The emulsification and solubilisation properties of polyglycolysed oils in self-emulsifying formulations

Lipid Horizons: Recent Advances and Future Prospects in LBDDS for Oral Administration of Antihypertensive Agents

The lipid-based drug delivery system (LBDDS) is a well-established technique that is anticipated to bring about comprehensive transformations in the pharmaceutical field, impacting the management and administration of drugs, as well as treatment and diagnosis. Various LBDDSs verified to be an efficacious mechanism for monitoring hypertension systems are SEDDS (self-nano emulsifying drug delivery), nanoemulsion, microemulsions, vesicular systems (transferosomes and liposomes), and solid lipid nanoparticles. LBDDSs overcome the shortcomings that are associated with antihypertensive agents because around fifty percent of the antihypertensive agents experience a few drawbacks including short half-life because of hepatic first-pass metabolism, poor aqueous solubility, low permeation rate, and undesirable side effects. This review emphasizes antihypertensive agents that were encapsulated into the lipid carrier to improve their poor oral bioavailability. Incorporating cutting-edge technologies such as nanotechnology and targeted drug delivery, LBDDS holds promise in addressing the multifactorial nature of hypertension. By fine-tuning drug release profiles and enhancing drug uptake at specific sites, LBDDS can potentially target renin-angiotensin-aldosterone system components, sympathetic nervous system pathways, and endothelial dysfunction, all of which play crucial roles in hypertension pathophysiology. The future of hypertension management using LBDDS is promising, with ongoing reviews focusing on precision medicine approaches, improved biocompatibility, and reduced toxicity. As we delve deeper into understanding the intricate mechanisms underlying hypertension, LBDDS offers a pathway to develop next-generation antihypertensive therapies that are safer, more effective, and tailored to individual patient needs.

A multistage oral delivery system of PTX for improving oral bioavailability and enhancing anticancer efficacy

OBJECTIVE

Bromotetrandrine (W198) was reported as a P-glycoprotein (P-gp) inhibitor. We aimed to prepare oral W198 micelles following by paclitaxel (PTX) micelles (W198/PTX micelles) to improve the clinical application of PTX.

SIGNIFICANCE

The poor water solubility, intestinal permeability, and multidrug resistance (MDR) of PTX can be improved in the multistage oral delivery system.

METHODS

The novel W198/PTX oral micelles were developed by water-bath ultrasound method and were evaluated in vivo and in vitro in 4T1 orthotopic tumor-bearing mice model.

RESULTS

PTX micelles and W198 micelles were prepared to be round and uniform. W198 micelles pre-administrated group showed higher cellular uptake efficiency of PTX on Caco-2 cells and more prominent cytotoxicity compared with W198-untreated group on 4T1 cells. The oral bioavailability of W198/PTX micelles group was nearly 5.7-folds higher than the PTX micelles only group. In addition, W198/PTX micelles showed enhanced anticancer efficacy.

CONCLUSIONS

We established a multistage oral delivery system to improve oral bioavailability and anticancer efficacy of PTX.

Localized delivery of ibuprofen via a bilayer delivery system (BiLDS) for supraspinatus tendon healing in a rat model

The high prevalence of tendon retear following rotator cuff repair motivates the development of new therapeutics to promote improved tendon healing. Controlled delivery of non-steroidal anti-inflammatory drugs to the repair site via an implanted scaffold is a promising option for modulating inflammation in the healing environment. Furthermore, biodegradable nanofibrous delivery systems offer an optimized architecture and surface area for cellular attachment, proliferation, and infiltration while releasing soluble factors to promote tendon regeneration. To this end, we developed a bilayer delivery system (BiLDS) for localized and controlled release of ibuprofen (IBP) to temporally mitigate inflammation and enhance tendon remodeling following surgical repair by promoting organized tissue formation. In vitro evaluation confirmed the delayed and sustained release of IBP from Labrafil-modified poly(lactic-co-glycolic) acid microspheres within sintered poly(ε-caprolactone) electrospun scaffolds. Biocompatibility of the BiLDS was demonstrated with primary Achilles tendon cells in vitro. Implantation of the IBP-releasing BiLDS at the repair site in a rat rotator cuff injury and repair model led to decreased expression of proinflammatory cytokine, tumor necrotic factor-α, and increased anti-inflammatory cytokine, transforming growth factor-β1. The BiLDS remained intact for mechanical reinforcement and recovered the tendon structural properties by 8 weeks. These results suggest the therapeutic potential of a novel biocompatible nanofibrous BiLDS for localized and tailored delivery of IBP to mitigate tendon inflammation and improve repair outcomes. Future studies are required to define the mechanical implications of an optimized BiLDS in a rat model beyond 8 weeks or in a larger animal model.

In vitro evaluation of a self-emulsifying drug delivery system (SEDDS) for nasal administration of dimenhydrinate

The objective of the study was the development and in vitro characterization of a self-emulsifying drug delivery system (SEDDS) for the nasal application of dimenhydrinate. Final composition of SEDDS was established based on drug solubility and stability studies. Dimenhydrinate was loaded into the SEDDS pre-concentrates to 7.5% (m/v). The droplet size of the final SEDDS formulations was in a range between 60 and 220 nm. Permeability, as well as tissue toxicity, of the formulations was investigated using bovine nasal mucosa. Enhancement in permeation up to 2.8-fold compared to pure dimenhydrinate was confirmed. Furthermore, toxicity studies did not reveal any serious tissue damages related to the SEDDS. Additionally, irritation potential of SEDDS was evaluated in ciliary beat frequency measurements. Incorporation of dimenhydrinate into SEDDS might therefore be considered as a promising approach within the field of nasal delivery of antiemetics by utilizing permeation enhancement strategy.

Single-step and low-energy method to prepare solid lipid nanoparticles and nanostructured lipid carriers using biocompatible solvents

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLCs) are widely being explored for improving dermal/transdermal and oral delivery of drugs, neutraceuticals and cosmeceuticals. High-pressure homogenization (HPH) is the most commonly used preparation method for SLN/NLCs. SLN/NLCs preparation by the HPH requires high energy input and longer duration. Here, we describe a simple yet innovative low-energy method to prepare SLN/NLCs in a single-step using biocompatible solvents. We first show that biocompatible solvents such as Transcutol P, Soluphor P, N-methyl pyrrolidone, and glycofurol can solubilize glyceryl monostearate, glyceryl behenate, and glyceryl distearate to a variable degree. Our pre-formulation studies showed that only GMS could be transformed into SLN or NLCs despite high solubility of the lipids investigated indicating the importance of solvent-lipid interaction parameter in our preparation method. Finally, we show that SLN and NLCs of glyceryl monostearate with size < 150 nm and acceptable polydispersity index can be easily developed using Transcutol P as a biocompatible solvent and polyoxyl-40-stearate (MYS-40) as a stabilizer. As the Transcutol P has excellent acceptability for dermal/transdermal and oral route, there is no need to remove the residual Transcutol P (5% v/v) from the prepared glyceryl monostearate SLN/NLCs. Thus, our method offers a simple yet innovative way to prepare GMS SLN/NLCs suitable for dermal/transdermal and oral applications.

Biopharmaceutical Development of a Bifonazole Multiple Emulsion for Enhanced Epidermal Delivery

Efficient topical delivery of imidazolic antifungals faces the challenge of overcoming its limited water solubility and its required long-lasting duration of treatments. In this paper, a hydrophilic multiple emulsion (ME) of Bifonazole (BFZ) is shown to maximize its skin retention, minimize its skin permeation, and maintain an acceptable level of being harmless in vivo. The formulations were pharmaceutically characterized and application properties were assessed based on viscosity measurements. Non-Newtonian pseudoplastic shear thinning with apparent thixotropy was observed, facilitating the formulation retention over the skin. The in vitro release profile with vertical diffusion cells showed a predominant square-root release kinetic suggesting an infinite dose depletion from the formulation. Ex vivo human skin permeation and penetration was additionally evaluated. Respective skin permeation was lower than values obtained with a commercial O/W formulation. The combination of amphoteric and non-ionic surfactants increased the bifonazole epidermal accumulation by a factor of twenty. This fact makes the possibility of increasing its current 24 h administration frequency more likely. Eventual alterations of skin integrity caused by the formulations were examined with epidermal histological analysis and in vivo preclinical measurements of skin elasticity and water retrograde permeation. Histological analysis demonstrated that the multiple emulsions were harmless. Additionally, modifications of in vivo skin integrity descriptors were considered as negligible.

Armamentarium of nanoscaled lipid drug delivery systems customized for oral administration: In silico docking patronage, absorption phenomenon, preclinical status, clinical status and future prospects

Poor drug solubility and bioavailability remain a significant and frequently encountered concern for pharmaceutical scientists. Nanoscaled lipid drug delivery systems (NSLDDS) have exhibited great potentials in oral delivery of poorly water-soluble drugs, primarily for lipophilic drugs, with several successful clinical products. In the past few years, we have find out that optimized composition of drug in lipid, surfactant, or mixture of lipid and surfactant omits the solubility, permeability and bioavailability issues, which are potential limitations for oral absorption of poorly water-soluble drugs. Lipids not only vary in structures and physiochemical properties, but also in their digestibility and absorption pathway; therefore selection of lipid excipients and dosage form has a pronounced effect on biopharmaceutical aspects of drug absorption and distribution both in vitro and in vivo. Therefore, in current critical review, a comprehensive overview of the different lipid based nanostructured drug delivery systems intended for oral administration has been presented. In addition, implication of in silico docking in designing of NSLDDS as well as mechanism of absorption of different lipid based nanoformulations through intestinal absorption window has also been offered. Moreover, attention has also been paid to NSLDDS that are currently undergoing preclinical or clinical analysis.

Self-Emulsifying Formulation of Indomethacin with Improved Dissolution and Oral Absorption

Objectives

The objective of the present study was to enhance the solubility, dissolution and hence anti-inflammatory activity of poorly soluble drug indomethacin (IMN) by formulating into self emulsifying systems.

Materials and Methods

Self emulsifying formulations were prepared using capmul MCM as oil, tween 80 as surfactant, transcutol P as cosurfactant. Fourier transform infrared spectroscopy and differential scanning calorimetry studies were conducted to know the interaction between drug and excipients. Pseudo ternary phase diagrams were constructed using surfactant and cosurfactant in 1:1 to 1:4 and 2:1 to 4:1 to know the efficient self emulsification region. The formulations were evaluated for their particle size, zeta potential, refractive index, viscosity and cloud point. In vitro dissolution studies were conducted in one part of pH 7.2 phosphate buffer and four parts of water. The pharmacokinetic parameters were analysed by Win Nonlin software.

Results

The self emulsification was higher with the ratios 2:1, 3:1 and 1:2 of surfactant and co surfactant and the IMN formulations were prepared. The formulations were stable at different pH and dilutions. The globule size was in the range of 184.1 nm to 340.5 nm, as the ratio of oil, surfactant and cosurfactant mixture has varied effects on the size of globule. The negative charge on the globules of all formulations attributes their stability. The optimized formulation showed better release as compared to marketed product. The AUC of the optimised Self-Emulsifying Drug Delivery System was significantly higher than the marketed product.

Conclusion

Thus, from the present research, self emulsifying systems of IMN provide a useful alternative to enhance dissolution and hence anti inflammatory activity.

Calcium-alginate microparticles for sustained release of catechin prepared via an emulsion gelation technique

Catechin-loaded Ca-alginate beads and microparticles were prepared by an emulsion gelation method using sunflower oil for efficient sustained release of catechin. The emulsion was prepared by sequential mixing of alginate, oil, and oleic acid ester as an emulsifier. Encapsulation efficiency (EE) and inhibition of catechin release of the beads were significantly increased approximately to 453.83 and 148.71% by the emulsion gelation technique, respectively (p<0.05). For the microparticles, the highest inhibition of catechin release after 1 h of incubation (78.82%) was observed at the microparticles prepared by 5% (w/w) oil, 3% (w/w) alginate, 4% (w/v) CaCl₂, and 200 mg catechin with the most hydrophilic emulsifier, decaglycerol mono-ester. Moreover, the catechin release was sustained at acidic conditions and increased with increase in pH of release medium. These results suggest that catechin encapsulation within Ca-alginate particles by emulsion gelation method can be an effective delivery system for catechin.

Enhanced oral bioavailability of piperine by self-emulsifying drug delivery systems: in vitro, in vivo and in situ intestinal permeability studies

The main purpose of this work was to develop and evaluate a self-emulsifying drug delivery system (SEDDS) of piperine to enhance its solubility and bioavailability. The formulation was optimized by solubility test and ternary phase diagrams. Then physiochemical properties and in vitro release of SEDDS were characterized. In vivo pharmacokinetics study and in situ single-pass intestinal perfusion were performed to investigate the effects of SEDDS on the bioavailability and intestinal absorption of piperine. The optimized formulation was composed of ethyl oleate, Tween 80 and Transcutol P (3:5.5:1.5, w/w), with the level of the piperine reached 2.5% (w/w). The in vitro dissolution rates of piperine SEDDS were significantly higher than the self-prepared capsules. In vivo pharmacokinetic study showed Cmax1, Cmax2 and area under the curve of piperine after oral administration of SEDDS in rats were 3.8-, 7.2- and 5.2-fold higher than the self-prepared capsules, respectively, and the relative bioavailability of SEDDS was 625.74%. The in situ intestinal absorption study revealed that the effective permeability and the effective absorption rate values of piperine for SEDDS were significantly improved comparing to solutions (p < 0.01). So SEDDS formulation could improve the oral bioavailability and intestinal absorption of piperine effectively.

Development and Evaluation of Novel Self-Nanoemulsifying Drug Delivery Systems Based on a Homolipid from Capra hircus and Its Admixtures with Melon Oil for the Delivery of Indomethacin

In this study, goat fat (Capra hircus) and melon oil were extracted and used to formulate self-nanoemulsifying drug delivery systems (SNEDDS) based on either goat fat alone or its admixture with melon oil by employing escalating ratios of oil(s), surfactant blend (1 : 1 Tween 60 and Tween 80), and cosurfactant (Span 85), with or without carbosil, a glidant, for the delivery of indomethacin. The formulations were encapsulated in hard gelatin capsules and then assessed using isotropicity test, aqueous dilution stability and precipitation propensity, absolute drug content, emulsification time, in vitro drug release, and anti-inflammatory activity. The SNEDDS exhibited low precipitation propensity and excellent stability on copious dilution, as well as high drug release in vitro and in vivo. The inhibition produced by the SNEDDS was comparable to that of indomethacin injection (positive control) for much of the 5 h test period, indicating a high degree of bioavailability of the administered SNEDDS. The absolute drug contents and emulsification times fell within narrow limits. This study has shown that a 1 : 1 ratio of melon oil and goat fat could confer favourable properties with respect to drug release and anti-inflammatory activity on SNEDDS for the delivery of indomethacin, thus encouraging further development of the formulations.

Formulation and in vitro evaluation of self-emulsifying formulations of Cinnarizine

The main objectives of this study were to improve the aqueous solubility and to modify in vitro dissolution profile of hydrophobic drug using self-emulsifying drug delivery systems (SEDDS). SEDDS were formulated using Capmul PG-12, Cremophor RH 40 and Tween 20 at different weight ratios and incorporated with Cinnarizine. The drug incorporation into pre-concentrate and drug solubility in phosphate buffer (pH 7.2) were investigated. In addition, the mean droplet size and drug release profile of the SEDDS were also determined. The drug incorporation was over 120 mg per 0.5 g pre-concentrate regardless of the composition of the formulations. The solubility of Cinnarizine in phosphate buffer (pH 7.2) was at least 1500 μM in the SEDDS. Formulations with only 10% w/w Capmul PG-12 were less than 20 nm in mean diameter while those produced with at least 20% w/w Capmul PG-12 were more than 100 nm regardless of the ratios of Cremophor RH 40 to Tween 20. SEDDS showed a significant increase of the mean percentage drug release than pure drug (p < 0.0001). In general, the SEDDS with 30% w/w of Capmul PG-12 provided the greatest enhancement in drug solubility in phosphate buffer as well as rapid drug release despite forming larger droplets upon emulsification. The combination of Capmul PG-12, Tween 20 and Cremophor RH 40 can produce SEDDS which can be used as an alternative dosage form for poorly water soluble drug.

The developability classification system: application of biopharmaceutics concepts to formulation development

A revised classification system for oral drugs was developed using the biopharmaceutics classification system (BCS) as a starting point. The revised system is designed to have a greater focus on drug developability. Intestinal solubility, the compensatory nature of solubility and permeability in the small intestine and an estimate of the particle size needed to overcome dissolution rate limited absorption were all considered in the revised system. The system was then validated by comparison with literature on the in vivo performance of a number of test compounds. Observations on the test compounds were consistent with the revised classification, termed the developability classification system (DCS), showing it to be of greater value in predicting what factors are critical to in vivo performance than the widely used BCS.

Approaches for the development of solid and semi-solid lipid-based formulations

Interest in Lipid Based Drug Delivery (LBDD) has developed over the past decade fuelled by a better understanding of the multiple roles lipids may play in enhancing oral bioavailability. Moreover, the emergence of novel excipients with acceptable regulatory and safety profiles coupled with advances in formulation technologies have greatly improved the potential for successful lipid based formulations. With the growing interest in this field, there is an increasing need for guidelines in excipient selection and characterization; material handling, formulation design, and processing techniques to obtain effective and patient-compliant dosage forms. The aim of this review is to present the recent approaches in selecting the most appropriate lipid system(s); methods for characterization of their behavior in vitro and in vivo; and the current formulation and processing techniques to obtain various solid dosage forms.

Pluronic and tetronic copolymers with polyglycolyzed oils as self-emulsifying drug delivery systems

The potential of poly(ethylene oxide)-poly(propylene oxide) block copolymers Pluronic F127 (PF127) and Tetronic 304 (T304), 904 (T904) and 1307 (T1307) as components of solid self-(micro)emulsifying dosage forms, S(M)EDDS, was evaluated. The dependence of the self-associative properties of Tetronics on pH explained the low ability of the micelles to solubilize griseofulvin at acid pH (sevenfold increase) compared to at alkaline pH (12-fold). Blends of polyglycolyzed glycerides (Labrasol, Labrafac CC, and Labrafil M 1944CS) with each copolymer at two different weight ratios (80:20 and 60:40) were prepared, diluted in water, and characterized in terms of globule size, appearance and griseofulvin solubility. The blends with Labrasol led to microemulsions that are able to increase drug solubility up to 30-fold. SMEDD hard gelatine capsules filled with griseofulvin and Labrasol or Labrasol/copolymer 80:20 showed a remarkable increase in drug solubility and dissolution rate, particularly when T904, T1307 or PF127 was present in the blend. This effect was more remarkable when the volume of the dissolution medium was 200 ml (compared to 900 ml), which can be related to a higher stability of the microemulsion when there is a greater concentration of the copolymer and glyceride in the medium.

Development of a partially automated solubility screening (PASS) assay for early drug development

A medium-throughput, compound-saving, thermodynamic solubility assay for early drug development was developed. Solid compound suspended in heptane was used for simple, time-saving, and flexible compound distribution into 96-well plates, with minor risk to generate new physical forms during dispensing. Low volume, well-stirred incubation vessels were generated by using a combination of V-shaped wells, well caps, and vertically inserted stir bars. This allowed solubility determination up to 100 mg/mL in 40-80 microL volumes in aqueous and nonaqueous, low- and high-viscosity solvents. After removal of residual solid through syringe filters mounted on microtiter plates, the filtrate was quantified by ultra performance liquid chromatography (UPLC) using a 1.2 min gradient. Combined with a robotic liquid handling system, throughput was 45 samples per hour and >600 solubility measurements per week. Results from the partially automated solubility screening (PASS) assay correlated well with reported solubility values (r2 = 0.882). The PASS assay is useful for compound-saving, thermodynamic solubility measurement at the discovery-development interface where maximal solubility in many commonly used solvents needs to be determined. PASS results provide a basis for the identification of formulation strategies, the selection of appropriate excipients, and for the prediction of the potential in vivo behavior of compounds.

Characterization of prototype self-nanoemulsifying formulations of lipophilic compounds

This study describes the evaluation and characterization of a self-nanoemulsifying drug delivery system (SNEDDS) consisting of a nonionic surfactant (Cremophor RH40), a mixture of long chain mono-, di-, and triacylglycerides (Maisine 35-1 and Sesame oil) and ethanol. Compositions containing 10% (w/w) ethanol, 40%-60% (w/w) lipid content, and 30%-50% (w/w) Cremophor RH40 were identified as pharmaceutically relevant, robust, and self-nanoemulsifying when dispersed in aqueous media. The influence of adding three different lipophilic model drug compounds (danazol, halofantrine, and probucol) to the SNEDDS was evaluated. While danazol precipitated from the SNEDDS after dispersion in aqueous media, halofantrine and procubol remained solubilized. Halofantrine- and procubol-loaded SNEDDS were evaluated in both saline and in media simulating fasted and fed-state intestinal fluid (FaSSIF and FeSSIF) using dynamic light scattering and small-angle X-ray scattering (SAXS) techniques. Stable nanoemulsions with droplet sizes in the range of 20-50 nm were formed in all media and with and without drugs. The mean size of the droplets was neither affected significantly by being dispersed into the media simulating gastro intestinal fluid, nor by addition of the drug.

Increasing the Proportional Content of Surfactant (Cremophor EL) Relative to Lipid in Self-emulsifying Lipid-based Formulations of Danazol Reduces Oral Bioavailability in Beagle Dogs

PURPOSE

To investigate the impact of a change in the proportions of lipid, surfactant and co-solvent on the solubilisation capacity of self-emulsifying formulations of danazol during in vitro dispersion and digestion studies and correlation with in vivo bioavailability in beagle dogs.

METHODS

Formulations from within the phase diagram of the pseudo-ternary system composed of soybean oil:maisine 35-1 (1:1 w/w), Cremophor EL and ethanol were assessed in vitro on dispersion and digestion. The relative bioavailability of danazol after administration of a series of these formulations was also determined.

RESULTS

All formulations formed microemulsions in the presence of water and no drug precipitation was observed on dispersion. In contrast, drug solubilisation was markedly affected by lipase-mediated digestion and a reduction in lipid (and increase in surfactant) content resulted in increased drug precipitation. Consistent with these data, the bioavailability of danazol decreased significantly when the lipid content in the formulations was reduced.

CONCLUSION

A rank-order correlation was observed between the patterns of solubilisation obtained during in vitro digestion and the in vivo performance of self-emulsifying formulations of danazol. In general a decrease in the lipid content and an increase in the proportions of surfactant and co-solvent resulted in reduced danazol bioavailability.

The novel formulation design of self-emulsifying drug delivery systems (SEDDS) type O/W microemulsion I: enhancing effects on oral bioavailability of poorly water soluble compounds in rats and beagle dogs

We examined the design of the versatile novel self-emulsifying drug delivery systems (SEDDS) type O/W microemulsion formulation which enhances the oral bioavailability by raising the solubility of poorly water soluble compounds. Namely, seven kinds of poorly water soluble compounds such as disopyramide, ibuprofen, ketoprofen, tolbutamide, and other new compounds, as the model compounds were used to compare the plasma concentration profile of the compound following single oral administration of each compound to rats and beagle dogs as a solution, an oily solution, a suspension (or a powder), an O/W microemulsion, and a SEDDS type O/W microemulsion. And the enhancing effect of the SEDDS type O/W microemulsion on the gastrointestinal absorption of these compounds was evaluated. In the components of the SEDDS type O/W microemulsion, medium chain fatty acid triglyceride (MCT), diglyceryl monooleate (DGMO-C), polyoxyethylene hydrogenated castor oil 40 (HCO-40), and ethanol were used as an oil, a lipophilic surfactant, a hydrophilic surfactant, and a solubilizer, at the mixture ratio of 25/5/45/25 (w/w%), respectively. Thereby, to six kinds of the model compounds except disopyramide, the solubility was from 340 to 98,000 times that in water, and the AUCs in plasma concentration of the compound were equivalent to that of solution or O/W microemulsion administration, or was increased by 1.5 to 78 times that of suspension administration. Accordingly, this novel SEDDS type O/W microemulsion is the versatile, useful formulation which enhances the oral bioavailability by raising the solubility of poorly water soluble compounds.

The novel formulation design of self-emulsifying drug delivery systems (SEDDS) type O/W microemulsion III: the permeation mechanism of a poorly water soluble drug entrapped O/W microemulsion in rat isolated intestinal membrane by the Ussing chamber method

We used ibuprofen as a poorly water soluble model drug, to examine the influence of bile salts and mucin layers on the permeability of that entrapped in an O/W microemulsion, in a rat isolated intestinal membrane by the Ussing chamber method. Under the presence of 3 kinds of the primary bile salts such a sodium taurocholate, etc., or a secondary bile salt such a sodium taurochenodeoxycholate at 0.01 mmol/L concentration, a significant difference was not demonstrated in the permeation clearance of the ibuprofen entrapped O/W microemulsion, as compared with the case without the bile salts. Thus, the bile salts did not have a remarkable influence on the permeability of the drug entrapped in the O/W microemulsion, and it was verified that this O/W microemulsion was hardly influenced by the flow of the bile secretion. On the other hand, when N-acetyl-L-cysteine (NAC) with the removal ability of a mucin layer was combined with the ibuprofen entrapped O/W microemulsion at the concentration of 3 and 10 mmol/L, it was shown that the permeation clearance of free ibuprofen did not decrease, but that of ibuprofen entrapped in the O/W microemulsion decreased with the increase of the NAC concentration. Therefore, it is confirmed that the mucin layer participates in the permeability of the drug entrapped in the O/W microemulsion. From these results, the mechanism in which the drug entrapped in the O/W microemulsion is released in a mucin layer, without passing through the route of the mixed micelle formation by bile, thereafter the drug permeates an intestinal membrane, is supposed.

The novel formulation design of O/W microemulsion for improving the gastrointestinal absorption of poorly water soluble compounds

The design of the novel O/W microemulsion formulation, which enhances the oral bioavailability by raising the solubility of poorly water soluble compounds was examined. Using medium chain fatty acid triglyceride (MCT), diglyceryl monooleate (DGMO-C), polyoxyethylene hydrogenated castor oil 40 (HCO-40), ethanol and PBS (pH 6.8) as an oil phase, a lipophilic surfactant, a hydrophilic surfactant, a solubilizer and an aqueous phase, at the mixture ratio of 5%/1%/9%/5%/80% (w/w), respectively, the O/W microemulsion with an average particle diameter of 20 nm or less was prepared. Moreover, for nine kinds of poorly water soluble compounds, such as Ibuprofen, Ketoprofen, Tamoxifen, Testosterone, Tolbutamide and other new compounds, the solubility to water was increased from 60 to 20,000 times by this O/W microemulsion formulation. The AUCs in plasma concentration of Ibuprofen and a new compound, ER-1039, following single oral administration of these compounds as the O/W microemulsion to fasted rats were equivalent to that of solution administration or increased by nine and two times that of suspension administration, respectively. Accordingly, this novel O/W microemulsion is a useful formulation, which enhances the oral bioavailability by raising the solubility of poorly water soluble compounds.

The development and characterisation of triglyceride-based ‘spontaneous’ multiple emulsions

The formation of multiple emulsion droplets from two oil systems (Labrafil M 1944 CS and Labrafac Lipophile WL 1349) via a one-step process involving minimal agitation in aqueous media has been investigated in terms of the multiple character of the droplets, the particle size distribution, the stability and the lipolysis profile in the presence of pancreatic lipase. It was noted that multiple emulsion droplets were formed from both oils in the presence and absence of Tween 80, with the stability and particle size of the droplets being dependent on the composition and choice of media. It was noted that optimum stability of up to several days was obtained using 10% Tween 80 for both oils, with two stages of the breakdown process being apparent, the relative propensities of which being dependent on the oil used. The particle size distribution in distilled water indicated the presence of two distinct size populations corresponding to multiple and single droplets. It was noted that droplet breakdown was greatly accelerated in simulated intestinal fluid and in high pH media, with evidence for liquid crystal structure formation apparent. Lipolysis studies indicated that pegylation and the presence of surfactant slowed the degradation process. The study has indicated that 'spontaneous' multiple emulsion formation is indeed possible, with a reasonable if not necessarily optimal stability profile being observed for these systems.

The Novel Formulation Design of Self-emulsifying Drug Delivery Systems (SEDDS) Type O/W Microemulsion II: Stable Gastrointestinal Absorption of a Poorly Water Soluble New Compound, ER-1258 in Bile-fistula Rats

The stabilization effect of the novel self-emulsifying drug delivery systems (SEDDS) type O/W microemulsion on the gastrointestinal absorption of a poorly water soluble new compound, ER-1258 was examined by bile-fistula model rats. In the components of this formulation, medium chain fatty acid triglyceride (MCT), diglyceryl monooleate (DGMO-C), polyoxyethylene hydrogenated castor oil 40 (HCO-40) and ethanol were used as an oil, a lipophilic surfactant, a hydrophilic surfactant and a solubilizer at the mixture ratio of 25/5/45/25 w/w%, respectively. The ratios of AUC in the non-treated rats to that in the bile-fistula rats were 5.1, 12.1 and 3.0 for the suspension, the oily solution and the SEDDS type O/W microemulsion, respectively. The risk from which the difference between individuals of the compound absorption amounts resulting from the flow of the bile secretion serves as the maximum was high in order of oily solution>suspension>SEDDS type O/W microemulsion. Therefore, it was verified that the SEDDS type O/W microemulsion was able to reduce this risk, compared with the other formulations. When short chain fatty acid triglyceride (Triacetin) was used as an oil, the similar effect was demonstrated in the formulation composed of sorbitan sesquioleate (SO-15) as a lipophilic surfactant and polyoxyethylene hydrogenated castor oil 60 (HCO-60) or polyoxyethylene 20 sorbitan monooleate (TO-10M) as a hydrophilic surfactant.