The characterisation, pharmacokinetic and tissue distribution studies of TPGS modified myricetrin mixed micelles in rats

Development and optimization of sustained release triptolide microspheres

Rheumatoid arthritis is considered a chronic systemic autoimmune disorder that may cause joint destruction. Triptolide, an active component isolated from Tripterygium wilfordii Hook.f., is considered to have promising potential for clinical use in treating rheumatoid arthritis. However, its clinical application has been limited by the narrow therapeutic window, side effects associated with plasma drug fluctuations, low oral bioavailability, and poor patient compliance with the long and frequent dosing regimen. An extended drug release preparation may address these limitations. The aim of this work was therefore to develop, formulate and optimize sustained release triptolide microspheres with poly (lactide-co-glycolide) (PLGA). Triptolide-loaded microspheres were prepared using PLGA as the matrix polymer, dichloromethane as the oil phase, and polyvinyl alcohol (PVA) as the matrix forming emulsifier. An oil-in-water (O/W) emulsion solvent evaporation technique was utilized to prepare the microspheres. Surface response methodology (RSM) coupled with central composite design (CCD) was used to optimize the formulation and a total of twenty formulations were prepared. PVA concentration (X1), PLGA concentration (X2), and theoretical drug content (X3) were selected as independent variables; and drug content (Y1), encapsulation efficiency (Y2), mean diameter (Y3) and the initial release during the first day (Y4) were taken as the response variables. The optimized formulation showed mean diameter of 42.36 μm, drug content of 7.96%, encapsulation efficiency of 80.16% and an initial release of 14.48%. The prepared microspheres exhibited a sustained release profile of triptolide in vitro over 4 weeks, which was wellfitted with a Korsmeyer-Peppas equation. However, the initial drug release (~14%) of triptolide-loaded microspheres was very high and should be specifically investigated in future studies. The results indicate that long-term sustained release microspheres of triptolide can be considered a strategy to overcome the low bioavailability and poor patient compliance with conventional triptolide tablets. The issue of initial burst release and in vivo evaluations should be specifically investigated in the future.

Preparation, Physical Characterization, Pharmacokinetics and Anti-Hyperglycemic Activity of Esculetin-Loaded Mixed Micelles

Despite its low water solubility, esculetin (EC) have been described to demonstrate various health benefits. Thus, we sought to develop esculetin-loaded mixed micelles (EC-M) delivery system to purposively improve biological availability and anti-hyperglycemia activity of EC. Thin-film hydration method was employed to fabricate EC-M, amid characterization with transmission electron microscopic analysis (TEM), coupled with physical properties such as particle size (PS), poly-dispersity index (PDI), zeta-potential (ZP) and stability testing. We analyzed in-vitro release and studied EC-M pharmacokinetics in rats. The hyperglycemic mice model was established with streptozotocin (STZ) to evaluate anti-hyperglycemic activity of EC-M. The PS, PDI and ZP of EC-M were 47.97 ± 0.41 nm, 0.189 ± 0.005 and -25.55 ± 0.28 mV, respectively. The release rate of EC-M increased comparable to free EC in the three media. The oral biological availability and half-life of EC-M increased respectively by 3.06 and 1.45 folds compared to free EC. Besides, we observed 46.21% decrease in blood glucose of mice in EC-M group comparable to the model control, wherein, the anti-hyperglycemic effect of EC-M was better compared to free EC. Conclusively, EC-M may ideally serve as a novel approach to enhance biological availability and increased anti-hyperglycemic activity of EC.

Hyperoside-loaded TPGs/mPEG-PDLLA self-assembled polymeric micelles: preparation, characterization and in vitro/in vivo evaluation

Hyperoside (Hyp) self-assembled polymeric micelles (Hyp-PMs) were purposely developed to enhance aqueous solubility, in vivo availability and anti-oxidative effect of Hyp. In preparing Hyp-PMs, we employed the thin film dispersion method with the micelles consisting of TPGs and mPEG2000-PDLLA3000. The particle size, polydispersity index and zeta potential of Hyp-PMs were 67.42 ± 1.44 nm, 0.229 ± 0.015 and -18.67 ± 0.576 mV, respectively, coupled with high encapsulation efficiency (EE)of 90.63 ± 1.45% and drug loading (DL) of 6.97 ± 1.56%. Furthermore, the value of critical micelle concentration (CMC) was quite low, which indicated good stability and improved self-assembly ability of Hyp-PMs. Also, trend of in vitro Hyp release from Hyp-PMs demonstrated enhanced solubility of Hyp. Similarly, in comparison with free Hyp, oral bioavailability of Hyp-PMs was improved (about 8 folds) whilst half-life of Hyp-PMs was extended (about 3 folds). In vitro anti-oxidative effect showed obvious strong scavenging DPPH capability of Hyp-PMs, which may be attributed to its smaller size and better solubility. Altogether, Hyp-PMs may serve as a possible strategy to potentially enhance aqueous solubility, bioavailability and anti-oxidative effect of Hyp, which may play a key role in Hyp application in the pharmaceutical industries.

Enhanced oral bioavailability and anti-hyperuricemic activity of liquiritin via a self-nanoemulsifying drug delivery system

BACKGROUND

This study focused on the development of a self-nanoemulsifying drug delivery system (SNEDDS) to improve, potentially, the solubility and oral bioavailability of liquiritin (LQ).

METHODS

The solubility of LQ in different types of excipient, namely oils (OLs), emulsifiers (EMs), and co-emulsifiers (CO-EMs), was evaluated, and a pseudo-ternary phase diagram (PTPD) and the formulation optimization were established. The prepared self-nanoemulsifying drug delivery system of liquiritin (LQ-SNEDDS) was assessed using droplet size (DS), zeta potential (ZP), polydispersity index (PDI), droplet morphology, drug release in vitro, and oral bioavailability.

RESULTS

After the dilution of the LQ-SNEDDS, a transparent nanoemulsion was obtained with an acceptable DS (24.70 ± 0.73 nm), ZP (-18.69 ± 1.44 mV), and PDI (0.122 ± 0.006). The LQ-SNEDDS that was developed had a better release rate in vitro than the free LQ suspension. Pharmacokinetic evaluation showed that the relative oral bioavailability of LQ-SNEDDS was increased by 5.53 times, and LQ-SNEDDS exhibited a delayed half life and longer retention time in comparison with those of free LQ. Similarly, LQ-SNEDDS had a better urate lowering effect and provided better organ protection than free LQ at the same dose (P < 0.05).

CONCLUSIONS

The incorporation of LQ into SNEDDS could serve as a promising approach to improve the solubility, oral bioavailability, and anti-hyperuricemic effect of LQ. © 2021 Society of Chemical Industry.

Myricetin loaded nano-micelles delivery system reduces bone loss induced by ovariectomy in rats through inhibition of osteoclast formation

In recent years, much attention has been paid to the therapeutic effects of phytochemicals on osteoporosis. Other studies have shown that myricetin (MY) could promote osteogenic activity and inhibit osteoclastic effect, albeit little is known about effect of MY micellar system on osteoporosis. Therefore, we sought to discuss the therapeutic effect and mechanism of MY-loaded bone-targeting micelles on osteoporosis induced by ovariectomy (OVA) in rats. The AL-P(LLA-CL)-PEG-P(LLA-CL)-MY micelles were prepared via ethanol injection method, while in vitro release study, bone targeting, pharmacokinetic studies, and the effect on proliferation of osteoblasts were investigated. Further, the therapeutic effect on osteoporosis was studied through ovariectomized rats. Compared with free MY, oral bioavailability of AL-P(LLA-CL)-PEG-P(LLA-CL)-MY micelles in rats was increased by 3.54 times. The AL-P(LLA-CL)-PEG-P(LLA-CL)-MY micelles exhibited bone targeting potential, and could significantly increase the activity of alkaline phosphatase and promote the proliferation of osteoblasts. Importantly, AL-P(LLA-CL)-PEG-P(LLA-CL)-MY micelles mainly regulated bone metabolism by inhibiting bone resorption, thereby improving the symptoms of osteoporosis in OVA rats. The AL-P(LLA-CL)-PEG-P(LLA-CL)-MY micelles substantially enhanced the oral bioavailability of MY and demonstrated good bone targeting capability, thereby suggesting its prospect as carrier for osteoporotic improvement in OVA rats.

Preparation, characterization, pharmacokinetics, and antirenal injury activity studies of Licochalcone A-loaded liposomes

A liposome of Licochalcone A (LCA-Liposomes) was purposively prepared to ameliorate the low in vivo availability and efficacy of LCA. Physical characterization of LCA-Liposomes was carried out mainly by determining particle size, morphology, zeta potential (Z-potential), and efficiency of LCA encapsulation (EE) via appropriate techniques. Also, the rate of LCA release in vitro and distribution in vivo (plasma and tissues) was evaluated. Evaluation of the antirenal activity of LCA-liposomes was carried out by establishing chronic renal failure (CRF) model in mice through intragastric administration of adenine (200 mg/kg) and subsequent determination of biochemical parameters and examination of tissue sections. Respectively, the mean size of liposomal particles, Z-potential and EE of LCA-Liposomes were 71.78 ± 0.99 nm, -38.49 ± 0.06 mV, and 97.67 ± 1.72%. Pharmacokinetic and tissue distribution studies showed that LCA-Liposomes could improve the availability of LCA in the blood and tissues, whereas during pharmacodynamics studies, the liposome effectively improved the therapeutic effect of LCA on CRF mice by potentially protecting the renal tissues while exhibiting antioxidant activity. In conclusion, LCA-Liposomes could effectively improve the bioavailability of LCA and provide platform for the development of LCA-related functional products. PRACTICAL APPLICATIONS: As a traditional Chinese medicine, licorice is widely used in food and pharmaceutical industries. LCA is a small molecule flavonoid extracted from the root of licorice. In this study, LCA was loaded on liposome carriers, which significantly improved the water solubility and oral bioavailability, and proved that LCA-Liposomes have certain therapeutic effects on chronic renal failure, thereby providing a basis for the development of LCA into drugs or functional food in the future.

Improving oral bioavailability of medicinal herbal compounds through lipid-based formulations - A Scoping Review

BACKGROUND

Although numerous medicinal herbal compounds demonstrate promising therapeutic potential, their clinical application is often limited by their poor oral bioavailability. To circumvent this barrier, various lipid-based herbal formulations have been developed and trialled with promising experimental results.

PURPOSE

This scoping review aims to describe the effect of lipid-based formulations on the oral bioavailability of herbal compounds.

METHODS

A systematic search was conducted across three electronic databases (Medline, Embase and Cochrane Library) between January 2010 and January 2021 to identify relevant studies. The articles were rigorously screened for eligibility. Data from eligible studies were then extracted and collated for synthesis and descriptive analysis using Covidence.

RESULTS

A total of 109 studies were included in the present review: 105 animal studies and four clinical trials. Among the formulations investigated, 50% were emulsions, 34% lipid particulate systems, 12% vesicular systems, and 4% were other types of lipid-based formulations. Within the emulsion system classification, self-emulsifying drug delivery systems were observed to produce the best improvements in oral bioavailability, followed by mixed micellar formulations. The introduction of composite lipid-based formulations and the use of uncommon surfactants such as sodium oleate in emulsion preparation was shown to consistently enhance the bioavailability of herbal compounds with poor oral absorption. Interestingly, the lipid-based formulations of magnesium lithospermate B and Pulsatilla chinensis produced an absolute bioavailability greater than 100% indicating the possibility of prolonged systemic circulation. With respect to chemical conjugation, D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) was the most frequently used and significantly improved the bioavailability of its phytoconstituents.

CONCLUSION

Our findings suggest that there is no distinct lipid-based formulation superior to the other. Bioavailability improvements were largely dependent on the nature of the phytoconstituents. This scoping review, however, provided a detailed summary of the most up-to-date evidence on phytoconstituents formulated into lipid preparations and their oral bioavailability. We conclude that a systematic review and meta-analysis between bioavailability improvements of individual phytoconstituents (such as kaempferol, morin and myricetin) in various lipid-based formulations will provide a more detailed association. Such a review will be highly beneficial for both researchers and herbal manufacturers.

Improved oral bioavailability, cellular uptake, and cytotoxic activity of zingerone via nano-micelles drug delivery system

Herein, a nano-micelle drug delivery system was developed to orally improved zingerone's bioavailability and its antitumor effect. Indeed, zingerone-loaded d-α-tocopheryl polyethylene glycol succinate micelles (ZTMs) were effectively prepared, characterised and assessed. The ZTMs had diameter, polydispersity index, and zeta potential of 50.62 ± 0.25 nm, 0.168 ± 0.006, and -28.07 ± 0.33 mV, respectively, coupled with a high entrapment efficiency (m/m, %) were 94.71 ± 2.02. The release rate of ZTMs in three media was significantly greater than that of free zingerone. Intriguingly, results obtained from pharmacokinetic studies showed that the oral bioavailability of the ZTMs was enhanced by 5.10 times in comparison with the free zingerone. Further, the half inhibitory concentration (IC50) of ZTMs and free zingerone was 7.56 μg/ml and 14.30 μg/ml, respectively, on HepG2 cells. Hence, ZTMs may be used as a potential approach to enrich the solubility, bioavailability, and concomitant anti-proliferative effect of zingerone in vitro.

Enhancement of bioavailability and bioactivity of diet-derived flavonoids by application of nanotechnology: a review

Flavonoids, which are a class of polyphenols widely existing in food and medicine, have enormous pharmacological effects. The functional properties of flavonoids are mainly distributed to their anti-oxidative, anticancer, and anti-inflammatoryeffects, etc. However, flavonoids' low bioavailability limits their clinical application, which is closely related to their intestinal absorption and metabolism. In addition, because of the short residence time of oral bioactive molecules in the stomach, low permeability and low solubility in the gastrointestinal tract, flavonoids are easy to be decomposed by the external environment and gastrointestinal tract after digestion. To tackle these obstacles, technological approaches like microencapsulation have been developed and applied for the formulation of flavonoid-enriched food products. In the light of these scientific advances, the objective of this review is to establish the structural requirements of flavonoids for appreciable anticancer, anti-inflammatory, and antioxidant effects, and elucidate a comprehensive mechanism that can explain their activity. Furthermore, the novelty in application of nanotechnology for the safe delivery of flavonoids in food matrices is discussed. After a literature on the flavonoids and their health attributes, the encapsulation methods and the coating materials are presented.

Mixed micelles for enhanced oral bioavailability and hypolipidemic effect of liquiritin: preparation, in vitro and in vivo evaluation

OBJECTIVES

Liquiritin, as one of the main flavonoids in Glycyrrhiza, exhibits extensive pharmacological effects, such as the anti-oxidant, anti-inflammatory, anti-tumor and so on. Herein, the aqueous solubility and oral bioavailability of liquiritin was purposely enhanced via the preparation of the mixed micelles.

METHODS

The liquiritin-loaded micelles (LLM) were fabricated via thin-film dispersion method. The optimal LLM formulation was evaluated through physical properties including particle size (PS), encapsulation efficiency (EE) and drug loading (DL). In vitro accumulate release as well as in vivo pharmacokinetics were also evaluated. Moreover, the hypolipidemic activity of LLM was observed in the hyperlipidemia mice model.

RESULTS

The LLM exhibited a homogenous spherical shape with small mean PS, good stability and high encapsulation efficiency. The accumulate release rates in vitro of the LLM were obviously higher than free liquiritin. The oral bioavailability of the formulation was heightened by 3.98 times in comparison with the free liquiritin. More importantly, LLM increased the hypolipidemic and effect of alleviating lipid metabolism disorder in hepatocytes of liquiritin in hyperlipidemia mice model.

CONCLUSIONS

Collectively, the improved solubility of liquiritin in water coupled with its enhanced oral bioavailability and concomitant hypolipidemic activity could be attributed to the incorporation of the drug into the mixed micelles.

Improved oral bioavailability and anti-chronic renal failure activity of chrysophanol via mixed polymeric micelles

AIMS

This study was designed to prepare chrysophanol-loaded micelles (CLM) to improve the oral bioavailability, targetability and anti-chronic renal failure (CRF) activity of chrysophanol (CH).

METHODS

The preparation of CLM was achieved via thin-film dispersion technique. The in vitro release of CLM compared with free CH was measured in phosphate buffer solution (PBS) containing 0.5%w/v sodium dodecyl sulphate (pH 6.8) while the pharmacokinetic and anti-CRF activity study was also conducted in rats. Moreover, the tissue distribution of CLM was investigated in the mice.

RESULTS

The CLM had particle size (PS) of 29.64 ± 0.71 nm, and encapsulation efficiency (EE) of 90.48 ± 1.22%w/w. The cumulative release rate of CH from the micellar system was significantly higher than that of the free CH (86%m/m vs. 15%m/m, p < 0.01). In vivo pharmacokinetic studies showed that the bioavailability of CLM after oral administration was substantially improved (about 3.4 times) compared with free drugs (p < 0.01). Also, it was observed that CLM accumulated well in the liver and brain. Moreover, in vitro renal podocytes study showed that CLM had better protection against renal podocyte damage than the free CH. In addition, CLM significantly (p < 0.01) reduced levels of blood urea nitrogen (BUN), kidney injury molecule-1 (Kim-1), and serum creatinine (SCr), which obviously improved kidney damage in rats with CRF.

CONCLUSIONS

Collectively, these findings suggest that mixed micelles may be used as a promising drug delivery system for oral bioavailability improvement and concomitantly enhance the anti-CRF activity of CH, as well as provide a basis for the clinical application of CH.

Enhanced oral bioavailability of Bisdemethoxycurcumin-loaded self-microemulsifying drug delivery system: Formulation design, in vitro and in vivo evaluation

In this study, we sought to overcome the poor solubility and bioavailability of bismethoxycurcumin (BDMC) by fabricating a BDMC-loaded self micro-emulsifying system (BDMC-SMEDDS). Solubility and compatibility tests, pseudo-ternary phase diagrams (PTPDs) as well as d-optimal concept was applied to design the formulation. The assessment of the prepared BDMC-SMEDDS in-vitro mainly included droplet size (DS) and entrapment efficiency (EE) determination, morphology, drug release and stability testing. Besides, the in vivo behavior was also evaluated after oral administration of BDMC-SMEDDS to rats. The optimal formulation was found to compose of Kolliphor EL (K-EL, emulsifier, 645.3 mg), PEG 400 (co-emulsifier, 147.2 mg), ethyl oleate (EO, oil, 207.5 mg) and BDMC (50 mg). The BDMC-SMEDDS with satisfactory stability had a mean size of 21.25 ± 3.23 nm and EE of 98.31 ± 0.32%. Roughly 70% of BDMC was released from BDMC-SMEDDS within 84 h compared with <20% from the free BDMC. More importantly, the in-vivo behavior of BDMC-SMEDDS showed that the AUC_(0-12h) and plasma concentration of BDMC increased substantially as compared to the free BDMC. Altogether, BDMC-SMEDDS has the potential to enhance the solubility and bioavailability of BDMC and could be applied in the clinics.