Intestinal Perfusion Studies Research Articles

Development of a RP-HPLC method for simultaneous determination of atenolol, metoprolol tartrate and phenol red for in-situ rat intestinal perfusion studies

Single-pass intestinal perfusion (SPIP) method is a widely used experimental model to determine the intestinal permeability of drugs. These studies are performed in the presence of a reference standard (metoprolol, MT) and a zero permeability marker (phenol red, PR). Therefore, it is important to develop a validated method for simultaneous determination of the investigated compound along with MT and PR. The aim of this study was to develop a reversed phase high-performance liquid chromatography (RP-HPLC) method with UV-detection for the simultaneous determination of atenolol (ATN), MT, and PR in the perfusion medium used in SPIP experiments. Separation of compounds were performed using an InertSustain C18 (250 × 4.6 mm, 5 µm) HPLC column at 35 °C. The mobile phase was a mixture of acetonitrile and phosphate buffer (pH 7.0, 12.5 mM) in gradient elution, and was delivered at a flow rate of 1 mL/min. The acetonitrile ratio of the mobile phase increased linearly from 10 to 35 % over 15 min. The injection volume was 20 µL, and ATN, MT and PR were detected at 224 nm. The retention times under optimum HPLC conditions were 5.028 min, 12.401 min, and 13.507 min for ATN, MT and PR, respectively. The developed RP-HPLC method was validated for selectivity, specificity, calibration curve and range, accuracy and precision, carry-over effect, stability, reinjection reproducibility, recovery and robustness. The method was linear for ATN (0.76–50 μg/mL), MT (1.14–50 μg/mL), and PR (0.47–20 μg/mL) with determination coefficients of 0.9999, 0.9994 and 0.9998, respectively. The results obtained for all validation parameters of the developed RP-HPLC method met the required limits of the ICH M10 Guideline.

Enhancement of dissolution and oral bioavailability by adjusting microenvironment pH in crocetin ternary solid dispersions: Optimization, characterization, in vitro evaluation, and pharmacokinetics.

The most promising active ingredient of Crocus sativus L., crocetin (CCT), has been demonstrated to possess many biological activities. However, only a few studies have been conducted on CCT formulation, especially in oral formulation, mainly due to its insolubility in water, which limits its application for oral administration. This article reports an equilibrium saturation solubility and single-pass intestinal perfusion studies conducted to classify the biopharmaceutics classification system (BCS) of CCT. To enhance in vitro dissolution and in vivo oral bioavailability, ternary solid dispersions of CCT (CCT-SDs) with soluplus (SOL) as hydrophilic carrier and meglumine (MEG) as alkalizer were optimized using response surface methodology (RSM) with central composite design (CCD) experiments. Four different preparation methods were evaluated using the optimal formulation, including solvent evaporation, ball milling, spray drying, and freeze-drying. Prepared formulations were characterized by TG-DSC, FTIR, X-RPD, and SEM; the pharmacokinetic studies were performed in rats after oral administration. The cumulative dissolution rate of CCT-SDs containing SOL and MEG prepared by the ball milling method was 97.1% at 15min and remained at 95.6% at 480min, which was significantly higher than that of untreated CCT. The lower crystallinity, smaller particle size, and higher microenvironment pH (pHM) were observed in CCT-SDs prepared by the ball milling method. In vivo absorption of CCT-SDs (Cmax = 52.789 ± 12.441μg/mL and AUC0-12 = 191.748 ± 35.043μg/mL·h) was greater than untreated CCT (Cmax = 5.918 ± 1.388μg/mL and AUC0-12 = 44.309 ± 7.264μg/mL·h). In conclusion, the current study provides ternary solid dispersion formulation of CCT to increase the in vitro dissolution and in vivo bioavailability, which will benefit the commercial production and future clinical applications of CCT.

Towards Effective Antiviral Oral Therapy: Development of a Novel Self-Double Emulsifying Drug Delivery System for Improved Zanamivir Intestinal Permeability.

Self-double emulsifying drug delivery systems have the potential to enhance the intestinal permeability of drugs classified under the Biopharmaceutics Classification System (BCS) class III. One such example is the antiviral agent zanamivir, exhibiting suboptimal oral absorption (with a bioavailability range of 1-5%). To address this challenge, we have developed an innovative oral formulation for zanamivir: a self-double nanoemulsifying Winsor delivery system (SDNE-WDS) consisting of the microemulsion, which subsequently yields final double nanoemulsion (W1/O/W2) upon interaction with water. Two distinct formulations were prepared: SDNE-WDS1, classified as a W/O microemulsion, and SDNE-WDS2, discovered to be a bicontinuous microemulsion. The inner microemulsions displayed a consistent radius of gyration, with an average size of 35.1 ± 2.1 nm. Following self-emulsification, the resultant zanamivir-loaded nanoemulsion droplets for zSDNE-WDS1 and zSDNE-WDS2 measured 542.1 ± 36.1 and 174.4 ± 3.4 nm, respectively. Both types of emulsions demonstrated the ability to enhance the transport of zanamivir across a parallel artificial membrane. Additionally, in situ rat intestinal perfusion studies involving drug-loaded SDNE-WDSs revealed a significantly increased permeability of zanamivir through the small intestinal wall. Notably, both SDNE-WDS formulations exhibited effective permeability (Peff) values that were 3.5-5.5-fold higher than those of the low/high permeability boundary marker metoprolol. This research emphasizes the success of SDNE-WDSs in overcoming intestinal permeability barriers and enabling the effective oral administration of zanamivir. These findings hold promise for advancing the development of efficacious oral administration of BCS class III drugs.

A Novel Oral Drugs Delivery System for Borneol Based on HiCap®100 and Maltodextrin: Preparation, Characterization, and the Investigation as an Intestinal Absorption Enhancer.

The objective of this study was to create a new method for delivering oral borneol (BN) drug that would improve stability. This was accomplished through microencapsulation using HiCap®100 and maltodextrin (MD), resulting in HiCap®100/MD/BN microcapsules (MCs). The HiCap®100/MD/BN MCs were evaluated in terms of encapsulation efficiency (EE%), drug loading (DL%), morphological observations, particle size distribution, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermal analysis, drug degradation rate studies, and in vitro release behavior. The effect of MCs on intestinal permeability in a rat model was assessed using the model drug "florfenicol" (FF) in single-pass intestinal perfusion (SPIP) study. The relationship between MCs and P-glycoprotein (P-gp) was further investigated in comparison with verapamil (Ver). The irritation of MCs was assessed by histological analysis. The MCs in a spherical structure with micron-scale dimensions were obtained. The EE% and DL% were (86.71 ± 0.96)% and (6.03 ± 0.32)%, respectively. MCs played a significantly protective role in drug degradation rate studies. In vitro release studies indicated that the release behavior of MCs was significantly better than BN at the three-release media, and the cumulative release rate exceeded 90% in 15 min. The SPIP studies showed that MCs significantly enhanced the absorption of FF in rats. Compared with Ver, MCs were not promoted by a single inhibition of P-gp. Hematoxylin-eosin (HE)-stained images showed that MCs had no obvious irritation and toxic effects on the intestines of rats. Thus, the preparation of HiCap®100/MD/BN MCs improves the stability of BN, which has certain scientific value for the development and application of BN, and provides unique perspectives for future BN-related researches.

Lumefantrine solid dispersions with piperine for the enhancement of solubility, bioavailability and anti-parasite activity

Crystallinity and P-glycoprotein (P-gp) mediated efflux of drugs with low aqueous solubility collaboratively contributes to erratic absorption resulting in low/variable bioavailability. Herein, the amorphous solid dispersions (SD) of lumefantrine (LUMF) containing piperine (PIP), a P-gp and CYP3A4 inhibitor, were formulated with Soluplus (Sol), Klucel (Klu) and Lutrol F68 (Lut), polymeric carriers, to improve solubility and bioavailability of LUMF following oral administration. The LUMF-PIP-SD prepared with Sol exhibited higher aqueous solubility of LUMF in concentration dependent manner and LUMF-PIP-Sol demonstrating maximum aqueous LUMF solubility were characterized by DSC, FTIR and XRD. The DSC thermogram and XRD diffractogram of LUMF-PIP-SD confirmed the loss of crystallinity of LUMF ensuing improved dissolution while possible interaction of LUMF with PIP and /or Sol was evident in FTIR spectrum. DSC and dissolution studies confirmed the stability for LUMF-PIP-Sol SD stored for 90 days under stressed conditions of humidity and temperature. An in situ single-pass intestinal perfusion study in rats indicated 2.2-fold increase in intestinal permeation of LUMF co-administered with PIP. Improved bioavailability of LUMF was evidenced by increased AUC0-∞ and Cmax for LUMF in SD compared to alone LUMF or LUMF with PIP. Peter’s four-day suppressive test indicated improved antimalarial activity for LUMF-PIP-Sol SD. Overall, the data suggest that the SD of LUMF incorporated with P-gp inhibitor PIP, improves the bioavailability as well as antimalarial efficacy of LUMF.

Study on the Absorption of Arsenic Species in Realgar Based on the Form and Valence.

At present, several experiments have been carried out to study the changes in total arsenic content of realgar and its prescription, but few researches on its form and valence. We evaluated the change in arsenic species concentration in realgar from the perspective of absorption by using an in vitro dissolution study, an in vivo unidirectional intestinal perfusion study, transmembrane transport in Caco-2 cells, and a pharmacokinetic study in rats. In the gastrointestinal tract, arsenic species are mainly present inorganic forms of AsIII and AsV. The cumulative dissolution rates of soluble arsenic in 4 h artificial gastric fluid and 8 h artificial intestinal fluid were 21.99% and 59.20%, respectively. The Papp values of soluble arsenic in realgar in the duodenum, jejunum, and ileum of rats were 5.4 × 10−3, 6.1 × 10−3 and 5.8 × 10−3 cm/min, respectively. In the process of small intestine perfusion, the AsIII of realgar was partially converted into AsV in the duodenum and jejunum. As the transport time increased, the transmembrane transport rate and Papp value of soluble arsenic in realgar were increased in Caco-2 cells, and it also suggested that arsenic species may be passively transported across the Caco-2 cell monolayer. The Cmax and AUC (0-24) of AsIII, AsV, and DMA in plasma of realgar were 41.26 ng L−1/343.977 ng h mL−1, 21.626 ng L−1/47.310 ng h mL−1, and 2.372 ng L−1/30.429 ng h mL−1, respectively. Tmax and MRT (0-∞) of AsIII, AsV, and DMA were 2.571 h/9.649 h, 0.393 h/2.790 h, and 3.143 h/23.145 h, respectively. It is hoped to provide a basis for clarifying the arsenic species in realgar.

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.

The Role of Paracellular Transport in the Intestinal Absorption and Biopharmaceutical Characterization of Minoxidil.

The purpose of this study was to evaluate mechanisms behind the intestinal permeability of minoxidil, with special emphasis on paracellular transport, and elucidate the suitability of minoxidil to be a reference drug for Biopharmaceutics Classification System (BCS). The permeability of minoxidil (vs. metoprolol) was evaluated in-silico, in-vitro using both the PAMPA assay and across Caco-2 cell monolayers, as well as in-vivo in rats throughout the entire intestine. The permeability was studied in conditions that represent the different segments of the small intestine: upper jejunum (pH 6.5), mid small intestine (pH 7.0), distal ileum (pH 7.5), and colon (pH 6.5). Since we aimed to investigate the paracellular transport of minoxidil, we have also examined its permeability in the presence of quercetin (250 µM), which closes the tight junctions, and sodium decanoate (10 mM), which opens the tight junctions. While metoprolol demonstrated segmental-dependent rat and PAMPA permeability, with higher permeability in higher pH regions, the permeability of minoxidil was pH-independent. Minoxidil PAMPA permeability was significantly lower than its rat permeability, indicating a potential significant role of the paracellular route. In rat intestinal perfusion studies, and across Caco-2 monolayers, tight junction modifiers significantly affected minoxidil permeability; while the presence of quercetin caused decreased permeability, the presence of sodium decanoate caused an increase in minoxidil permeability. In accordance with these in-vitro and in-vivo results, in-silico simulations indicated that approximatelly 15% of minoxidil dose is absorbed paracellularly, mainly in the proximal parts of the intestine. The results of this study indicate that paracellular transport plays a significant role in the intestinal permeability of minoxidil following oral administration. Since this permeation route may lead to higher variability in comparison to transcellular, these findings diminish the suitability of minoxidil to serve as the low/high BSC permeability class benchmark.

Protective Effects of Melatonin and Misoprostol against Experimentally Induced Increases in Intestinal Permeability in Rats.

Intestinal mucosal barrier dysfunction caused by disease and/or chemotherapy lacks an effective treatment, which highlights a strong medical need. Our group has previously demonstrated the potential of melatonin and misoprostol to treat increases in intestinal mucosal permeability induced by 15-min luminal exposure to a surfactant, sodium dodecyl sulfate (SDS). However, it is not known which luminal melatonin and misoprostol concentrations are effective, and whether they are effective for a longer SDS exposure time. The objective of this single-pass intestinal perfusion study in rats was to investigate the concentration-dependent effect of melatonin and misoprostol on an increase in intestinal permeability induced by 60-min luminal SDS exposure. The cytoprotective effect was investigated by evaluating the intestinal clearance of 51Cr-labeled EDTA in response to luminal SDS as well as a histological evaluation of the exposed tissue. Melatonin at both 10 and 100 µM reduced SDS-induced increase in permeability by 50%. Misoprostol at 1 and 10 µM reduced the permeability by 50 and 75%, respectively. Combination of the two drugs at their respective highest concentrations had no additive protective effect. These in vivo results support further investigations of melatonin and misoprostol for oral treatments of a dysfunctional intestinal barrier.

Comparative pharmacokinetics, intestinal absorption and urinary excretion of six alkaloids from herb pair Phellodendri Chinensis cortex-Atractylodis Rhizoma.

Phellodendri Chinensis Cortex (PCC) and Atractylodis Rhizoma (AR) are frequently used as herb pair to treat eczema and gout owing to their synergistic effects. Alkaloids are the major ingredients from PCC and the effect of their combination on the in vivo processing of alkaloids remains unclear. In this study, a simple and reliable UPLC-MS/MS method for simultaneous determination of six alkaloids in rat plasma was developed. This method was applied to a comparative pharmacokinetic study between PCC and PCC-AR in rats. Effect of AR on absorption of alkaloids was investigated by a single-pass intestinal perfusion study. The effect of AR on urinary excretion of alkaloids was studied. Pharmacokinetic studies showed that the values of rea under the concentration-time curve of phellodendrine, magnoflorine and palmatine were greater in the PCC-AR group than in the PCC group. The intestinal absorptive parameters absorption rate constant and effective permeability of phellodendrine and jatrorrhizine in PCC-AR groups were higher than those in the PCC group. Urinary excretion studies revealed that the excreted amount of alkaloids in the PCC-AR group was lower than that in the PCC group. The results revealed that the combination of PCC and AR improves intestinal absorption of alkaloids and reduces their urinary excretion, which enhances their systemic exposure. This study may explain the synergetic effects of PCC and AR in clinical applications.

Melatonin-Activated Receptor Signaling Pathways Mediate Protective Effects on Surfactant-Induced Increase in Jejunal Mucosal Permeability in Rats.

A well-functional intestinal mucosal barrier can be compromised as a result of various diseases, chemotherapy, radiation, and chemical exposures including surfactants. Currently, there are no approved drugs targeting a dysfunctional intestinal barrier, which emphasizes a significant medical need. One candidate drug reported to regulate intestinal mucosal permeability is melatonin. However, it is still unclear if its effect is primarily receptor mediated or antioxidative, and if it is associated with enteric neural pathways. The aim of this rat intestinal perfusion study was to investigate the mechanisms of melatonin and nicotinic acetylcholine receptors on the increase in intestinal mucosal clearance of 51Cr-labeled ethylenediaminetetraacetate induced by 15 min luminal exposure to the anionic surfactant, sodium dodecyl sulfate. Our results show that melatonin abolished the surfactant-induced increase in intestinal permeability and that this effect was inhibited by luzindole, a melatonin receptor antagonist. In addition, mecamylamine, an antagonist of nicotinic acetylcholine receptors, reduced the surfactant-induced increase in mucosal permeability, using a signaling pathway not influenced by melatonin receptor activation. In conclusion, our results support melatonin as a potentially potent candidate for the oral treatment of a compromised intestinal mucosal barrier, and that its protective effect is primarily receptor-mediated.

Pueraria-flavones-loaded bile salt liposomes with improved intestinal absorption and oral bioavailability: in vitro and in vivo evaluation

Pueraria flavone (PF), the main component of Pueraria lobata, is a traditional Chinese medicine used for the treatment of cardiovascular and cerebrovascular diseases; however, it exhibits low oral bioavailability because of its poor membrane permeability. In this study, PF-loaded sodium deoxycholate-decorated liposomes (SDC-Lips) were prepared using the reverse-phase evaporation method and optimised using the Box–Behnken design method. The morphology, particle size, zeta potential, and entrapment efficiency of these PF-loaded SDC-Lips were evaluated. The release behaviours of PF-loaded SDC-Lips in simulated gastric and intestinal fluids were consistent with the Weibull kinetic model. In-situ intestinal perfusion studies showed that the absorption characteristics of free PF in rats were mainly passive diffusion and partly active transport, and the duodenum was the main absorption site. After encapsulated with SDC-Lips, the absorption of PF increased significantly. The in-vivo pharmacokinetic parameters of area under the plasma concentration-time curve (AUC)(0→12h) and AUC(0→ꝏ) of PF-loaded SDC-Lips after intragastric administration were 1.34-fold and 1.543-fold, respectively. Overall, the PF-loaded SDC-Lips improved the oral absorption of PF by increasing its solubility and might be considered a promising formulation strategy for prolonging the biological activity time of PF.

Improved intestinal absorption and oral bioavailability of astaxanthin using poly (ethylene glycol)-graft-chitosan nanoparticles: preparation, in vitro evaluation, and pharmacokinetics in rats.

Astaxanthin (ASTA) is a kind of food-derived active ingredient (FDAI) with antioxidant and antidiabetic functions. It is nontoxic but its poor solubility and low bioavailability hinder its application in the food industry. In this study, a novel carrier, polyethylene glycol-grafted chitosan (PEG-g-CS) was applied to enhance the bioavailability of astaxanthin. It encapsulated astaxanthin completely by solvent evaporation to manufacture astaxanthin using poly (ethylene glycol)-graft-chitosan nanoparticles (ASTA-PEG-g-CS) nanoparticles to improve absorption. The ASTA-PEG-g-CS nanoparticles were spherical, with a particle size below 200 nm and a ζ potential of about -26 mV. Polyethylene glycol-grafted chitosan can encapsulate astaxanthin well, and the encapsulated astaxanthin was released rapidly - in 15 min in an in vitro release study. In a rat single-pass intestinal perfusion study, a low concentration of ASTA-PEG-g-CS nanoparticle (0.2μg mL-1 ) was better absorbed in the intestine. In particular, the jejunum could absorb most astaxanthin without a change in the concentration. An in vivo release study also demonstrated that ASTA-PEG-g-CS nanoparticles enhanced oral bioavailability significantly. This novel carrier, PEG-g-CS, provided a simple way to encapsulate food, which improved the bioavailability of hydrophobic ingredients. © 2021 Society of Chemical Industry.

Effect of self-assembled nanoparticles from Shaoyao Gancao Decoction on release and absorption of main components of Baishao

To study the effect of self-assembled nanoparticles from Shaoyao Gancao Decoction(SGD-SAN) on the encapsulation, in vitro release and intestinal absorption of the main components of Baishao. Particle size analysis and morphological observation were used to verify the formation of SGD-SAN in the decoction. The entrapment efficiency(EE) of SGD-SAN on the main components of Baishao was determined by ultrafiltration centrifugation. The dialysis bag method was used to study the in vitro release of the main components of Baishao with pH 6.8 phosphate buffer solution as the release media. Single-pass intestinal perfusion study was performed to investigate the effect of SGD-SAN on the absorption of the main components of Baishao. The results showed that there were nanoparticles in the SGD, and the particle sizes and PDI of SGD-SAN were about 200 nm and 0.38, respectively. SGD-SAN was irregularly spherical under transmission electron microscope(TEM). The EEs of albiflorin, paeoniflorin and benzoylpaeoniflorin in SGD-SAN were 33.78%±1.03%,33.61%±0.90%,88.53%±0.58%, respectively. The release characteristics of albiflorin, paeoniflorin and benzoylpaeoniflorin from SGD-SAN showed a slow-release effect on pH 6.8 phosphate buffer solution media. SGD-SAN could significantly enhance the absorption of albiflorin, paeoniflorin and benzoylpaeoniflorin in the ileum. The results of this study indicated that SAN could be formed during the mixed decoction of Baishao and Gancao, and SGD-SAN could encapsulate the components of Baishao, with a certain slow-release effect, and the formation of SAN facilitated the absorption of drugs in the ileum.

Eremantholide C from aerial parts of Lychnophora trichocarpha, as drug candidate: fraction absorbed prediction in humans and BCS permeability class determination.

Lychnophora trichocarpha (Spreng.) Spreng. ex Sch.Bip has been used in folk medicine to treat pain, inflammation, rheumatism and bruises. Eremantholide C, a sesquiterpene lactone, is one of the substances responsible for the anti-inflammatory and anti-hyperuricemic effects of L. trichocarpha. Considering the potential to become a drug for the treatment of inflammation and gouty arthritis, this study evaluated the permeability of eremantholide C using in situ intestinal perfusion in rats. From the permeability data, it was possible to predict the fraction absorbed of eremantholide C in humans and elucidate its oral absorption process. In situ intestinal perfusion studies were performed in the complete small intestine of rats using different concentrations of eremantholide C: 960μg/ml, 96μg/ml and 9.6μg/ml (with and without sodium azide), in order to verify the lack of dependence on the measured permeability as a function of the substance concentration in the perfusion solutions. Eremantholide C showed Peff values, in rats, greater than 5 × 10-5cm/s and fraction absorbed predicted for humans greater than 85%. These results indicated the high permeability for eremantholide C. Moreover, its permeation process occurs only by passive route, because there were no statistically significant differences between the Peff values for eremantholide C. The high permeability, in addition to the low solubility, indicated that eremantholide C is a biologically active substance BCS class II. The pharmacological activities, low toxicity and biopharmaceutics parameters demonstrate that eremantholide C has the necessary requirements for the development of a drug product, to be administered orally, with action on inflammation, hyperuricemia and gout.

Nanoparticulate tablet dosage form of lisofylline-linoleic acid conjugate for type 1 diabetes: in situ single-pass intestinal perfusion (SPIP) studies and pharmacokinetics in rat.

Lisofylline (LSF) is an anti-inflammatory molecule with high aqueous solubility and rapid metabolic interconversion to its parent drug, pentoxifylline (PTX) resulting in very poor pharmacokinetic (PK) parameters, necessitating high dose and dosing frequency. In the present study, we resolved the physicochemical and pharmacokinetic limitations associated with LSF and designed its oral dosage form as a tablet for effective treatment in type 1 diabetes (T1D). Self-assembling polymeric micelles of LSF (lisofylline-linoleic acid polymeric micelles (LSF-LA PLM)) were optimized for scale-up (6 g batch size) and lyophilized followed by compression into tablets. Powder blend and tablets were evaluated as per USP. LSF-LA PLM tablet so formed was evaluated for in vitro release in simulated biological fluids (with enzymes) and for cell viability in MIN-6 cells. LSF-LA PLM in tablet formulation was further evaluated for intestinal permeability (in situ) along with LSF and LSF-LA self-assembled micelles (SM) as controls in a rat model using single-pass intestinal perfusion (SPIP) study. SPIP studies revealed 1.8-fold higher oral absorption of LSF-LA from LSF-LA PLM as compared to LSF-LA SM and ~5.9-fold higher than LSF (alone) solution. Pharmacokinetic studies of LSF-LA PLM tablet showed greater Cmax than LSF, LSF-LA, and LSF-LA PLM. Designed facile LSF-LA PLM tablet dosage form has potential for an immediate decrease in the postprandial glucose levels in patients of T1D.

Development and validation of RP-HPLC method for simultaneous determination of lamivudine, stavudine, and zidovudine in perfusate samples: Application to the Single-Pass Intestinal Perfusion (SPIP) studies

A reversed-phase high performance liquid chromatography (RP-HPLC) method with ultraviolet detection was developed and validated for the simultaneous quantification of antiretroviral drugs lamivudine (3TC), stavudine (d4T), and zidovudine (AZT) in perfusate samples obtained from the Single-Pass Intestinal Perfusion studies. The chromatographic analysis was performed using a Gemini C18 column and didanosine as internal standard (IS). The following parameters were considered for the validation procedure: system suitability, accuracy, precision, linearity and selectivity. The limits of detection were 0.32 µg/mL for 3TC, 0.11 µg/mL for d4T and 0.45 µg/mL for AZT and the limits of quantification were 1.06 µg/mL for 3TC, 0.38 µg/mL for d4T and 1.51 µg/mL for AZT. Repeatability and intermediate precision ranged from 1.05 to 1.31 and 1.50 to 1.87, respectively, and are expressed as percent of relative standard deviation (RSD). Based on these results, the developed and validated RP-HPLC method can be used for simultaneous determination of 3TC, d4T, and AZT in perfusate samples. Furthermore, this method is simple and adequate for measurements of the antiretroviral drugs in the same sample, since those compounds are mostly co-administered. Besides, this work can be used as an initial base for the development of similar methods in the same conditions presented in our study.

Glycyrrhizic acid-based self-assembled micelles for improving oral bioavailability of paeoniflorin

Background Paeoniflorin (Pae), a water-soluble monoterpene glucoside, has high potential clinical value in autoimmune and inflammatory diseases. However, the extremely low oral bioavailability of Pae (approximately 3%–4%) limits its formulation development and clinical application. This study aimed to develop micelles using the glycyrrhizic acid (GL) as the carrier to improve the oral absorption of Pae. Methods Pae-loaded GL micelles were prepared by the ultrasonic dispersion method and its formulation was optimized by single-factor tests. Characterizations of Pae-loaded GL micelles including particle size, zeta potential, entrapment efficiency (EE), drug loading (DL), morphology, and drug release in vitro were carried out. The single-pass intestinal perfusion and pharmacokinetic studies of Pae-loaded GL micelles were also evaluated in rats and compared with Pae solution and the mixed solution of Pae and GL. Results The optimized Pae-loaded GL micelles had EE of (42.21 ± 0.89)%, particle size of (58.89 ± 4.24) nm with PDI of (0.194 ± 0.010), zeta potential of (−24.40 ± 1.90) mV. Pae-loaded GL micelles showed a nearly spherical shape under TEM. Drug release of micelles demonstrated a delayed drug release compared to Pae solution. The single-pass intestinal perfusion study showed a significantly higher permeability of Pae in duodenum (p < 0.05), jejunum (p < 0.05), ileum (p < 0.01) and colon (p < 0.01) intestine after perfusion of Pae-loaded GL micelles as compared to Pae solution. The in vivo pharmacokinetics demonstrated that the Cmax and AUC0–t values of Pae-loaded GL micelles were approximately 2.18- and 3.64-fold superior than the Pae solution. Conclusion These results suggested GL could be a potential carrier for the oral delivery of Pae.

Prevention of Rat Intestinal Injury with a Drug Combination of Melatonin and Misoprostol.

A healthy intestinal barrier prevents uptake of allergens and toxins, whereas intestinal permeability increases following chemotherapy and in many gastrointestinal and systemic diseases and disorders. Currently, there are no approved drugs that target and repair the intestinal epithelial barrier while there is a medical need for such treatment in gastrointestinal and related conditions. The objective of this single-pass intestinal perfusion study in rats was to investigate the preventive cytoprotective effect of three mucosal protective drugs—melatonin, misoprostol, and teduglutide—with different mechanisms of action on an acute jejunal injury induced by exposing the intestine for 15 min to the anionic surfactant, sodium dodecyl sulfate (SDS). The effect was evaluated by monitoring intestinal clearance of 51Cr-labeled ethylenediaminetetraacetate and intestinal histology before, during, and after luminal exposure to SDS. Our results showed that separate pharmacological pretreatments with luminal misoprostol and melatonin reduced acute SDS-induced intestinal injury by 47% and 58%, respectively, while their use in combination abolished this injury. This data supports further development of drug combinations for oral treatments of conditions and disorders related to a dysregulated or compromised mucosal epithelial barrier.

Type 2 diabetes mellitus decreases systemic exposure of clopidogrel active metabolite through upregulation of P-glycoprotein in rats

Patients with diabetic mellitus tend to have a poor response to clopidogrel (Clop) due to reduced generation of active metabolite (Clop-AM). However, the underlying mechanism is not elucidated. A type 2 diabetic mellitus (T2DM) rat model was established by combining high-fat diet feeding and low-dose streptozotocin (STZ) injection. The reduced Clop-AM exposure was observed in T2DM rats after oral administration of Clop. However, in vitro liver microsomes incubated with Clop exhibited increased Clop-AM levels in T2DM rats due to a significant decrease in carboxylesterase (CES)1 expression and activity and a significant increase in the expression or activity of CYP1A2 and CYP3A. Interestingly, different from oral administration, the significantly increased Cmax of Clop-AM was observed in T2DM rats after intravenous injection, with no difference in AUC0-t and t1/2 values between the two strains. Meanwhile, in situ single -pass intestinal perfusion study showed lower absorption rate constant (Ka) and effective apparent permeability values (Peff) of Clop in T2DM rats than in control rats. It is explained by the increased expression or function of P-glycoprotein (P-gp) and pregnane X receptor (PXR) in duodenum and jejunum of T2DM rats. Moreover, the decreased Clop-AM level in T2DM rats was eliminated by the pretreatment of cyclosporin A, a P-gp inhibitor. It suggests that intestinal absorption, not hepatic metabolism is responsible for the reduced Clop-AM exposure in T2DM rats. P-gp might be the key factor causing the reduction of Clop absorption, consequently making less Clop available for Clop-AM formation.