 in rats. The maximum plasma concentration and area under the plasma concentration–time curve of AC1497 were, respectively 6.82- and 3.14-fold higher for SNEDDS-F4 than for the drug powder. In conclusion, SNEDDS-F4 with Capryol 90, Kolliphor RH40, and Transcutol HP (20:45:35, w/w) effectively improves the solubility and oral absorption of AC1497.

Improved bioaccessibility of polymethoxyflavones loaded into high internal phase emulsions stabilized by biopolymeric complexes: A dynamic digestion study via TNO's gastrointestinal model

In this work, the bioaccessibility of polymethoxyflavones (PMFs) loaded in high internal phase emulsions (HIPE, ϕ_oil = 0.82) stabilized by whey protein isolate (WPI)-low methoxy pectin (LMP) complexes was evaluated using in vitro lipolysis and dynamic in vitro intestinal digestion studies. PMFs loaded HIPE was prepared by using aqueous dispersion of pre-formed biopolymeric complexes (WPI-LMP, 2:1 ratio) as the external phase and medium chain triglycerides oil (containing PMFs extracted from citrus peel) as the dispersed phase. The in vitro lipolysis study revealed that PMFs in HIPE became bioaccessible much higher than PMFs in medium chain triacylglycerols oil (MCT oil). In addition, by simulating the entire human gastrointestinal (GI) tract, the GI model TIM-1 demonstrated a 5- and 2-fold increase in the total bioaccessibility for two major PMFs encapsulated in HIPE, i.e. tangeretin (TAN) and nobiletin (NOB), respectively, as opposed to PMFs in MCT oil. Together these results from the digestion study showed that the incorporation of a high amount of PMFs into the viscoelastic matrix of HIPE could represent an innovative and effective way to design an oral delivery system. Such a system could be used to control and to improve the delivery of lipophilic bioactive compounds within the different compartments of the digestive tract, especially the human upper GI tract.

Formulation and In Vitro Evaluation of Self Microemulsifying Drug Delivery System Containing Atorvastatin Calcium

OBJECTIVE

The aim of this study was to develop a new dosage form as an alternative to the classical tablet forms of atorvastatin calcium (AtrCa). The formulation strategy was to prepare an optimum self micro emulsifying drug delivery system (SMEDDS) to overcome the problem of low solubility of the active substance.

METHODS

In this study, pseudo ternary phase diagrams were plotted determined by the solubility studies. According to the solubility studies; oleic acid was used as the oil phase, Tween 20 and Span 80 were used as the surfactants and ethanol was used as the co-surfactant. SMEDDS formulations were characterized according to pH, electrical conductivity, density, refractive index, viscosity, emulsification time, dispersibility, robustness of dilution stability, droplet size, polidispersity index, zeta potential, transmittance %, cloud point, content quantification %, chemical and physical stability. The lipolysis study was conducted under fed and fasted conditions. In vitro release studies and kinetic evaluation were carried out. Permeability studies were also examined with Caco-2 cell culture.

RESULTS

The droplet size of the optimized formulation did not change significantly in different medias over the test time period. Improved SMEDDS formulation will progress steadily without precipitating along the gastrointestinal tract. Lipolysis studies showed that the oil solution had been exposed to high amount of lipolysis compared to the SMEDDS formulation. The release rate of AtrCa from AtrCa- SMEDDS formulation (93.8%, at 15 minutes) was found as increased when the results were compared with commercial tablet formulation and pure drug. The permeability value of AtrCa from AtrCa- SMEDDS formulation was found higher than pure AtrCa and commercial tablet formulation, approximately 9.94 and 1.64 times, respectively.

CONCLUSION

Thus, lipid-based SMEDDS formulation is a potential formulation candidate for lymphatic route in terms of the increased solubility of AtrCa.

Preparation and in vitro performance evaluation of resveratrol for oral self-microemulsion

The purpose of this study was to improve the solubility of resveratrol (Res) by a self-microemulsifying drug-delivery system (SMEDDS). Through a solubility experiment, the pseudoternary phase diagram and ternary phase diagram were used to optimize the Res SMEDDS formula. The optimum formulation consisted of 5% IPM, 20% PEG400, and 65% Cremophor RH40. The water solubility, stability, in vitro release and antioxidant activity of the Res SMEDDS were characterized. The Res solubility in the SMEDDS was at least 1,000 times compared to that in water. The average droplet size of the microemulsion was 28.00±1.67 nm and uniform distribution. The Res SMEDDS should be stored at low temperature and in the dark to avoid light conditions. Res SMEDDS was able to improve the in vitro release rate of Res, and the in vitro release of Res from Res SMEDDS was significantly faster that of Res powder and unaffected by pH value of media. Antioxidant assays showed that antioxidant activities of Res in Res SMEDDS were unaffected compared to Res powder. Cytotoxicity study indicated that Res SMEDDS at the concentration of less than 100 μM was safe. These results demonstrated the potential use of Res SMEDDS for oral administration of Res.

Fourth-Generation Antibiotic Gatifloxacin Encapsulated by Microemulsions: Structural and Probing Dynamics

To overcome the increased disease rate, utilization of the versatile broad spectrum antibiotic drugs in controlled drug-delivery systems has been a challenging and complex consignment. However, with the development of microemulsion (μE)-based formulations, drugs can be effectively encapsulated and transferred to the target source. Herein, two biocompatible oil-in-water (o/w) μE formulations comprising clove oil/Tween 20/ethylene glycol/water (formulation A) and clove oil/Tween 20/1-butanol/water (formulation B) were developed for encapsulating the gatifloxacin (GTF), a fourth-generation antibiotic. The pseudoternary phase diagrams were mapped at a constant surfactant/co-surfactant (1:1) ratio to bound the existence of a monophasic isotropic region for as-formulated μEs. Multiple complementary characterization techniques, namely, conductivity (σ), viscosity (η), and optical microscopy analyses, were used to study the gradual changes that occurred in the microstructure of the as-formulated μEs, indicating the presence of a percolation transformation to a bicontinuous permeate flow. GTF showed good solubility, 3.2 wt % at pH 6.2 and 4.0 wt % at pH 6.8, in optimum μE of formulation A and formulation B, respectively. Each loaded μE formulation showed long-term stability over 8 months of storage. Moreover, no observable aggregation of GTF was found, as revealed by scanning transmission electron microscopy and peak-to-peak correlation of IR analysis, indicating the stability of GTF inside the formulation. The average particle size of each μE, measured by dynamic light scattering, increased upon loading GTF, intending the accretion of drug in the interfacial layers of microdomains. Likewise, fluorescence probing sense an interfacial hydrophobic environment to GTF molecules in any of the examined formulations, which may be of significant interest for understanding the kinetics of drug release.

In situ monitoring of the structural change of microemulsions in simulated gastrointestinal conditions by SAXS and FRET

Microemulsions are promising drug delivery systems for the oral administration of poorly water-soluble drugs. However, the evolution of microemulsions in the gastrointestinal tract is still poorly characterized, especially the structural change of microemulsions under the effect of lipase and mucus. To better understand the fate of microemulsions in the gastrointestinal tract, we applied small-angle X-ray scattering (SAXS) and fluorescence resonance energy transfer (FRET) to monitor the structural change of microemulsions under the effect of lipolysis and mucus. First, the effect of lipolysis on microemulsions was studied by SAXS, which found the generation of liquid crystalline phases. Meanwhile, FRET spectra indicated micelles with smaller particle sizes were generated during lipolysis, which could be affected by CaCl2, bile salts and lecithin. Then, the effect of mucus on the structural change of lipolysed microemulsions was studied. The results of SAXS and FRET indicated that the liquid crystalline phases disappeared, and more micelles were generated. In summary, we studied the structural change of microemulsions in simulated gastrointestinal conditions by SAXS and FRET, and successfully monitored the appearance and disappearance of the liquid crystalline phases and micelles.

Preparation and Optimization Lipid Nanocapsules to Enhance the Antitumor Efficacy of Cisplatin in Hepatocellular Carcinoma HepG2 Cells

This work aimed to develop and optimize several lipid nanocapsule formulations (LNCs) to encapsulate cisplatin (CDDP) for treatment of hepatocellular carcinoma. By comparing the effect of oil/surfactant ratio, lecithin content, and oil/surfactant type on LNC characteristics, two LNCs were selected as optimal formulations: HS15-LNC (Solutol HS 15/MCT/lecithin, 54.5:42.5:3%, w/w) and EL-LNC (Cremophor EL/MCT/lecithin, 54.5:42.5:3%, w/w). Both LNCs could effectively encapsulate CDDP with the encapsulation efficiency of 73.48 and 78.84%. In vitro release study showed that both LNCs could sustain the release CDDP. Moreover, cellular uptake study showed that C6-labeled LNCs could be effectively internalized by HepG2 cells. Cellular cytotoxicity study revealed that both LNCs showed negligible cellular toxicity when their concentrations were below 313 μg/mL. Importantly, CDDP-loaded LNCs exhibited much stronger cell killing potency than free CDDP, with the IC50 values decreased from 17.93 to 3.53 and 5.16 μM after 72-h incubation. In addition, flow cytometric analysis showed that the percentage of apoptotic cells was significantly increased after treatment with LNCs. Therefore, the prepared LNC formulations exhibited promising anti-hepatocarcinoma effect, which could be beneficial to hepatocellular carcinoma therapy.

Preparation and Pharmacokinetics Evaluation of Solid Self-Microemulsifying Drug Delivery System (S-SMEDDS) of Osthole

The study was performed aiming to enhance the solubility and oral bioavailability of poorly water-soluble drug osthole by formulating solid self-microemulsifying drug delivery system (S-SMEDDS) via spherical crystallization technique. Firstly, the liquid self-microemulsifying drug delivery system (L-SMEDDS) of osthole was formulated with castor oil, Cremophor RH40, and 1,2-propylene glycol after screening various lipids and emulsifiers. The type and amount of polymeric materials, good solvents, bridging agents, and poor solvents in S-SMEDDS formulations were further determined by single-factor study. The optimal formulation contained 1:2 of ethyl cellulose (EC) and Eudragit S100, which served as matrix forming and enteric coating polymers respectively. Anhydrous ethanol and dichloromethane with a ratio of 5:3 are required to perform as good solvent and bridging agent, respectively, with the addition of 0.08% SDS aqueous solution as poor solvent. The optimized osthole S-SMEDDS had a high yield (83.91 ± 3.31%) and encapsulation efficiency (78.39 ± 2.25%). Secondly, osthole L-SMEDDS was solidified to osthole S-SMEDDS with no significant changes in terms of morphology, particle size, and zeta potential. In vitro release study demonstrated a sustained release of the drug from osthole S-SMEDDS. Moreover, in vivo pharmacokinetic study showed that the T_max and mean residence time (MRT_(0-t)) of osthole were significantly prolonged and further confirmed that osthole S-SMEDDS exhibited sustained release effect in rabbits. Comparing with osthole aqueous suspension and L-SMEDDS, osthole S-SMEDDS increased bioavailability by 205 and 152%, respectively. The results suggested that S-SMEDDS was an effective oral solid dosage form, which can improve the solubility and oral bioavailability of poorly water-soluble drug osthole.

Biopharmaceutical insights of particulate emulsified systems - a prospective overview

During the twenty-first century, drug discovery is expanding rapidly and a large number of chemical moieties are recognized. Many of them are poorly soluble and hence related biopharmaceutical constraints are to be addressed systematically. Among novel approaches to resolving biopharmaceutical issues, micro- and nano-emulsified systems serve as the best strategy for delivering both hydrophobic and hydrophilic drugs owing to their greater solubilization and transportation capabilities. Of late, the unique physical and biopharmaceutical properties of these liquid isotropic homogenous systems have gained substantive research importance. In addition nano/micro lipid systems share structural and functional similarity with that of the physiological lipids which offer better tolerance ability in the body. In this context, this article provides information on the historical emergence of particulate emulsified systems, importance and rationale of selection of carriers. It also encompasses the physicochemical principles that are responsible for the elevation of therapeutic outcomes of delivery systems. Detailed and schematic absorption of these drug delivery systems is explained here. Gastro-intestinal biochemistry necessary in the understanding of digestion process, lipolytic products formed, micellar structures, enzymes, transporters, mechanism of cell uptake involved after subsequent oral absorption are also emphasized. In addition, this article also explains disposition and pharmacokinetic properties of emulsified systems with real-time therapeutic research outcomes. The influence of biochemical compositions and biopharmaceutical principles on absorption and disposition patterns of ME/NEs was described in the article for the interest of readers and young researchers.

Preparation of Essential Oil-Based Microemulsions for Improving the Solubility, pH Stability, Photostability, and Skin Permeation of Quercetin

Quercetin can bring many benefits to skin based on its various bioactivities. However, the therapeutic effect of quercetin is limited due to the poor water solubility, pH instability, light instability, and skin permeation. The aim of the present work was applying essential oil-based microemulsions to improve the solubility, pH stability, photostability, and skin permeation of quercetin for topical application. Peppermint oil (PO-ME), clove oil (CO-ME), and rosemary oil (RMO-ME) were selected as model essential oils. Microemulsions composed of Cremophor EL/1,2-propanediol/essential oils (47:23:30, w/w) were selected as model formulations, based on the pseudo-ternary phase diagram and the characterizations. In the solubility study, the solubility of quercetin was improved dozens of times by microemulsions. Quercetin was found instable under alkaline condition, with 50% degraded in the solution of pH 13. However, PO-ME, CO-ME, and RMO-ME could protect quercetin from the hydroxide ions, with 47, 9, and 12% of quercetin degraded. In the photostability study, the essential oil-based microemulsions showed the capability of protecting quercetin from degradation under UV radiation. Where more than 67% of quercetin was degraded in aqueous solution, while less than 7% of quercetin degraded in microemulsions. At last, the in vitro skin permeation study showed that the essential oil-based microemulsions could enhance the permeation capacity of quercetin by 2.5-3 times compared to the aqueous solution. Hence, the prepared essential oil microemulsions could improve the solubility, pH stability, photostability, and skin permeation of quercetin, which will be beneficial for its topical application.

Encapsulation of Antibiotic Levofloxacin in Biocompatible Microemulsion Formulation: Insights from Microstructure Analysis

Microemulsions (μEs) are unique systems that offer exciting perspectives in biophysical research for mimicing biomembranes at the molecular level. In the present study, biocompatible μE formulation of a new oil-in-water (o/w) system comprising clove oil/Tween 20/2-propanol/water was accomplished for encapsulating an antibiotic, levofloxacin (LVF). The pseudoternary phase diagram was delineated at a constant cosurfactant/surfactant (2:1) ratio to meet the economic feasibility. The gradual changes occurring in the microstructure of the as-formulated four-component μEs were explored via multiple complementary characterization techniques. The results of electrical conductivity (σ), viscosity (η), and optical microscopic measurements suggested the existence of a percolation transition to a bicontinuous structure in the microregions of the as-formulated μE. LVF displayed a high solubility (5.0 wt %) at the pH of 6.9 in an optimum μE formulation comprising 2-propanol (36.4%), Tween 20 (18.2%), clove oil (20.7%), and water (24.7%). The LVF-loaded μE composition showed long-term stability for over 6 months of storage. Fourier transform IR analysis showed that LVF was stable inside the μE formulation, indicating the absence of any possible aggregation of LVF. Dynamic light scattering revealed that the average particle size of drug-free μE (64.5 ± 3.4 nm) increases to 129.7 ± 5.8 nm upon loading of LVF, suggesting the accumulation of LVF in the interfacial layers of the micelles. Moreover, fluorescence measurements indicated that LVF might be localized in the interfacial film of μE system, which may result in a controlled release of drug.

Self-emulsifying drug delivery system developed by the HLB-RSM approach: Characterization by transmission electron microscopy and pharmacokinetic study

Recently, we developed a new approach to rationalize an optimized design for self-emulsifying drug delivery system (SEDDS) by introducing the HLB and the response surface as determinant factors in SEDDS development. The aim of this current paper is to assess the suitability of this HLB-RSM approach to enhance the oral bioavailability of BCS class II compounds using fenofibrate as drug model. Eight SEDDS formulations (I→VIII) were pre-selected regarding their self-emulsification capacity and their effect on increasing in vitro drug release. They were firstly evaluated for their thermodynamic stability and zeta potential. Unstable SEDDS were discarded meanwhile the structural morphology of the stable ones (I, VI and VIII) was characterized using transmission electron microscopy (TEM). A pharmacokinetic study was then undertaken on male BALB/cJRj mices. The in vivo results showed a significant increase of fenofibrate absorption for all the three stable SEDDS formulations compared to the commercialized form, (LIPANTHYL micronized(®) (p<0.05)). The highest enhancement was recorded for SEDDS I, where AUC and Cmax values respectively increased by 2 and 4.4 folds. This justifies the fact that HLB-RSM approach could be considered as a promising method for the development of efficient and highly stable SEDDS aiming to increase the poor bioavailability of BCS class II molecules.

Influence of microemulsion-mucin interaction on the fate of microemulsions diffusing through pig gastric mucin solutions

Mucus layer, a selective diffusion barrier, has an important effect on the fate of drug delivery systems in the gastrointestinal tract. To study the fate of microemulsions in the mucus layer, four microemulsion formulations with different particle sizes and lipid compositions were prepared. The microemulsion-mucin interaction was demonstrated by the fluorescence resonance energy transfer (FRET) method. Moreover, the microemulsions were observed aggregated into micron-sized emulsions by laser confocal microscopy. We concluded the microemulsion-mucin interaction not only led to microemulsions closely adhered to mucins but also destroyed the structure of microemulsions. At last, the diffusion of blank microemulsions and microemulsion-carried drugs (resveratrol and hymecromone) through mucin solutions was determined by the fluorescence recovery after photobleaching (FRAP) method and the Franz diffusion cell method. The results demonstrated the diffusion of microemulsions was significantly hindered by mucin solutions. The particle size of microemulsions had a negligible effect on the diffusion coefficients. However, the type of lipid played an important role, which could form hydrophobic interactions with mucins. Interestingly, microemulsion-carried drugs with different core/shell locations seemed to suffer different fates in the mucin solutions. The drug incorporated in the oil core of microemulsions, resveratrol, was transported through the mucus layer by the carriers, while the drug incorporated in the surfactant shell of microemulsions, hymecromone, was separated from the carriers and diffused toward the epithelium in the form of free molecules.

Recent advances of resveratrol in nanostructured based delivery systems and in the management of HIV/AIDS

Resveratrol, a natural polyphenolic compound present in trees, in peanuts, in grapevines and exhibited multiple pharmacological activities. Extensive research in last two decades suggested that resveratrol possesses anti-inflammatory, anti-cancer, anti-viral, anti-amyloid, anti-arthritic and antioxidant properties. Some clinical reports have proposed that resveratrol might be a potential candidate for the prevention and/or treatment of HIV/AIDS and synergistically enhances the anti-HIV-1 activity. Resveratrol is not toxic to cells, and by itself reduces viral replication by 20% to 30%. With almost 12% of the world population suffering from HIV/AIDS including its resurgence in the developed world, better management of this global threat is highly desired. Further, various studies demonstrated several issues associated with resveratrol which account for its poor systemic bioavailability (almost zero) due to rapid and extensive first pass metabolism and existence of enterohepatic recirculation. In order to improve bioavailability and cellular uptake of resveratrol, various strategies have been adopted to date which includes resveratrol prodrug and the development of nanostructured delivery systems. Besides, nanostructured delivery systems are also known to inhibit the P-glycoprotein (P-gp) efflux, reduced metabolism by gut cytochrome P-450 enzymes, and circumnavigate the hepatic first-pass effect, facilitating absorption of drugs via intestinal lymphatic pathways. This review paper provides an updated bird's-eye view account on the publications and patents study on the recent novel approaches to deliver resveratrol in order to enhance oral bioavailability, overcome first pass metabolism and trounce enterohepatic recirculation to make resveratrol a therapeutically potent drug. Providing a relatively pithy overview, this paper thus presents recent advances of resveratrol for the treatment and prevention of HIV/AIDS.