Establishing the pharmaceutical quality of Chinese herbal medicine: a provisional BCS classification

Flavonoids in the Spotlight: Bridging the Gap between Physicochemical Properties and Formulation Strategies

Flavonoids are hydroxylated polyphenols that are widely distributed in plants with diverse health benefits. Despite their popularity, the bioavailability of flavonoids is often overlooked, impacting their efficacy and the comparison of products. The study discusses the bioavailability-related physicochemical properties of flavonoids, with a focus on the poorly soluble compounds commonly found in dietary supplements and herbal products. This review sums up the values of pKa, log P, solubility, permeability, and melting temperature of flavonoids. Experimental and calculated data were compiled for various flavonoid subclasses, revealing variations in their physicochemical properties. The investigation highlights the challenges posed by poorly soluble flavonoids and underscores the need for enabling formulation approaches to enhance their bioavailability and therapeutic potential. Compared to aglycones, flavonoid glycosides (with sugar moieties) tend to be more hydrophilic. Most of the reviewed aglycones and glycosides exhibit relatively low log P and high melting points, making them "brick dust" candidates. To improve solubility and absorption, strategies like size reduction, the potential use of solid dispersions and carriers, as well as lipid-based formulations have been discussed.

Nanofibers of Glycyrrhizin/Hydroxypropyl-β-Cyclodextrin Inclusion Complex: Enhanced Solubility Profile and Anti-inflammatory Effect of Glycyrrhizin

Despite having a wide range of therapeutic advantages, glycyrrhizin (GL) has few commercial applications due to its poor aqueous solubility. In this study, we combined the benefits of hydroxypropyl β-cyclodextrin (HP-βCD) supramolecular inclusion complexes and electrospun nanofibers to improve the solubility and therapeutic potential of GL. A molecular inclusion complex containing GL and HP-βCD was prepared by lyophilization at a 1:2 molar ratio. GL and hydroxypropyl β-cyclodextrin inclusion complexes were also incorporated into hyaluronic acid (HA) nanofibers. Prepared NF was analyzed for physical, chemical, thermal, and pharmaceutical properties. Additionally, a rat model of carrageenan-induced hind paw edema and macrophage cell lines was used to evaluate the anti-inflammatory activity of GL-HP-βCD NF. The DSC and XRD analyses clearly showed the amorphous state of GL in nanofibers. In comparison to pure GL, GL-HP-βCD NF displayed improved release (46.6 ± 2.16% in 5 min) and dissolution profiles (water dissolvability ≤ 6 s). Phase solubility results showed a four-fold increase in GL solubility in GL-HP-βCD NF. In vitro experiments on cell lines showed that inflammatory markers like IL-1β, TNF-α, and IL-6 were significantly lower in GL-HP-βCD NF compared to pure GL (p < 0.01 and p < 0.05). According to in vivo results, the prepared nanofiber exhibits a better anti-inflammatory effect than pure GL (63.4% inhibition vs 53.7% inhibition). The findings presented here suggested that GL-HP-βCD NF could serve as a useful strategy for improving the therapeutic effects of GL.

Wedelolactone induces natural killer cell activity and the improvement to bioavailability using polysaccharides from Ligustri Lucidi Fructus

Wedelolactone (WDL) is the major bioactive component in Ecliptae Herba. This present study investigated the effects of WDL on natural killer cell functions and possible underlying mechanisms. It was proved that wedelolactone enhanced the killing ability of NK92-MI by upregulating the expression of perforin and granzyme B through the JAK/STAT signaling pathway. Additionally, wedelolactone could induce the migration of NK-92MI cells by promoting CCR7 and CXCR4 expressions. However, the application of WDL is limited due to poor solubility and bioavailability. Accordingly, this study investigated the impact of polysaccharides from Ligustri Lucidi Fructus (LLFPs) on WDL. The biopharmaceutical properties and pharmacokinetic characteristics were determined to compare WDL individually and in combination with LLFPs. The results showed that LLFPs could benefit the biopharmaceutical properties of WDL. Specifically, stability, solubility, and permeability were increased by 1.19-1.82-fold, 3.22-fold, and 1.08-fold higher than those of WDL alone, respectively. Furthermore, the pharmacokinetic study revealed that LLFPs could remarkably improve AUC_(0-t) (150.34 vs. 50.47 ng/mL ∗ h), t_1/2 (40.78 vs. 2.81 h), and MRT_(0-∞) (46.64 vs. 5.05 h) for WDL. In conclusion, WDL would be considered a potential immunopotentiator, and LLFPs could overcome the instability and insolubility, ultimately improving the bioavailability of this plant-derived phenolic coumestan.

Enhancement of the Bioavailability and Anti-Inflammatory Activity of Glycyrrhetinic Acid via Novel Soluplus®—A Glycyrrhetinic Acid Solid Dispersion

Glycyrrhetinic acid (GA) is an anti-inflammatory drug with potential for development. However, the poor solubility of GA in water leads to extremely low bioavailability, which limits its clinical applications. Solid dispersions have become some of the most effective strategies for improving the solubility of poorly soluble drugs. Soluplus^®, a non-cytotoxic amphiphilic solubilizer, significantly improves the solubility of BCS II drugs and improves the bioavailability of insoluble drugs. l-arginine (L-Arg) can be used as a small molecular weight excipient to assist in improving the solubility of insoluble drugs. In this study, we developed a new formulation for oral administration by reacting GA and L-Arg to form salts by co-solvent evaporation and then adding the polymer-solvent Soluplus^® with an amphiphilic chemical structure to prepare a solid dispersion GA-SD. The chemical and physical properties of GA-SD were characterized by DLS, TEM, XRD, FT-IR and TG. The anti-inflammatory activity of GA-SD was verified by LPS stimulation of RAW 267.5 cells simulating a cellular inflammation model, TPA-induced ear edema model in mice, and ethanol-induced gastric ulcer model. The results showed that the amide bond and salt formation of GA-SD greatly improved GA solubility. GA-SD effectively improved the anti-inflammatory effect of free GA in vivo and in vitro, and GA-SD had no significant effect on liver and kidney function, no significant tissue toxicity, and good biosafety. In conclusion, GA-SD with L-Arg and Soluplus^® is an effective method to improve the solubility and bioavailability of GA. As a safe and effective solid dispersion, it is a promising anti-inflammatory oral formulation and provides some references for other oral drug candidates with low bioavailability.

A review of transglycosylated compounds as food additives to enhance the solubility and oral absorption of hydrophobic compounds in nutraceuticals and pharmaceuticals

Transglycosylation has been used to modify the physicochemical properties of original compounds. As a result, transglycosylated compounds can form molecular aggregates in size ranges of a few nanometers in an aqueous medium when their concentrations exceed a specific level. Incorporating these hydrophobic compounds has been observed to enhance the solubility of hydrophobic compounds into aggregate structures. Thus, this review introduces four transglycosylated compounds as food additives that can enhance the solubility and oral absorption of hydrophobic compounds. Here, transglycosylated hesperidin, transglycosylated rutin, transglycosylated naringin, and transglycosylated stevia are the focus as representative substances. Significantly, we observed that amorphous formations containing hydrophobic compounds with transglycosylated compounds improved solubility and oral absorption compared to untreated hydrophobic compounds. Moreover, combining transglycosylated compounds with hydrophilic polymers or surfactants enhanced the solubilizing effects on hydrophobic compounds. Furthermore, the enhanced solubility of hydrophobic compounds improved their oral absorption. Transglycosylated compounds also influenced nanoparticle preparation of hydrophobic compounds as a dispersant. This study demonstrated the benefits of transglycosylated compounds in developing supplements and nutraceuticals of hydrophobic compounds with poor aqueous solubility.

An Overview on Dietary Polyphenols and Their Biopharmaceutical Classification System (BCS)

Polyphenols are natural organic compounds produced by plants, acting as antioxidants by reacting with ROS. These compounds are widely consumed in daily diet and many studies report several benefits to human health thanks to their bioavailability in humans. However, the digestion process of phenolic compounds is still not completely clear. Moreover, bioavailability is dependent on the metabolic phase of these compounds. The LogP value can be managed as a simplified measure of the lipophilicity of a substance ingested within the human body, which affects resultant absorption. The biopharmaceutical classification system (BCS), a method used to classify drugs intended for gastrointestinal absorption, correlates the solubility and permeability of the drug with both the rate and extent of oral absorption. BCS may be helpful to measure the bioactive constituents of foods, such as polyphenols, in order to understand their nutraceutical potential. There are many literature studies that focus on permeability, absorption, and bioavailability of polyphenols and their resultant metabolic byproducts, but there is still confusion about their respective LogP values and BCS classification. This review will provide an overview of the information regarding 10 dietarypolyphenols (ferulic acid, chlorogenic acid, rutin, quercetin, apigenin, cirsimaritin, daidzein, resveratrol, ellagic acid, and curcumin) and their association with the BCS classification.

Analgesic and Antipyretic Activities of Ethyl Acetate Fraction Tablet of Andrographis paniculata in Animal Models

Objectives

To determine the analgesic and antipyretic activities of a tablet derived from Andrographis paniculata ethyl acetate fraction (AS201-01) in animal models.

Methods

The tablet derived from AS201-01 contains an equivalent of 35 mg andrographolide per tablet. Analgesic activity was determined using an acetic acid-induced writhing test on adult male mice. A writhe was recorded by a stopwatch and was defined as the stretching of the abdomen and/or stretching of at least one hind limb. For the determination of antipyretic activity, pyrexia was induced by subcutaneous injection of 15% w/v Brewer's yeast into adult male rats. Rectal temperature was monitored at 1, 2, 3, and 4 hours after treatment.

Results

The results showed that the AS201-01 tablet had analgesic and antipyretic activity. In the acetic acid-induced writhing model, AS201-01 tablet exhibited significant analgesic effect with a 66.73% reduction in writhing response at a dose of 50 mg andrographolide/kg body weight compared to the negative control group. The tablet also showed a significant antipyretic effect. The maximum antipyretic effect was observed after the third hour of administration of the AS201-01 tablet at a dose of 100 mg andrographolide/kg body weight.

Conclusion

Tablet of Andrographis paniculata ethyl acetate fraction (AS201-01) exhibited analgesic and antipyretic activities.

The combination of HPLC and biological analysis to determine the quality markers and its structural composition of Eclipta prostrata L

INTRODUCTION

The diversity and complexity of components are important reasons for the unstable efficacy and safety of Chinese materia medica (CMM) in quality control. The good and stable quality control may be related to the quality markers with structural composition of multi-components.

OBJECTIVE

In the present study, we take Eclipta prostrata L. as a representative example. The 11 samples were collected from the different areas in China, and the discrepancy in bioactivity and chemical composition of these samples were compared. DOX (doxorubicin hydrochloride)-induced ICR mice were established for in vivo nephrotic syndrome experiments. The biochemical indicators including 24-h urine protein, triglyceride (TG), etc. were measured and the pathological change of kidney tissue was observed. MPC-5 cells damage model was induced to compare the difference of these samples in bio-activity. High-performance liquid chromatography (HPLC) method for 11 EEP (extract of Eclipta prostrata L.) samples were performed to analyse the content of the quality markers.

RESULTS

In vivo experiments, EEP could mitigate the content or activity of urine protein, TG, etc. compared with the positive group (TG content was 2.53 ± 0.39 mmol/L, urinary protein quantification on 35th day was 16.79 ± 2.32 mg). In vitro experiments, CCE (coumestans component of Ecliptae) and EEP had equivalent effects on biochemical indicators such as cell viability, etc. According to the HPLC analysis, the content of wedelolactone was 45.88% and demethylwedelolactone was 23.74% in CCE.

CONCLUSION

The CCE with a ratio of 2:1 can be considered as a quality marker of Eclipta prostrata L.. This research may provide a perspective for quality control of CMM.

Matrix effects of the hydroethanolic extract and the butanol fraction of calyces from Physalis peruviana L. on the biopharmaceutics classification of rutin

OBJECTIVES

The Biopharmaceutics Classification System (BCS) categorizes active pharmaceutical ingredients according to their solubility and permeability properties, which are susceptible to matrix or formulation effects. The aim of this research was to evaluate the matrix effects of a hydroethanolic extract of calyces from Physalis peruviana L. (HEE) and its butanol fraction (BF), on the biopharmaceutics classification of their major compound, quercetin-3-O-rutinoside (rutin, RU).

METHODS

Rutin was quantified by HPLC-UV, and Caco-2 cell monolayer transport studies were performed to obtain the apparent permeability values (P_app ). Aqueous solubility was determined at pH 6.8 and 7.4.

KEY FINDINGS

The P_app values followed this order: BF > HEE > RU (1.77 ± 0.02 > 1.53 ± 0.07 > 0.90 ± 0.03 × 10^-5  cm/s). The lowest solubility values followed this order: HEE > RU > BF (2.988 ± 0.07 > 0.205 ± 0.002 > 0.189 ± 0.005 mg/ml).

CONCLUSIONS

According to these results, rutin could be classified as BCS classes III (high solubility/low permeability) and IV (low solubility/low permeability), depending on the plant matrix. Further work needs to be done in order to establish how apply the BCS for research and development of new botanical drugs or for bioequivalence purposes.

Toward a better understanding of metabolic and pharmacokinetic characteristics of low-solubility, low-permeability natural medicines

Today, it is very challenging to develop new active pharmaceutical ingredients. Developing good preparations of well-recognized natural medicines is certainly a practical and economic strategy. Low-solubility, low-permeability natural medicines (LLNMs) possess valuable advantages such as effectiveness, relative low cost and low toxicity, which is shown by the presence of popular products on the market. Understanding the in vivo metabolic and pharmacokinetic characteristics of LLNMs contributes to overcoming their associated problems, such as low absorption and low bioavailability. In this review, the structure-based metabolic reactions of LLNMs and related enzymatic systems, cellular and bodily pharmacological effects and metabolic influences, drug-drug interactions involved in metabolism and microenvironmental changes, and pharmacokinetics and dose-dependent/linear pharmacokinetic models are comprehensively evaluated. This review suggests that better pharmacological activity and pharmacokinetic behaviors may be achieved by modifying the metabolism through using nanotechnology and nanosystem in combination with the suitable administration route and dosage. It is noteworthy that novel nanosystems, such as triggered-release liposomes, nucleic acid polymer nanosystems and PEGylated dendrimers, in addition to prodrug and intestinal penetration enhancer, demonstrate encouraging performance. Insights into the metabolic and pharmacokinetic characteristics of LLNMs may help pharmacists to identify new LLNM formulations with high bioavailability and amazing efficacy and help physicians carry out LLNM-based precision medicine and individualized therapies.

Improved delivery of natural alkaloids into lung cancer through woody oil-based emulsive nanosystems

Most antitumor ingredients found in nature have poor solubility. These ingredients are expected to have much better absorption and higher bioavailability than synthetic antitumor agents. Woody oil emulsive nanosystems carrying poorly soluble natural alkaloids were fabricated (evodiamine (EA) carried by fructus bruceae oil-based emulsive nanosystems, or EFEN). Fructus bruceae oil has two excipient-like properties (oil phase and stabilizer) that contribute to the formulation and one drug-like property (antitumor effects) that synergizes with the antitumor effect of EA. The properties of EFEN were compared with free EA, a blank nanoemulsion, an EA-loaded emulsive nanosystem, and a fructus bruceae oil-loaded emulsive nanosystem. For the first time, this suggests that increases in the sensitivity of lung cancer cells to poorly soluble natural alkaloids can be achieved by delivering drugs using woody oil-based emulsive nanosystems. In this study, woody oil-based emulsive nanosystems efficiently deliver poorly soluble natural alkaloids.

Pharmacokinetics and Safety of DW1029M, a Botanical Drug for the Treatment of Diabetic Nephropathy, Following Single Doses in Healthy Subjects

DW1029M is a botanical extract of Morus albalinne root bark and Puerariae radix that is used for the treatment of diabetic nephropathy. This study evaluated the safety and pharmacokinetics of DW1029M following its administration in healthy Korean subjects. We conducted a randomized, open-label, single-dose, crossover phase 1 clinical study. During each period, subjects received 300, 600, or 1200 mg oral doses of DW1029M. Plasma concentrations of puerarin, daidzin, and daidzein were analyzed using a liquid chromatography-tandem mass spectrometry. Six healthy male subjects completed the study. The maximum concentration of the drug in the plasma (C_max ) and area under the plasma drug concentration-time curve to the last measurable concentration (AUC_last ) for puerarin, daidzin, and daidzein were assessed after oral administration of DW1029M. No serious adverse events or clinically or statistically significant adverse events associated with any of the drug levels were observed. The results of the measurement of vital signs, electrocardiogram, laboratory tests, and physical examinations indicated that no clinically significant changes occurred during this study. The DW1029M tablet was safe and well tolerated over a single dose range of 300-1200 mg. This pharmacokinetic study of a botanical drug may aid in the development of DW1029M.

The Effect of Yokukansan, a Traditional Herbal Preparation Used for the Behavioral and Psychological Symptoms of Dementia, on the Drug-Metabolizing Enzyme Activities in Healthy Male Volunteers

The concomitant use of herb and prescription medications is increasing globally. Herb-drug interactions are therefore a clinically important problem. Yokukansan (YKS), a Japanese traditional herbal medicine, is one of the most frequently used herbal medicines. It is effective for treating the behavioral and psychological symptoms of dementia. We investigated the potential effects of YKS on drug-metabolizing enzyme activities in humans. An open-label repeat-dose study was conducted in 26 healthy Japanese male volunteers (age: 22.7±2.3 years) with no history of smoking. An 8-h urine sample was collected after a 150-mg dose of caffeine and a 30-mg dose of dextromethorphan before and after the administration of YKS (2.5 g, twice a day for 1 week). The activities of cytochrome P450 (CYP) 1A2, CYP2D6, CYP3A, xanthine oxidase (XO) and N-acetyltransferase 2 (NAT2) were assessed based on the urinary metabolic indices of caffeine and dextromethorphan, and the urinary excretion ratio of 6β-hydroxycortisol to cortisol. There were no statistically significant differences in the activities of the examined enzymes before or after the 7-d administration of YKS. Although further studies assessing the influence of YKS on the pharmacokinetics and pharmacodynamics of the substrates of the drug-metabolizing enzymes are needed to verify the present results, YKS is unlikely that a pharmacokinetic interaction will occur with concomitantly administered medications that are predominantly metabolized by the CYP1A2, CYP2D6, CYP3A, XO and NAT2.

Phospholipid-based solid drug formulations for oral bioavailability enhancement: A meta-analysis

Low bioavailability nowadays often represents a challenge in oral dosage form development. Solid formulations composed of drug and phospholipid (PL), which, upon contact with water, eventually form multilamellar liposomes (i.e. 'proliposomes'), are an emerging approach to solve such issue. Regarded as an 'improved' version of liposomes concerning storage stability, the potential and versatility of a range of such formulations for oral drug delivery have been extensively discussed. However, a systematic and quantitative analysis of the studies that applied solid PL for oral bioavailability enhancement is currently lacking. Such analysis is necessary for providing an overview of the research progress and addressing the question on how promising this approach can be on bioavailability enhancement. The current review performed a systematic search of references in three evidence-based English databases, Medline, Embase, and SciFinder, from the year of 1985 up till March 2015. A total of 112 research articles and 82 patents that involved solid PL-based formulations were identified. The majority of such formulations was intended for oral drug delivery (55%) and was developed to address low bioavailability issues (49%). A final of 54 studies that applied such formulations for bioavailability enhancement of 43 different drugs with poor water solubility and/or permeability were identified. These proof-of-concept studies with in vitro (n=31) and/or animal (n=23) evidences have been systematically summarized. Meta-analyses were conducted to measure the overall enhancement power (percent increase compared to control group) of solid PL formulations on drugs' solubility, permeability and oral bioavailability, which were found to be 127.4% (95% CI [86.1, 168.7]), 59.6% (95% CI [30.1, 89.0]), and 18.5% (95% CI [10.1, 26.9]) respectively. Correlations between the enhancement factors and in silico physiochemical properties of drugs were also performed to check if such approach can be used to identify the best candidates for oral solid PL formulation. In addition to scientific literature, 13 solid PL formulation-related patents that addressed the issue of low oral bioavailability have been identified and summarized; whereas no clinical study was identified from the current search. By providing systematic information and meta-analysis on studies that applied the principle of 'proliposomes' for oral bioavailability enhancement, the current review should be insightful for formulation scientists who wish to adopt the PL based approach to overcome the solubility, permeability and bioavailability issues of orally delivered drugs.

Rapid Discrimination for Traditional Complex Herbal Medicines from Different Parts, Collection Time, and Origins Using High-Performance Liquid Chromatography and Near-Infrared Spectral Fingerprints with Aid of Pattern Recognition Methods

As an effective method, the fingerprint technique, which emphasized the whole compositions of samples, has already been used in various fields, especially in identifying and assessing the quality of herbal medicines. High-performance liquid chromatography (HPLC) and near-infrared (NIR), with their unique characteristics of reliability, versatility, precision, and simple measurement, played an important role among all the fingerprint techniques. In this paper, a supervised pattern recognition method based on PLSDA algorithm by HPLC and NIR has been established to identify the information of Hibiscus mutabilis L. and Berberidis radix, two common kinds of herbal medicines. By comparing component analysis (PCA), linear discriminant analysis (LDA), and particularly partial least squares discriminant analysis (PLSDA) with different fingerprint preprocessing of NIR spectra variables, PLSDA model showed perfect functions on the analysis of samples as well as chromatograms. Most important, this pattern recognition method by HPLC and NIR can be used to identify different collection parts, collection time, and different origins or various species belonging to the same genera of herbal medicines which proved to be a promising approach for the identification of complex information of herbal medicines.

The Nutraceutical Bioavailability Classification Scheme: Classifying Nutraceuticals According to Factors Limiting their Oral Bioavailability

The oral bioavailability of a health-promoting dietary component (nutraceutical) may be limited by various physicochemical and physiological phenomena: liberation from food matrices, solubility in gastrointestinal fluids, interaction with gastrointestinal components, chemical degradation or metabolism, and epithelium cell permeability. Nutraceutical bioavailability can therefore be improved by designing food matrices that control their bioaccessibility (B*), absorption (A*), and transformation (T*) within the gastrointestinal tract (GIT). This article reviews the major factors influencing the gastrointestinal fate of nutraceuticals, and then uses this information to develop a new scheme to classify the major factors limiting nutraceutical bioavailability: the nutraceutical bioavailability classification scheme (NuBACS). This new scheme is analogous to the biopharmaceutical classification scheme (BCS) used by the pharmaceutical industry to classify drug bioavailability, but it contains additional factors important for understanding nutraceutical bioavailability in foods. The article also highlights potential strategies for increasing the oral bioavailability of nutraceuticals based on their NuBACS designation (B*A*T*).

Mechanism-based inhibitory and peroxisome proliferator-activated receptor α-dependent modulating effects of silybin on principal hepatic drug-metabolizing enzymes

Silybin, a major pharmacologically active compound in silymarin, has been widely used in combination with other prescriptions in the clinic to treat hepatitis and a host of other diseases. Previous studies suggested that silybin is a potential inhibitor of multiple drug-metabolizing enzymes (DMEs); however, the in vitro to in vivo translation and the mechanisms involved remain established. The aim of this study was to provide a mechanistic understanding of the regulatory effects of silybin on principal DMEs. Silybin (50 or 150 mg/kg/d) was administered to mice for a consecutive 14 days. The plasma and hepatic exposure of silybin were detected; the mRNA, protein levels, and enzyme activities of principal DMEs were determined. The results demonstrated that the enzyme activities of CYP1A2, CYP2C, CYP3A11, and UGT1A1 were significantly repressed, whereas little alteration of the mRNA and protein levels was observed. Silybin inhibits these DMEs in a mechanism-based and/or substrate-competitive manner. More importantly, silybin was found to be a weak agonist of peroxisome proliferator-activated receptor (PPAR)α, as evidenced from the molecular docking, reporter gene assay, and the targeting gene expression analysis. However, silybin could significantly compromise the activation of PPARα by fenofibrate, characterized with significantly repressed expression of PPARα targeting genes, including L-FABP, ACOX1, and UGT1A6. This study suggests that silybin, despite its low bioavailability, may inhibit enzyme activities of multiple DMEs in a mechanism-based mode, and more importantly, may confer significant drug-drug interaction with PPARα agonists via the repression of PPARα activation in a competitive mode.

Biopharmaceutics classification of puerarin and comparison of perfusion approaches in rats

The present study was conducted to characterize the biopharmaceutics classification system (BCS) category of puerarin in terms of intrinsic dissolution rate (IDR) and rat intestinal permeability and to investigate the poor intestinal absorption probably related to the drug metabolism in the gut wall of rats. Equilibrium solubility of puerarin was determined in various phosphate buffers and water, and IDR was estimated by measuring the dissolution of a non-disintegrating compact. Intestinal permeability (Peff and Pblood) of puerarin was determined using the technology of in situ single-pass intestinal perfusion (SPIP) and intestinal perfusion with venous sampling (IPVS) in fasted rats. Metabolism of puerarin in intestinal tissue was tested by S9 incubation in vitro. The aqueous solubility of puerarin in phosphate buffers and water was good with a maximum solubility of 7.56 mg/mL at pH 7.4. Obtained IDR values of puerarin were in the range of 0.360-1.088 mg/min/cm(2), with maximum and minimum IDR value of pH 7.4 and pH 4.0, respectively. The Peff was 1.252 × 10(-5)cm/s determined by SPIP and the Pblood was 0.068×10(-5)cm/s by IPVS in jejunum at puerarin 80 μg/mL. The metabolism rate of puerarin determined by the intestinal S9 fraction indicated that the gut wall metabolism of puerarin is one cause of poor absorption. According to the proposed classification of drugs and the results obtained from equilibrium solubility, IDR, Peff and Pblood, it is concluded that puerarin could be categorized IV drug of the BCS based on its low solubility and low intestinal permeability values.