Situ Single-pass Intestinal Perfusion Research Articles

Study of Absorption Characteristics of the Total Saponins from Radix Ilicis Pubescentis in an In Situ Single-Pass Intestinal Perfusion (SPIP) Rat Model by Using Ultra Performance Liquid Chromatography (UPLC).

In contrast to the extensively reported therapeutic activities, far less attention has been paid to the intestinal absorption of the total saponins from Radix Ilicis Pubescentis (in Chinese Mao-Dong-Qing, MDQ). This study aimed to investigate the intestinal absorption characteristics of ilexgenin A (C1), ilexsaponin A1 (C2), ilexsaponin B1 (C3), ilexsaponin B2 (C4), ilexsaponin B3 (DC1), and ilexoside O (DC2) when administrated with the total saponins from MDQ (MDQ-TS). An UPLC method for simultaneous determination of C1, C2, C3, C4, DC1, and DC2 in intestinal outflow perfusate was developed and validated. The absorption characteristics of MDQ-TS were investigated by evaluating the effects of intestinal segments, drug concentration, P-glycoprotein (P-gp) inhibitor (verapomil), endocytosis inhibitor (amantadine) and ethylene diamine tetraacetic acid (EDTA, tight junction modulator) on the intestinal transportation of MDQ-TS by using a single-pass intestinal perfusion (SPIP) rat model, and the influence of co-existing components on the intestinal transport of the six saponins was discussed. The results showed that effective apparent permeability (Papp) of C1, C2, C3, C4, and DC2 administrated in MDQ-TS form had no segment-dependent changes at low and middle dosage levels. C1, C2, C3, D4, DC1, and DC2 administrated in MDQ-TS form all exhibited excellent transmembrane permeability with Papp > 0.12 × 10−2 cm·min−1. Meanwhile, Papp and effective absorption rate constant (Ka) values for the most saponins showed concentration dependence and saturation characteristics. After combining with P-gp inhibitor of verapamil, Papp of C2, C3, and DC1 in MDQ-TS group was significantly increased up to about 2.3-fold, 1.4-fold, and 3.4-fold, respectively in comparison to that of non-verapamil added group. Verapamil was found to improve the absorption of C2, C3, and DC1, indicating the involvement of an active transport mechanism in the absorption process. Compared with the non-amantadine added group, the absorption of C1, C2, C4, DC1, and DC2 were decreased by 40%, 71%, 31%, 53%, and 100%, respectively. Papp for the six target compounds increased up to about 1.2–2.1-fold in comparison with the non-EDTA added, respectively. The gastrointestinal transport of MDQ-TS could be greatly promoted by EDTA, and inhibited by amantadine, implying that the intestinal absorption of MDQ-TS was by passive diffusion and endocytosis process. Compared with monomer administration group, the intestinal absorption of C3, C4, DC1, and DC2 was significantly improved by co-existing components in MDQ-TS, and the non-absorbable saponins of C4, DC1, and DC2 unexpectedly showed sufficient intestinal permeability with Papp > 0.12 × 10−2 cm·min−1. This suggested that compounds orally administrated in TCM extract forms displayed unique intestinal absorption characteristics different from those of monomers, and the enhancing intestinal absorption of MDQ-TS reflected a holistic and specific view of traditional Chinese medicines (TCMs).

Polymeric nanoparticles developed by vitamin E-modified aliphatic polycarbonate polymer to promote oral absorption of oleanolic acid

Oleanolic acid (OA) exhibited good pharmacological activities in the clinical treatment of hypoglycemia, immune regulation, acute jaundice and chronic toxic hepatitis. However, the oral delivery of OA is greatly limited by its inferior water solubility and poor intestinal mucosa permeability. Herein, we developed a novel polymeric nanoparticle (NP) delivery system based on vitamin E modified aliphatic polycarbonate (mPEG-PCC-VE) to facilitate oral absorption of OA. OA encapsulated mPEG-PCC-VE NPs (OA/mPEG-PCC-VE NPs) showed uniform particle size of about 170 nm with high drug loading capability (8.9%). Furthermore, the polymeric mPEG-PCC-VE NPs, with good colloidal stability and pH-sensitive drug release characteristics, significantly enhanced the in vitro dissolution of OA in the alkaline medium. The in situ single pass intestinal perfusion (SPIP) studies performed on rats demonstrated that the OA/mPEG-PCC-VE NPs showed significantly improved permeability in the whole intestinal tract when compared to OA solution, especially for duodenum and colon. As a result, the in vivo pharmacokinetics study indicated that the bioavailability of OA/mPEG-PCC-VE NPs showed 1.5-fold higher than commercially available OA tablets. These results suggest that mPEG-PCC-VE NPs are a promising platform to facilitate the oral delivery of OA.

Glucosamine modulates propranolol pharmacokinetics via intestinal permeability in rats

Propranolol (PROP) undergoes extensive first-pass metabolism by the liver resulting in a relatively low bioavailability (13–23%); thus, multiple oral doses are required to achieve therapeutic effect. Since some studies have reported that glucosamine (GlcN) can increase the bioavailability of some drugs, therefore, it is aimed to study whether GlcN can change the pharmacokinetic parameters of PROP, thus modulating its bioavailability. When PROP was orally co-administered with GlcN (200mg/kg) to rats, PROP area under curve (AUC) and maximum concentration (Cmax) were significantly decreased by 43% (p<0.01) and 33% (p<0.05), respectively. In line with the in vivo results, in silico simulations confirmed that GlcN decreased rat intestinal effective permeability (Peff) and increased PROP clearance by 50%. However, in situ single pass intestinal perfusion (SPIP) experiments showed that GlcN significantly increased PROP serum levels (p<0.05). Furthermore, GlcN decreased PROP disposition/distribution into cultured hepatocytes in concentration dependent manner. Such change in the interaction pattern between GlcN and PROP might be attributed to the environment of the physiological buffer used in the in vitro experiments (pH7.2) versus the oral administration and thus, enhanced PROP permeability. Nevertheless, such enhancement was not detected when everted gut sacks were incubated with both drugs at the same pH in vitro. In conclusion, GlcN decreased PROP serum levels in rats in a dose-dependent manner. Such interaction might be attributed to decreased intestinal permeability and enhanced clearance of PROP in the presence of GlcN. Further investigations are still warranted to explain the in vitro inhibitory action of GlcN on PROP hepatocytes disposition and the involvement of GlcN in the intestinal and hepatic metabolizing enzymes of PROP at different experimental conditions.

Assessment of absorption of four lignan constituents of JingNing particles in rat gut using &lt;i&gt;in situ&lt;/i&gt; single-pass intestinal perfusion

Purpose: To study small intestinal absorption of schisadrol A, schisandrol B, schizandrin A and schisandrin B in JingNing particles using in situ single-pass intestinal perfusion (SPIP).Methods: Absorption rate constant (Ka) and apparent permeability (Papp) of the drugs at different concentrations in various parts of rat small intestine (duodenum, jejunum and ileum) were determined using SPIP. JingNing particles were also perfused in situ at different pH in the entire rat intestine. Ethanol extract of Schisandra chinensis (standard) at low concentration was perfused in the duodenum for comparison with extract of JingNing particles.Results: The order of apparent permeability of the four lignans was schisandrol A &lt; schisandrol B &lt; schizandrin A &lt; schisandrin B. Ka and Papp values of the four lignans in JingNing particles were concentration-dependent. Absorption increased in the rank order: ileum &gt; duodenum &gt; jejunum. Optimum absorption pH was 6.50. Polygala tenuifolia extract and volatile oil of Rhizoma acori tatarinowii significantly (p &lt; 0.05) enhanced the absorption of the four lignans.Conclusion: The four lignans were well absorbed in the intestinal tract, particularly the ileum, probably through carrier-mediated transport. The alcohol extract of Polygala tenuifolia and volatile oil of Rhizoma acori graminei enhanced the absorption of the four lignans.Keywords: JingNing, Intestinal absorption, Polygala tenuifolia, Rhizoma acori graminei, Lignans, Schisandrol, Schisandrin, Single-pass intestinal perfusion

Comparison of intestinal permeability and p-glycoprotein effects on the intestinal absorption of enantiomers of 2-(2-hydroxypropanamido) benzoic acid in rats.

The purpose of this study was to compare intestinal permeability between enantiomers of 2-(2-hydroxypropanamido) benzoic acid ((R)-/(S)-HPABA), a marine-derived antiinflammatory drug, using an in situ single-pass intestinal perfusion (SPIP) model in rats. Concentrations, isolated regions of small intestine, and p-glycoprotein (P-gp) inhibitor were performed to investigate their influences on the intestinal absorption of (R)-/(S)-HPABA. In addition, a molecular docking method was performed to illustrate our prediction. The absorption rate coefficients (Ka ) and permeability values (Peff ) of (R)-/(S)-HPABA were calculated. The permeability of (S)-HPABA was significantly (P<0.01) higher than that of (R)-HPABA in jejunum, and ileum permeability of (R)-/(S)-HPABA appeared best in ileum; the investigated concentrations ranged from 20 to 80μg/mL, Ka and Peff values of (R)-/(S)-HPABA increased linearly; in the presence of P-gp inhibitor (verapamil), Peff values of two enantiomers were increased significantly; and the effect of P-gp on absorption of (R)-HPABA is stronger than that of (S)-HPABA in ileum segment. Based on these results, carrier-mediated transport or passive transport combined with carrier-mediated transport seems to be the mechanism for intestinal absorption of (R)-/(S)-HPABA, and (R)-/(S)-HPABA may be recognized as the P-gp substrate. In addition, the intestinal permeability of (S)-HPABA is higher than that of (R)-HPABA.

Formulation optimization of Docetaxel loaded self-emulsifying drug delivery system to enhance bioavailability and anti-tumor activity.

Poor bioavailability of Docetaxel (DCT) arising due to its low aqueous solubility and permeability limits its clinical utility. The aim of the present study was to develop DCT loaded self-emulsified drug delivery systems (D-SEDDS) and evaluate its potential ability to improve the oral bioavailability and therapeutic efficacy of DCT. D-SEDDS were characterized for their in vitro antitumor activity, in situ single pass intestinal perfusion (SPIP), bioavailability, chylomicron flow blocking study and bio-distribution profile. The D-SEDDS were prepared using Capryol 90, Vitamin E TPGS, Gelucire 44/14 and Transcutol HP with a ratio of 32.7/29.4/8.3/29.6 using D-Optimal Mixture Design. The solubility of DCT was improved upto 50 mg/mL. The oral bioavailability of the D-SEDDS in rats (21.84 ± 3.12%) was increased by 3.19 fold than orally administered Taxotere (6.85 ± 1.82%). The enhanced bioavailability was probably due to increase in solubility and permeability. In SPIP, effective permeability of D-SEDDS was significantly higher than Taxotere. D-SEDDS showed 25 fold more in vitro cytotoxic activity compared to free DCT. Chylomicron flow blocking study and tissue distribution demonstrated the intestinal lymphatic transport of D-SEDDS and higher retention in tumor than Taxotere. The data suggests that D-SEDDS showed desired stability, enhanced oral bioavailability and in vitro antitumor efficacy.

Evaluation for impacts of gut wall metabolism of multiple components in Chuanxiong Rhizoma during intestinal absorption with S9 incubation

The information of drug deposition in the intestine is required in the study for the drug absorption in biopharmaceutics classification system (BCS). To illustrate the impacts of gut wall metabolism on the absorption, metabolism of multiple components in Chuanxiong Rhizoma in gut wall was tested by rat S9 incubation in vitro. The chemical fingerprint technology was used in this study to simultaneously detect multiple components in Chuanxiong, and peak areas before and after S9 incubation were compared. The results showed that senkyunolide I and several constituents were metabolized by gut wall, and one new metabolite was founded. However, ferulic acid and other compounds remained unchanged after incubation. Therefore, the subsequent intestinal permeability of multiple components in Chuanxiong that were not metabolized in the intestine was suggested to be detected directly by in situ single-pass intestinal perfusion (SPIP).Nonetheless, the intestinal permeability of the constituents that were metabolized in the intestine shall be explored by appropriate approaches.

Study on property of biopharmaceutics classification system of berberine in Huanglian decoction

The study of single component in the multicomponent environment is one of the basic researches for biopharmaceutics classification system of Chinese materia medica (CMMBCS). That is to say, the classification research shall be based on the respective lift of solubility and permeability in the multicomponent environment, besides solubility and intestinal permeability of the single component. We chose berberine as the main research object to investigate the changes of its solubility and intestinal permeability in Huanglian decoction. Shake-flask and HPLC were used to detect the solubility of berberine in different pH buffer solutions and different concentrations of Huanglian decoction. In situ single-pass intestinal perfusion (SPIP) and intestinal perfusion with venous sampling (IPVS) were carried out to study berberine's intestinal absorption and absorption into blood, respectively.

Systematic development of optimized SNEDDS of artemether with improved biopharmaceutical and antimalarial potential

The current studies entail systematic development of self-nanoemulsifying drug delivery systems (SNEDDS) containing medium-chain triglycerides (MCTs) and long-chain triglycerides (LCTs) for augmenting the biopharmaceutical performance of artemether. Equilibrium solubility and pseudoternary phase diagram studies facilitated selection of Captex 355 and Ethyl oleate as MCTs and LCTs, and Cremophor RH 40 and Tween 80 as surfactants, while Transcutol HP as cosolvent for formulating the SNEDDS. Systematic optimization was performed employing the Box–Behnken design taking concentrations of lipid, surfactant and cosolvent as the critical material attributes (CMAs), while evaluating for globule size, emulsification time, dissolution efficiency and permeation as the critical quality attributes (CQAs). In situ single pass intestinal perfusion (SPIP) studies in Wistar rats substantiated significant augmentation in the absorption (5- to 6-fold) and permeation (4- to 5-fold) parameters from the optimized MCT and LCT-SNEDDS vis-à-vis the pure drug. In vivo pharmacodynamic studies in Plasmodium berghi infected laca mice exhibited superior reduction in the levels of percent parasitemia, SGOT, SGPT and bilirubin, followed by higher survival rate of the animals by optimized MCT-SNEDDS followed by LCT-SNEDDS vis-à-vis the pure drug, which was subsequently ratified through histopathological examination of liver tissues. Overall, the studies construed successful development of the optimized SNEDDS of artemether with distinctly improved biopharmaceutical and antimalarial potential.

Core-matched encapsulation of an oleate prodrug into nanostructured lipid carriers with high drug loading capability to facilitate the oral delivery of docetaxel

Nanostructured lipid carriers (NLC) have been considered as promising vehicles for oral delivery of taxanes, such as docetaxel (DTX). However, the low drug loading capability (∼5%, w/w) has greatly limited their clinical application. In response to this challenge, a novel lipophilic oleate prodrug of DTX (DTX-OA) was synthesized and efficiently encapsulated in NLC using core-match technology, in which liquid lipid (OA) was used as core matrix to enhance compatibility with DTX-OA. DTX-OA-NLC showed uniform particle size of about 100nm with markedly high drug loading capability (∼23% of DTX, w/w) compared with DTX-NLC (∼5%, w/w). Besides, DTX-OA-NLC showed better colloidal stability and slower drug release property compared with DTX-NLC. The prepared NLC could be accumulated more easily in MDCK cells than drug solution, and clathrin-mediated endocytosis was the main endocytosis pathway. In situ single-pass intestinal perfusion (SPIP) and intestinal biodistribution studies demonstrated the improved membrane permeability and intestinal wall bioadhesion of NLCs. The bioavailability of DTX-OA-NLC showed 4.04-fold and 2.06-fold higher than DTX solution and DTX-NLC, respectively. These results suggest that the core-matched prodrug-NLC is a promising platform to facilitate the oral delivery of DTX.

Potential Mechanism of Herb-Drug Interaction Mediated by &amp;lt;i&amp;gt;Angelica dahurica&amp;lt;/i&amp;gt;: Inhibition on CYP3A Enzymes in Rats

Angelica dahurica is commonly referred to as ‘Baizhi’ in China and has been noted for its therapeutic significance. The major active ingredients of Angelica dahurica is coumarin, which is reported as a kind of potent inhibitor of cytochrome P450 enzymes (CYP450s). The aim of this study was to investigate the inhibition of CYP3A enzymes by total coumarin extract (TCE) obtained from dried root of Angelica dahurica by using in situ single pass intestinal perfusion (SPIP) and in situ liver perfusion in rats. When midazolam (MDZ) which is a substrate of CYP3A co-perfused with TCE (198 μg/mL) from Baizhi in duodenum and ileum segments, the Peff of MDZ has increased significantly compared with the MDZ single perfused group (p 0.05) (n = 6). During in situ liver perfusion study, the results demonstrated that, 3 days oral administration of TCE obtained from Baizhi could significantly reduce the elimination rate of MDZ in the perfusate (p Angelica dahurica extract co-administrated with drugs which are the substrates of CYP3A, much more attention should be paid rather than that of other CYP450 enzymes. These findings may facilitate in predicting possible herb-drug interactions (HDIs) when Angelica dahurica is used in combination with other drugs, and decrease the incidence of the CYP450-mediated HDIs.

Study on intestinal absorption of ingredients from different compatibilities of Shaoyao Gancao decoction

To study the compatible mechanisms and compatible proportion of Shaoyao Gancao decoction, the intestinal absorption of main ingredients in Shaoyao Gancao decoction SG11 (Baishao-Zhigancao 1: 1) , SG31 (Baishao-Zhigancao 3: 1), Baishao water decoction S and Zhigancao (G) were investigated and compared using in vitro everted intestinal sac model and in situ single pass intestinal perfusion (SPIP) model. The concentration of paeoniflorin (PF), liquiritin (LQ) and mono-ammonium glycyrrhizinate (GL) in test samples and samples of intestinal sac and intestinal perfusion was determined by HPLC. The intestinal absorptive amount and absorption parameters were calculated. Results showed that in the everted intestinal sac model, three ingredients could be absorbed by duodenum, jejunum and ileum, and the absorption in the jejunum was best for all 3 ingredients. The absorption rate of three ingredients in SG11 was significantly higher than that in single decoction (P < 0.05), but had no significant difference compared with SG31. In SPIP model, the absorption rate constant K(a), the apparent absorption coefficient P(app) and the absorption rate of three ingredients in SG11 were significantly higher than those in single decoction. Parameters of PF and GL in SG11 were significantly higher than those in SG31, but had no differences of LQ. It proved that the compatibility of Baishao and Zhigancao could improve the intestinal absorption of PF, LQ and GL. The absorption of each ingredient in SG11 was better than that in SG31.

Comparative pharmacokinetics of arctigenin in normal and type 2 diabetic rats after oral and intravenous administration

Arctigenin is the main active ingredient of Fructus Arctii for the treatment of type 2 diabetes. In this study, the pharmacokinetics of arctigenin in normal and type 2 diabetic rats following oral and intravenous administration was investigated. As compared to normal rats, Cmax and AUC0–10h values of oral arctigenin in diabetic rats increased by 356.8% and 223.4%, respectively. In contrast, after intravenous injection, the Cmax and AUC0–10h values of arctigenin showed no significant difference between diabetic and normal rats. In order to explore how the bioavailability of oral arctigenin increased under diabetic condition, the absorption behavior of arctigenin was evaluated by in situ single-pass intestinal perfusion (SPIP). The results indicated that arctigenin was a substrate of P-glycoprotein (P-gp). The absorption difference of arctigenin in the normal and diabetic rats could be eliminated by the pretreatment of classic P-gp inhibitor verapamil, suggesting that P-gp might be the key factor causing the absorption enhancement of arctigenin in diabetic rats. Further studies revealed that the uptake of rhodamine 123 (Rho123) in diabetic rats was significantly higher, indicating that diabetes mellitus might impair P-gp function. Consistently, a lower mRNA level of P-gp in the intestine of diabetic rats was found. In conclusion, the absorption of arctigenin after oral administration was promoted in diabetic rats, which might be partially attribute to the decreased expression and impaired function of P-gp in intestines.

Raltegravir permeability across blood-tissue barriers and the potential role of drug efflux transporters.

The objectives of this study were to investigate raltegravir transport across several blood-tissue barrier models and the potential interactions with drug efflux transporters. Raltegravir uptake, accumulation, and permeability were evaluated in vitro in (i) P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), multidrug resistance-associated protein 1 (MRP1), or MRP4-overexpressing MDA-MDR1 (P-gp), HEK-ABCG2, HeLa-MRP1, or HEK-MRP4 cells, respectively; (ii) cell culture systems of the human blood-brain (hCMEC/D3), mouse blood-testicular (TM4), and human blood-intestinal (Caco-2) barriers; and (iii) rat jejunum and ileum segments using an in situ single-pass intestinal perfusion model. [(3)H]Raltegravir accumulation by MDA-MDR1 (P-gp) and HEK-ABCG2-overexpressing cells was significantly enhanced in the presence of PSC833 {6-[(2S,4R,6E)-4-methyl-2-(methylamino)-3-oxo-6-octenoic acid]-7-L-valine-cyclosporine}, a P-gp inhibitor, or Ko143 [(3S,6S,12aS)-1,2,3,4,6,7,12,12a-octahydro-9-methoxy-6-(2-methylpropyl)-1,4-dioxopyrazino[1',2':1,6]pyrido[3,4-b]indole-3-propanoic acid 1,1-dimethylethyl ester], a BCRP inhibitor, suggesting the inhibition of a P-gp- or BCRP-mediated efflux process, respectively. Furthermore, [(3)H]raltegravir accumulation by human cerebral microvessel endothelial hCMEC/D3 and mouse Sertoli TM4 cells was significantly increased by PSC833 and Ko143. In human intestinal Caco-2 cells grown on Transwell filters, PSC833, but not Ko143, significantly decreased the [(3)H]raltegravir efflux ratios. In rat intestinal segments, [(3)H]raltegravir in situ permeability was significantly enhanced by the concurrent administration of PSC833 and Ko143. In contrast, in the transporter inhibition assays, raltegravir (10 to 500 μM) did not increase the accumulation of substrate for P-gp (rhodamine-6G), BCRP ([(3)H]mitoxantrone), or MRP1 [2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF)] by MDA-MDR1 (P-gp)-, HEK-ABCG2-, or HeLa-MRP1-overexpressing cells, respectively. Our data suggest that raltegravir is a substrate but not an inhibitor of the drug efflux transporters P-gp and BCRP. These transporters might play a role in the restriction of raltegravir permeability across the blood-brain, blood-testicular, and blood-intestinal barriers, potentially contributing to its low tissue concentrations and/or low oral bioavailability observed in the clinic setting.

Effect of diosmin on the intestinal absorption and pharmacokinetics of fexofenadine in rats

BackgroundDiosmin is a natural flavone glycoside, a potent P-glycoprotein (P-gp) inhibitor in cultured cells and have the potential to alter the bioavailability of P-gp substrate drugs. However, the interaction between diosmin and fexofenadine is unreported. Hence, the present study was performed to investigate the effect of diosmin on the intestinal absorption and pharmacokinetics of fexofenadine, a P-gp substrate in rats. MethodsFexofenadine intestinal transport and permeability were evaluated by in vitro non-everted sac and in situ single pass intestinal perfusion (SPIP) studies. These results were confirmed by an in vivo pharmacokinetic study of oral administered fexofenadine (10mg/kg) in rats. ResultsThe intestinal transport and apparent permeability (Papp) of fexofenadine were significantly increased in duodenum, jejunum and ileum of diosmin pretreated group as compared with the control. Similarly effective permeability (Peff) of fexofenadine was increased significantly in ileum of diosmin pretreated group as compared with control. In comparison with control, pretreatment with diosmin significantly increased peak plasma concentration (Cmax) and area under the concentration–time curve (AUC), while there was no significant change was observed in half life (T1/2), time to reach peak plasma concentration (Tmax) and elimination rate constant (Kel) of fexofenadine. ConclusionsDiosmin significantly enhanced the oral bioavailability of fexofenadine by the inhibition of P-gp mediated drug efflux during the intestinal absorption. Co-administration of diosmin with fexofenadine can reduce the dosage and results in reduced side effects of fexofenadine. The clinical relevance of this interaction should be further evaluated in human subjects.

Absorption characteristics of the total alkaloids from Mahonia bealei in an in situ single-pass intestinal perfusion assay

AimTo investigate the absorption characteristics of the total alkaloids from Mahoniae Caulis (TAMC) through the administration of monterpene absorption enhancers or protein inhibitors. MethodThe absorption behavior was investigated in an in situ single-pass intestinal perfusion (SPIP) assay in rats. ResultsThe intestinal absorption of TAMC was much more than that of a single compound or a mixture of compounds (jatrorrhizine, palmatine, and berberine). Promotion of absorption by the bicyclic monoterpenoids (borneol or camphor) was higher than by the monocyclic monoterpenes (menthol or menthone), and promotion by compounds with a hydroxyl group (borneol or menthol) was higher than those with a carbonyl group (camphor or menthone). The apparent permeability coefficient (Papp) of TAMC was increased to 1.8-fold by verapamil, while it was reduced to one half by thiamine. The absorption rate constant (Ka) and Papp of TAMC were unchanged by probenecid and pantoprazole. ConclusionThe intestinal absorption characteristics of TAMC might be passive transport, and the intestinum tenue was the best absorptive site. In addition, TAMC might be likely a substrate of P-glycoprotein (P-gp) and organic cation transporters (OCT), rather than multidrug resistance protein (MRP) and breast cancer resistance protein (BCRP). Compared with a single compound and a mixture of compounds, TAMC was able to be absorbed in the blood circulation effectively.

Comparison of two approaches of intestinal absorption by puerarin

IntroductionEverted gut sac (EGS) and in situ single-pass intestinal perfusion (SPIP) have been widely used in the study of drug absorption and biopharmaceutical classification systems (BCS). Furthermore, they could also be applied in the research of drug intestinal first-pass metabolism. Since most of Chinese herbal medicines (CHMs) are orally administrated, it is necessary to study the permeability of active ingredients of CHMs. Thus, we attempted to apply the EGS and SPIP models to study the permeability of puerarin, one of the active marker compounds (AMCs) of Puerariae Radix. MethodsIn the present study, three rat models of ex vivo and in situ, EGS, SPIP, and in situ intestinal perfusion with venous sampling (IPVS), were established to determine the permeability coefficient of puerarin. The apparent permeability coefficient (Papp) was obtained by EGS. The SPIP model was used to determine the effective permeability coefficient (Peff) in different intestinal segments. The blood permeability coefficient (Pblood) was determined by IPVS. Puerarin concentration of perfusion and blood samples were measured by HPLC. ResultsPuerarin could filter into EGS incubated in aqueous extract of Puerariae Radix or puerarin solution. In the SPIP experiment, the concentration effect on Peff was observed in the ileum, but not in the other three intestinal segments. The Pblood was 0.068±0.002×10−5cm/s and was 16-fold lower than the Peff (1.114±0.153×10−5cm/s) in the IPVS experiment at 80μg/mL puerarin. As expected, the Peff (1.24±0.11×10−5cm/s) in SPIP did not differ from the Peff in IPVS. The Papp was 0.199×10−5cm/s at 1200μg/mL puerarin, 10-fold lower than Peff (2.047±0.116×10−5cm/s) in SPIP. DiscussionThree models for permeability were successfully practiced in the study of puerarin absorption and our research strategy will be useful for herbal constituent absorption in the future.

Optimized PLGA nanoparticle platform for orally dosed trans-resveratrol with enhanced bioavailability potential

Background: Trans-resveratrol (t-RVT) is a potent antioxidant. The drug suffers enterohepatic recirculation and extensive first-pass metabolism by CYP3A4 in liver, resulting in very low bioavailability (almost zero).Objective: The current studies entail a novel formulation approach to develop systematically optimized (OPT) nanoparticles (NPs) to enhance the oral bioavailability potential using poly (dl-lactide-co-glycolide) (PLGA) of t-RVT and overcome enterohepatic recirculation.Methods: T-RVT-loaded PLGA NPs were prepared by nanoprecipitation method. Delineating the NP regions, the amounts of polymer and emulsifier were selected as the critical factors for systematically formulating the OPT NPs employing 32 central composite design. The pharmacokinetics, in vivo biodistribution and in situ single-pass intestinal perfusion (SPIP) studies of OPT formulation were investigated in male Wistar rats.Results: Augmentation in the values of Ka (7.17-fold) and AUC0 – ∞ (10.6-fold) indicated significant enhancement in the rate and extent of bioavailability by the OPT formulation compared to pure drug and marketed product. OPT formulation showed a 2.78-fold rise in the values of t-RVT concentrations in liver. In situ SPIP studies ascribed the significant enhancement in absorptivity and permeability parameters of OPT NPs to transport through the Peyer's patches. Successful establishment of in vitro/in vivo correlation substantiated the judicious choice of the in vitro dissolution milieu for simulating the in vivo conditions.Conclusion: The studies, therefore, could provide another useful tool for successful development of t-RVT NPs and an in vivo approach to designate nanoparticulate system of t-RVT with distinctly improved bioavailability and to overcome enterohepatic recirculation.

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.

Trans-resveratrol self-nano-emulsifying drug delivery system (SNEDDS) with enhanced bioavailability potential: optimization, pharmacokinetics and in situ single pass intestinal perfusion (SPIP) studies

Trans-resveratrol (t-RVT) is a potent antioxidant. By virtue of extensive pre-systemic metabolism and existence of enterohepatic recirculation, t-RVT bioavailability is almost zero. The current study aimed to develop self-nanoemulsifying drug delivery systems (SNEDDS) using long-chain triglycerides (LCTs) of t-RVT in an attempt to circumvent such obstacles. Equilibrium solubility studies indicated the choice of Lauroglycol FCC as lipid, and of Labrasol and Transcutol P as surfactants, for formulating the SNEDDS. Ternary phase diagrams were constructed to select the areas of nanoemulsions, and the amounts of lipid (X1) and surfactant (X2) as the critical factor variables. The SNEDDS were optimized using 32 central composite design (CCD) and the optimized formulation (OPT) located using overlay plot. The nanometer size range and high negative values of zeta potential depicted non-coalescent nature of the SNEDDS. Optimized formulation indicated marked improvement in drug release profile vis-à-vis pure drug. Cloud point determination and accelerated stability studies ascertained the stability of OPT. Augmentation in the values of Ka (3.29-fold) and AUC (4.31-fold) indicated significant enhancement in the rate and extent of bioavailability by the OPT compared with pure drug. In situ perfusion (SPIP) studies in Wistar rats construed remarkable enhancement in the absorptivity and permeability parameters of SNEDDS vis-à-vis the pure drug. Successful establishment of level A of in vitro/in vivo correlation substantiated the judicious choice of the in vitro dissolution milieu for simulating the in vivo conditions. The present study, therefore, reports the successful development of SNEDDS with distinctly enhanced bioavailability of t-RVT.