Situ Single-pass Intestinal Perfusion Research Articles

In vitro evaluation and in situ intestinal absorption characterisation of paeoniflorin nanoparticles in a rat model.

Purpose: the aim of this study was to improve the stability and bioavailability of paeoniflorin (PF) by using nanoparticle encapsulation technology. Methods: paeoniflorin nanoparticles (PF NPs) were prepared with PLGA as the carrier using the compound emulsion method. The nanoparticles were characterised by using a Malvern laser particle sizer, transmission electron microscope (TEM), X-ray diffraction (XRD) analyser, and Fourier-transform infrared (FT-IR) spectrometry. The PF NPs were subjected to a series of stability investigations (such as for 4 °C storage stability, pH stability, and thermal stability), lyophilisation protection technology investigations, and in vitro release studies. Finally, the intestinal absorption properties of PF and PF NPs were studied by the in situ single-pass intestinal perfusion (SPIP) rat model, using the effective permeability coefficient (P eff) and the absorption rate constant (K a) as relevant indexes. Results: the prepared nanoparticles had a particle size of 105.0 nm with blue opalescent, rounded morphology, uniform size, good stability and slow release. We found that 4% alginate was the best lyoprotectant for the PF NPs. In the intestinal absorption experiments, P eff was higher for the PF NPs group compared with the original PF material drug group in all intestinal segments (P < 0.05), and the absorption rate constant K a increased with the increase in the drug concentration. Conclusion: the nanoparticles produced by this method have good stability and a slow-release effect; they can thus improve the absorption of PF in rat intestines, helping improve the stability and bioavailability of PF and enhancing its pharmacological effects.

Quantitative Investigation of Intestinal Drug Absorption Enhancement by Drug-Rich Nanodroplets Generated via Liquid-Liquid Phase Separation.

Drug-rich droplets formed through liquid-liquid phase separation (LLPS) have the potential to enhance the oral absorption of drugs. This can be attributed to the diffusion of these droplets into the unstirred water layer (UWL) of the gastrointestinal tract and their reservoir effects on maintaining drug supersaturation. However, a quantitative understanding of the effect of drug-rich droplets on intestinal drug absorption is still lacking. In this study, the enhancement of intestinal drug absorption through the formation of drug-rich droplets was quantitatively evaluated on a mechanistic basis. To obtain fenofibrate (FFB)-rich droplets, an amorphous solid dispersion (ASD) of FFB/hypromellose (HPMC) was dispersed in an aqueous medium. Physicochemical characterization confirmed the presence of nanosized FFB-rich droplets in the supercooled liquid state within the FFB/HPMC ASD dispersion. An in situ single-pass intestinal perfusion (SPIP) assay in rats demonstrated that increased quantities of FFB-rich nanodroplets enhanced the intestinal absorption of FFB. The effective diffusion of FFB-rich nanodroplets through UWL would partially contribute to the improved FFB absorption. Additionally, confocal laser scanning microscopy (CLSM) of cross sections of the rat intestine after the administration of fluorescently labeled FFB-rich nanodroplets showed that these nanodroplets were directly taken up by small intestinal epithelial cells. Therefore, the direct uptake of drug-rich nanodroplets by the small intestine is a potential mechanism for improving FFB absorption in the intestine. To quantitatively evaluate the impact of FFB-rich droplets on the FFB absorption enhancement, we determined the apparent permeabilities of the FFB-rich nanodroplets and dissolved FFB based on the SPIP results. The apparent permeability of the FFB-rich nanodroplets was 110-130 times lower than that of dissolved FFB. However, when the FFB-rich nanodroplet concentration was several hundred times higher than that of dissolved FFB, the FFB-rich nanodroplets contributed significantly to FFB absorption improvement. The present study highlights that drug-rich nanodroplets play a direct role in enhancing drug absorption in the gastrointestinal tract, indicating their potential for further improvement of oral absorption from ASD formulations.

Improving intestinal absorption and antibacterial effect of florfenicol via nanocrystallisation technology

To study the effects of nanocrystallisation technology on the intestinal absorption properties and antibacterial activity of florfenicol (FF). The florfenicol nanocrystals (FF-NC) were prepared by wet grinding and spray drying. Additionally, changes in particle size, charge, morphology, and dissolution of FF-NC in the long-term stability were monitored by laser particle sizer, TEM, SEM, paddle method, and the structure of FF-NC powder was characterised by nuclear magnetic resonance (NMR) test. The antibacterial activity, intestinal absorption and intestinal histocompatibility of FF-NC were investigated by the stiletto, mini broth dilution susceptibility test, in situ single-pass intestinal perfusion (SPIP) and haematoxylin–eosin (H–E) staining. After 12 months of storage, the particle size and zeta potential of FF-NC were 280.43 ± 8.21 nm and −19.64 ± 3.45 mV, and the electron microscopy results showed that FF-NC were nearly circular with no adhesion between particles. In addition, the drug loading, encapsulation efficiency, and dissolution of FF-NC did not change significantly during storage. The inhibition zone of FF-NC against Escherichia coli and Staphylococcus aureus was 21.37 ± 1.70 mm and 25.17 ± 2.47 mm, respectively. Compared with the FF, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of FF-NC are reduced, and the absorption rate constant (K a) and efficient permeability coefficient (P eff) of FF-NC in the three intestinal segments were increased by 1.28, 0.25, and 9.10 times and 0.59, 0.17, and 6.0 times, respectively. The results of tissue sections showed that FF-NC had little damage to the small intestinal. Nanocrystallisation technology is an effective method to increase the intestinal absorption and antibacterial activity of FF.

EFFECT OF NANONIZED CHRYSIN ON FEXOFENADINE PHARMACOKINETICS MEDIATED BY P-GLYCOPROTEIN IN RATS

Chrysin(CHR) is an abundant flavonoid in nature and has been found to possess P-glycoprotein (P-gp) inhibition activity in vitro, which may have the potential to alter bioavailability of P-gp substrates. The main objective of this study was to investigate the effect of nanonized chrysin (NCH) on the intestinal absorption and pharmacokinetics of P-gp probe substrate; fexofenadine in rats. NCH was prepared by antisolvent precipitation method and characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and in vitro dissolution testing. The influence of CHR and NCH on fexofenadine intestinal transport and permeability were evaluated by in vitro non-everted sac and in situ single pass intestinal perfusion (SPIP) studies. These findings were further confirmed by an in vivo pharmacokinetic study in which fexofenadine was administered (10 mg/kg, p.o) to CHR and NCH (50 mg/kg, p.o.) pretreated (10 days) rats and its plasma concentrations were determined by HPLC analysis. The intestinal transport and apparent permeability (Papp) of fexofenadine were significantly increased in duodenum, jejunum and ileum of CHR and NCH pretreated group as compared with the control. Similarly effective permeability (Peff) of fexofenadine was increased significantly in ileum of CHR and NCH pretreated group as compared with control. Cmax, AUC0-t and AUC0- ∞ of fexofenadine were found to be increased in CHR and NCH pretreated groups. Further, the CL/F and Vd/F of fexofenadine were significantly decreased. NCH enhances the oral bioavailability of fexofenadine by inhibition of P-gp mediated drug efflux during the intestinal absorption.

Comparision of the phenol red, gravimetric, and synthesized mPEG-PR methods for correcting water flux using the single-pass intestinal perfusion method

Phenol red and PEG-4000, the usual non-absorbable indicators, have non-negligible absorption problems in measuring water flux. mPEG-PR, combined phenol red with mPEG-4000, was first synthesized and could decrease absorption. However, its application has not been confirmed. The purpose of this study was to explore the applicability of mPEG-PR as a novel non-absorption indicator in the in situ single-pass intestinal perfusion (SPIP) experiment. Six model drugs (atenolol ranitidine, ibuprofen, ketoprofen, antipyrine, hydrochlorothiazide) were used to compare the accuracy of four measuring methods including phenol red, mPEG-PR, gravimetric, and non-corrected methods of correcting intestinal fluid transport. Moreover, we evaluated the correlations between the effective permeability coefficients (Peff) in rat and fraction dose absorbed (Fabs) in human, Peff in human, and apparent permeability coefficients (Papp) by the Ussing Chamber system using human tissue. Among these methods, mPEG-PR was the most reliable approach, which avoided the absorption of phenol red method and mucous shedding or water evaporation of gravimetric method. An excellent correlation was obtained between the Peff of rat and Fabs of human. Our results of this study indicated that mPEG-PR was a stable and accurate non-absorbable indicator to correct water flux in the in situ SPIP model, which could be developed to predict the human Fabs.

Pellets of phospholipids and d-glucose with improved intestinal absorption and oral bioavailability of salvianolic acid B

Salvianolic acid B (SAB) is a widely used cardioprotective agent, while its clinical application was limited by poor intestinal absorption and low oral bioavailability. In this study, SAB phospholipid (SP) complex was first prepared to improve the lipophilicity of SAB and then combined with d-glucose to further enhance intestinal absorption. Compared with free SAB, SP or the mixture of SAB and d-glucose, combination of SP and d-glucose showed higher intestinal absorption evidenced by increased effective permeation coefficient (Peff ) in the in situ single-pass intestinal perfusion (SPIP) assay. Subsequently, SP and d-glucose at mass ratio of 1:6, with the highest Peff of SAB, were chosen for the preparation of complexed pellets to improve oral absorption efficiency of SAB. As expected, the obtained pellets significantly enhanced oral bioavailability of SAB in the pharmacokinetic study characterized by increasing Cmax and AUC 0– t of SAB by 14.88-fold and 5.02-fold than free SAB, respectively. In conclusion, combination of d-glucose in SP pellets can effectively improve the intestinal absorption and oral bioavailability of SAB.

Intestinal absorption mechanism of rotundic acid: Involvement of P-gp and OATP2B1

Ethnopharmacological relevanceIlicis Rotundae Cortex (IRC), the dried barks of Ilex rotunda Thunb. (Aquifoliaceae), has been used for the prevention or treatment of colds, tonsillitis, dysentery, and gastrointestinal diseases in folk medicine due to its antibacterial and anti-inflammatory effects. However, there is no report about the intestinal absorption of major compounds that support traditional usage. Aim of studyConsidering the potential of rotundic acid (RA) – major biologically active pentacyclic triterpenes found in the IRC, this study was purposed to uncover the oral absorption mechanism of RA using in situ single-pass intestinal perfusion (SPIP) model, in vitro cell models (Caco-2, MDCKII-WT, MDCKII-MDR1, MDCKII-BCRP, and HEK293-OATP2B1 cells) and in vivo pharmacokinetics studies in rats. Materials and methodsThe molecular properties (solubility, lipophilicity, and chemical stability) and the effects of principal parameters (time, compound concentrations, pH, paracellular pathway, and the different intestinal segments) were analyzed by liquid chromatography-tandem mass spectrometry. The susceptibility of RA to various inhibitors, such as P-gp inhibitor verapamil, BCRP inhibitor Ko143, OATP 2B1 inhibitor rifampicin, and absorption enhancer EGTA were assessed. ResultsRA was a compound with low water solubility (12.89 μg/mL) and strong lipophilicity (LogP = 4.1). RA was considered stable in all media during the SPIP and transport studies. The SPIP and cell experiments showed RA was moderate absorbed in the intestines and exhibited time, concentration, pH, and segment-dependent permeability. In addition, results from the cell model, in situ SPIP model as well as the in vivo pharmacokinetics studies consistently showed that verapamil, rifampicin, and EGTA might have significant effect on the intestinal absorption of RA. ConclusionThe mechanisms of intestinal absorption of RA might involve multiple transport pathways, including passive diffusion, the participation of efflux (i.e., P-gp) and influx (i.e., OATP2B1) transporters, and paracellular pathways.

Rod-shaped nintedanib nanocrystals improved oral bioavailability through multiple intestinal absorption pathways

Nintedanib (BIBF) is a biopharmaceutical classification system II (BCS II) drug that has a good therapeutic effect for the treatment of nonsmall cell lung cancer; however, it shows poor oral bioavailability due to low dissolution and intestinal absorption. This study aims to fabricate rod-shaped nanocrystals to enhance oral bioavailability by improving the dissolution and absorption of BIBF in the intestine. By prescription screening, BIBF nanocrystals (BIBF-NCs) with a particle size of 325.30 ± 1.03 nm and zeta potential of 32.70 ± 1.24 mV were fabricated by an antisolvent precipitation-ultrasound approach with a stabilizer of sodium carboxyl methyl cellulose (CMC-Na). BIBF-NCs exhibited a rod-shaped morphology by transmission electron microscopy (TEM). The results of powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) showed that the crystal form of BIBF in BIBF-NCs was altered. The BIBF-NCs remarkably improved the saturation solubility and dissolution of BIBF compared with BIBF powder. According to the results of in situ single-pass intestinal perfusion (SPIP), BIBF-NCs showed improved absorption and membrane permeability, with Ka and Papp values in the jejunum of 0.21 ± 0.01 min−1 and (4.34 ± 0.11) × 10−4 cm/min, respectively. Further, the Ka and Papp values of BIBF-NCs were all reduced significantly after the addition of inhibitors colchicine, chlorpromazine and indomethacin, which demonstrated that BIBF-NCs could be absorbed by endocytosis mediated by caveolae and clathrin and micropinocytosis in the intestine. The cell evaluation results showed that BIBF-NCs could be taken up by macrophages and transported from Caco-2 monolayers. The in vivo pharmacokinetic results showed that the bioavailability of the BIBF-NCs was 2.51-fold higher than that of the BIBF solution (BIBF-Sol) after oral administration with a longer Tmax (4.50 ± 1.00 h vs. 2.60 ± 1.92 h). In summary, rod-shaped BIBF-NCs could significantly improve oral bioavailability through multiple intestinal absorption pathways.

Liquiritin enhancing intestinal absorption of paeoniflorin in in situ single-pass intestinal perfusion and in vitro Caco-2 cell monolayer absorption models

Background: Paeoniflorin and liquiritin are the primary active components of Shaoyao-Gancao-tang (SGT), a classical prescription for reducing pains. However, the interaction of paeoniflorin and liquiritin during intestinal absorption needs to be further studied. Objectives: In this study, we aimed to determine the interaction of paeoniflorin and liquiritin during intestinal absorption. Materials and Methods: The interaction between paeoniflorin and liquiritin (100 μM) was studied using in situ single-pass intestinal perfusion (SPIP) model use the whole small intestine and in vitro Caco-2 cell monolayer bidirectional transport model. Results: In situ SPIP research demonstrated that liquiritin significantly increased the Ka, Papp, absorption rate, and cumulative amount of paeoniflorin up to 7.97, 8.98, 7.07, and 10.71 folds, respectively, even higher than that of verapamil, a specific P-gp inhibitor, and control. Furthermore, 18 β-glycyrrhetinic acid (18 β-GA) markedly increased the Ka, Papp, absorption rate, and cumulative amount of paeoniflorin up to 3.30, 3.27, 3.42, and 4.04 folds, respectively. Bidirectional transport studies indicated that liquiritin and paeoniflorin could prompt the absorption of each other by increasing the Papp (AP-BL) of paeoniflorin and liquiritin from (3.83 ± 0.51) ×10−7 to (5.60 ± 0.51) ×10−7 cm/s and (3.86 ± 0.34) ×10−7 to (8.26 ± 0.51) ×10−7 cm/s, respectively. The 18 β-GA significantly prompted the Papp (AP-BL) of paeoniflorin to (5.54 ± 0.92) ×10−7 cm/s. Conclusion: Liquiritin and paeoniflorin increased the absorption of each other. This could provide essential reference to predict the oral bioavailability, the pharmacokinetics, and the clinical application of coadministration of liquiritin-and paeoniflorin-containing SGT and other herbal formulas.

Paeonol-loaded PLGA nanoparticles as an oral drug delivery system: Design, optimization and evaluation

Herein, we report a novel type of NPs by loading paeonol (Pae) into PLGA NPs, to enhance drug stability and oral bioavailability. The paeonol (Pae)-loaded polylactic-co-Gly-colic acid (PLGA) nanoparticles (Pae-PLGA-NPs) were prepared by nanoprecipitation method. The resultant NPs were in spherical shape with an average particle size around 237.7 ± 4.92 nm, and the PDI and zeta potential were 0.110 ± 0.01 and −25.33 ± 1.37 mV, respectively. The encapsulation efficiency (EE) and drug loading (DL) of the Pae-PLGA-NPs were 86.26 ± 1.12 and 12.74 ± 0.37% respectively. The in vitro drug release, in vivo pharmacokinetics and in situ single-pass intestinal perfusion (SPIPs) of Pae-PLGA-NPs was investigated. In vivo, the AUC(0-t), C max, MRT(0-t), and T1/2z of the Pae-PLGA-NPs group were 3.79-, 1.89-, 1.40- and 1.49-fold greater than those of the Pae suspension group, respectively. The in situ single-pass intestinal perfusion of NPs results showed the Ka values in the duodenum, jejunum, ileum and colon were 1.12-, 1.40-, 1.52- and 2.21-fold higher than those of Pae solution, respectively. Moreover, the Papp values of the ileum and colon were 1.27- and 1.31-fold higher than those of the solution group. Such findings suggested the Pae-PLGA-NPs can significantly improve the intestinal absorption characteristics, and have a beneficial effect on oral administration as a nanometer-sized carrier.

Panax quinquefolium saponin liposomes prepared by passive drug loading for improving intestinal absorption

Panax quinquefolium saponin (PQS) composed of 45% pseudo-ginsenoside F11 (PF11), is a natural mixture of sterol compounds obtained from the American ginseng plant, having numerous promising benefits for health. However, low solubility and permeability limit the development of PQS as a therapeutic agent for oral administration. In this study, PQS liposomes (PQS-Lips) were prepared by thin layer hydration, an in situ single-pass intestinal perfusion (SPIP) model was used to verify the improvement of membrane permeability of PQS-Lips. PQS-Lips had a high encapsulation efficiency (EE) of 65%∼70%, a particle size about 100.0 nm, and a zeta potential of −60 mV with regular spherical surface. FTIR and DSC showed the PQS in liposomes were amorphous, indicating that hydrogen bonds formed between one or several hydroxyl groups in PQS and C-O group at the phospholipid polar terminal. In addition, PQS-Lips showed sustained release in vitro than PQS at pH 1.2 and pH 6.8, and PQS-Lips had good stability in simulated gastric and intestinal fluid. Then, the absorption rate (K a) and effective permeability coefficient (P eff) of PQS-Lips in the whole small intestine were significantly higher than those in PQS solution (PQS-Sol), which proved that the PQS-Lips could significantly increase the membrane permeability of PQS and promote its absorption in the small intestine. From the experimental results, it could be known that liposome technology could effectively improve the absorption of PQS in the small intestine.

Formulation development of linagliptin solid lipid nanoparticles for oral bioavailability enhancement: role of P-gp inhibition.

Linagliptin (LGP), a novel anti-diabetic drug, is a DPP-4 inhibitor used in the treatment of type II diabetes. One of the major disadvantages of LGP is its low oral bioavailability (29.5%) due to first-pass metabolism and P-gp efflux. In an attempt to increase the oral bioavailability, LGP solid lipid nanoparticles (LGP-SLNs) were developed with poloxamer 188 and Tween 80 as P-gp inhibitors. LGP-SLNs were formulated using palmitic acid, poloxamer 188 and Tween 80 as lipid, surfactant and co-surfactant, respectively, by hot homogenization ultrasonication method and optimized using 32 full factorial designs. Particle size, entrapment efficiency (%EE) and drug release at 24h were evaluated as responses. An optimized batch of LGP-SLNs (L12) was evaluated for intestinal transport of LGP by conducting in situ single-pass intestinal perfusion (SPIP), everted gut sac and Caco-2 permeability study. The pharmacokinetic and pharmacodynamic evaluation of L12 was carried out in albino Wistar rats. The mean particle size, polydispersity index, zeta potential and %EE of L12 were found to be 225.96 ± 2.8nm, 0.180 ± 0.034, - 5.4 ± 1.07mV and 73.8 ± 1.73%, respectively. %CDR of 80.96 ± 3.13% was observed in 24h. The permeability values of LGP-SLNs in the absorptive direction were 1.82-, 1.76- and 1.74-folds higher than LGP-solution (LGP-SOL) in SPIP, everted gut sac and Caco-2 permeability studies, respectively. LGP-SLNs exhibited relative bioavailability of 300% and better reduction in glucose levels in comparison with LGP-SOL in rats. The enhanced oral bioavailability exhibited by LGP-SLNs bioavailability may be due to P-gp efflux inhibition and lymphatic targeting. Improved bioabsorption can cause reduction in dose, dose-related side effects and frequency of administration. Thus, LGP-SLNs can be considered promising carriers for oral delivery but clinical studies are required to confirm the proof of concept.Graphical abstract.

A Non-Lipolysis Nanoemulsion Improved Oral Bioavailability by Reducing the First-Pass Metabolism of Raloxifene, and Related Absorption Mechanisms Being Studied.

ObjectiveA non-lipolysis nanoemulsion (NNE) was designed to reduce the first-pass metabolism of raloxifene (RAL) by intestinal UDP-glucuronosyltransferases (UGTs) for increasing the oral absorption of RAL, coupled with in vitro and in vivo studies.MethodsIn vitro stability of NNE was evaluated by lipolysis and the UGT metabolism system. The oral bioavailability of NNE was studied in rats and pigs. Finally, the absorption mechanisms of NNE were investigated by in situ single-pass intestinal perfusion (SPIP) in rats, Madin-Darby canine kidney (MDCK) cells model, and lymphatic blocking model.ResultsThe pre-NNE consisted of isopropyl palmitate, linoleic acid, Cremophor RH40, and ethanol in a weight ratio of 3.33:1.67:3:2. Compared to lipolysis nanoemulsion of RAL (RAL-LNE), the RAL-NNE was more stable in in vitro gastrointestinal buffers, lipolysis, and UGT metabolism system (p < 0.05). The oral bioavailability was significantly improved by the NNE (203.30%) and the LNE (205.89%) relative to the suspension group in rats. However, 541.28% relative bioavailability was achieved in pigs after oral NNE intake compared to the suspension and had two-fold greater bioavailability than the LNE (p < 0.05). The RAL-NNE was mainly absorbed in the jejunum and had high permeability at the intestine of rats. The results of both SPIP and MDCK cell models demonstrated that the RAL-NNE was absorbed via endocytosis mediated by caveolin and clathrin. The other absorption route, the lymphatic transport (cycloheximide as blocking agent), was significantly improved by the NNE compared with the LNE (p < 0.05).ConclusionA NNE was successfully developed to reduce the first-pass metabolism of RAL in the intestine and enhance its lymphatic transport, thereby improving the oral bioavailability. Altogether, NNE is a promising carrier for the oral delivery of drugs with significant first-pass metabolism.

The Absorption Characteristics of Nonvolatile Components in a Water Extraction From Amomi fructus as Determined by In Situ Single-Pass Intestinal Perfusion and High-Performance Liquid Chromatography.

BackgroundAmomi fructus is a famous traditional Chinese medicine (TCM) that can exert beneficial effects during the treatment of gastrointestinal diseases and is used widely in China and other countries in Southeast Asia. However, the nonvolatile active ingredients that are present in the water extractions from A. fructus used to treat gastrointestinal diseases have yet to be elucidated. The goal of this study was to identify the nonvolatile active ingredients of A. fructus.MethodsWe used an in situ single-pass intestinal perfusion (SPIP) model to identify the active ingredients of A. fructus that play significant roles in gastrointestinal absorption. In addition, we developed a high-performance liquid chromatography (HPLC) method to identify key fractions in intestinal outflow perfusate.ResultsNineteen components were identified in a water extraction from A. fructus; these exhibited different absorption capabilities in different intestinal segments. Of these, six components were determined by the newly developed HPLC method: catechin, vanillic acid, epicatechin, polydatin, isoquercitrin, and quercitrin.ConclusionsThe current study aimed to identify the active ingredients present in water extractions prepared from A. fructus in a single-intestinal perfusate from rats. Our findings provide an experimental basis to explain the pharmacodynamic actions of A. fructus.

Purification and characterization of positive allosteric regulatory peptides of calcium sensing receptor (CaSR) from desalted duck egg white

HPLC-ESI-MS/MS, molecular docking simulation and in situ single-pass intestinal perfusion (SPIP) study were used to identify, select, and confirm the binding affinities between peptides identified from desalted duck egg white peptides (DPs) and calcium sensing receptor (CaSR), respectively. F3 fraction from DPs possessed superior calcium binding activity (P < 0.05), and 16 peptides enriched aromatic amino acids and other 33 peptides were identified. FAE, FNE, INSW, FDPE and NFE presented well binding affinities with CaSR in molecular docking. Additionally, SPIP results showed that NFE and INSW significantly reduced the increased PTH levels by 45.8% and 48.8%, respectively (P < 0.05), and increased calcium percent absorption, calcium absorption rate constant (Ka) and calcium effective permeability (Peff) (P < 0.05), as well as up-regulated mRNA levels of CaSR (P < 0.05). Moreover, NFE and INSW could interact with the VFT domain of CaSR, which exhibited the potential activities in regulation of CaSR.

Enhancement of the intestinal absorption of bortezomib by self-nanoemulsifying drug delivery system

Purpose: Intestinal drug absorption is one of the main factors that govern the fraction of oral dose absorbed (Fa) of drugs. It is reported that oral absorption of bortezomib (BTZ) can be restricted by its low intestinal permeability. In this study, we aimed to evaluate the impact of self-nanoemulsifying drug delivery systems (SNEDDS) on the intestinal absorption and Fa of BTZ.Methods: Intestinal permeability studies were conducted using in situ single-pass intestinal perfusion (SPIP) technique in rats. Human intestinal absorption (Peff (Human)) and Fa values of BTZ and BTZ-SNEDDS were predicted based on SPIP data.Results: Based on the obtained data, Peff (rat) values of (3.36 ± 0.5) × 10−5 and (8.9 ± 3) × 10−5 cm/s (mean ± SEM) were calculated for BTZ and BTZ-SNEDDS, respectively. Meanwhile, Peff (human) values of (7 × 10−5) and (68 × 10−5) cm/sec were predicted for BTZ and BTZ-SNEDDS, respectively. Besides, Fa (human) values of 72.5 and 97% were estimated for BTZ and BTZ-SNEDDS, respectively.Conclusions: According to the obtained data, it is concluded that SNEDDS can be considered as a promising drug delivery system to improve the intestinal absorption and Fa values of BTZ.

Repaglinide-loaded nanostructured lipid carriers with different particle sizes for improving oral absorption: preparation, characterization, pharmacokinetics, and in situ intestinal perfusion

Repaglinide-loaded nanostructured lipid carriers (REP-NLCs) with different particle sizes were successfully designed and prepared to investigate the permeation and absorption ability by in situ single-pass intestinal perfusion (SPIP) study and pharmacokinetics. Both of the formulations prepared by solvent diffusion method exhibited a spherical shape under transmission electron microscopy (TEM) and similar zeta potential value of –11 mV. The particles size, encapsulation efficiency (EE), drug loading (DL) of REP-NLCs-Small and REP-NLCs-Large size preparations were about 79 nm and 325 nm, 96.83% and 98.60%, 4.41% and 3.05%, respectively. Besides, both REP-NLCs showed good colloidal stability and had no burst release phenomenon compared with REP-Sol. SPIP demonstrated the improved membrane permeability for NLCs compared with REP-Sol, especially NLCs-Small size preparation. The bioavailability increased sequentially in REP-Sol, REP-NLCs-Large, and REP-NLCs-Small, and the difference between each other was statistical significant. Our investigations demonstrate that NLCs with small particles size of 50–100 nm, such as 79 nm, are able to enhance absorption performance of a poorly soluble repaglinide compared with large particles size, such as 325 nm, by significantly improving the absorption in jejunum, and colon of rats and thus well improving oral bioavailability.

Design, synthesis and performance evaluation of mPEG-PR: A novel non-absorbable marker

The aim of the present study was to develop a new marker for correcting water flux in the in situ single-pass intestinal perfusion (SPIP) model. The new marker was designed and synthesized based on the application of both polyethylene glycol-4000 (PEG-4000) and phenol red as non-absorbable markers. The new marker mPEG-PR was obtained by combining phenol red with polyethylene glycol monomethyl ether-4000 (mPEG-4000) and verified by nuclear magnetic resonance (NMR), ultraviolet (UV) spectra, gel permeability chromatograph (GPC) and differential scanning calorimetry (DSC). mPEG-PR fully took the advantages of phenol red and PEG including the low permeability and the simple measuring method which were assessed by the in vitro and the in situ models. In the everted gut sac (EGS) studies, the permeability of mPEG-PR was significantly reduced by nearly 4 times compared with phenol red, and the absorptive percentage of mPEG-PR was <0.1% in 105 min. In addition, the solution with verapamil or without Ca2+ could help improve the absorption of phenol red but did not influence the absorption of mPEG-PR. The results of isosorbide dinitrate as a model drug in the in situ SPIP study showed that both the mPEG-PR marker and the gravimetric method were useful for correcting water flux, which had smaller coefficients of variation than the phenol red marker and the non-corrected method. In conclusion, mPEG-PR could potentially be applied as an accurate and convenient marker for correcting water volume in the intestinal perfusion study.

Development and In Vivo Evaluation of Ziyuglycoside I\u2013Loaded Self-Microemulsifying Formulation for Activity of Increasing Leukocyte

Ziyuglycoside I (ZgI), a major effective ingredient of Sanguisorba officinalis L, has shown good activity in increasing leukocyte of myelosuppression mice. However, oral ZgI therapy has been deterred by poor bioavailability because of its low aqueous solubility and permeability. Our study was to develop ZgI-loaded self-microemulsifying drug delivery system (SMEDDS) and evaluate its intestinal absorption, and pharmacokinetic and pharmacodynamic activity for increasing leukocyte. The formulation was designed and optimized by measuring the equilibrium solubility of ZgI in different vehicles and the pseudoternary phase diagram. Further, morphology, particle size, stability, in vitro release, in situ single-pass intestinal perfusion (SPIP), in vivo activity, and in vivo pharmacokinetic (PK) of ZgI-SMEDDS were charactered or studied. Optimized formulations for in vitro dissolution were Obleique CC497, Tween-20, and Transcutol HP with a proportion of 0.25/0.45/0.30 via D-optimal mixture design. Results showed that the solubility of ZgI was enhanced up to 23.93 mg/g and its average particle size was 207.92 ± 2.13 nm. The release of ZgI had been greatly improved by the SMEDDS. In SPIP, the intestinal absorption of SMEDDS was much better than plain ZgI. In PK, we found the oral bioavailability of ZgI-SMEDDS was 6.94-fold higher absolute bioavailability (21.94 ± 4.67) % than ZgI (3.16 ± 0.89) %. The most important was that the mice WBC of ZgI-SMEDDS group was significantly higher than that of the ZgI group. Our study suggested that SMEDDS could increase the solubility of ZgI, which was beneficial to improve oral bioavailability and enhance biological activity.

Investigating Intestinal Permeability of Bortezomib Using a Validated HPLC-UV Method.

Bortezomib (BTZ), as a proteasome inhibitor, has been used for treatment of patients with relapsed/refractory multiple myeloma and mantle cell lymphoma. BTZ is available for intravenous injection or subcutaneous administration. In this study, for evaluating the potential of BTZ oral delivery, intestinal permeability of BTZ was determined using in situ single-pass intestinal perfusion (SPIP) technique and the perfused solutions were analyzed using a validated HPLC-UV method. The chromatographic separation was performed using a C18 column via isocratic mode at a flow rate of 0.5 mL/min at 270 nm. The mobile phase was a mixture of methanol/deionized water (50:50% v/v) with 0.1% glacial acetic acid. The results indicated that calibration curves were linear (r2 ˃0.99) in a concentration range of 1.65-5 µg/mL for BTZ and 8.33-25 µg/mL for phenol red. A limit of quantitation of 1.03 and 6.67 µg/mL was obtained for BTZ and phenol red, respectively. The recovery values were in the range of 96.5-105.4% for BTZ, and 88-99.2% for phenol red. The relative standard deviations (RSD) were ≤4.9% for BTZ and ≤7% for phenol red. Stability studies indicated that the working standard solution is stable over a period of 48 h at room temperature. Finally, an effective permeability (Peff) value of (3.36±0.5)×10-5 cm/sec (mean±SEM) was achieved for BTZ. Moreover, it was predicted that BTZ belongs to the biopharmaceutical class ІІІ.