Intestinal transport of sophocarpine across the Caco-2 cell monolayer model and quantification by LC/MS

Studies on absorption mechanism and pharmacokinetic properties of albendazole-bile acid conjugate: In vivo and in vitro

PURPOSE

To improve the oral bioavailability of albendazole (ABZ), a series of albendazole-bile acid conjugates (ABCs) were synthesized. ABC's transmembrane transport mechanism and in vivo pharmacokinetic properties were preliminarily studied.

METHODS

The transmembrane transport mechanism of ABCs was studied using the Caco-2 monolayer cell model and intestinal perfusion model. The concentration of ABCs and ABZ were evaluated using High-Performance Liquid Chromatography (HPLC) and HPLC-Mass Spectrometry (HPLC-MS/MS).

RESULTS

Compared to ABZ, better permeability was observed for different types and concentrations of ABCs using the Caco-2 monolayer cell model, with ABC-C8 showing the highest permeability. The transmembrane transport of ABCs was affected by ASBT inhibitors, indicating an ASBT-mediated active transport mechanism. Additionally, introducing cholic acid resulted in ABZ no longer being a substrate for P-gp, MRP2, and BCRP, effectively reversing ABZ efflux. In vivo unidirectional intestinal perfusion results in rats showed that ABCs altered the absorption site of ABZ from the jejunum to the ileum. The absorption efficiency of ABCs in each intestinal segment was higher than that of ABZ, and the transmembrane transport efficiency decreased with increasing concentrations of ASBT inhibitors. This further confirmed the presence of both passive diffusion and ASBT-mediated active transport mechanisms in the transport of ABCs. The solubility of ABCs in gastric juice and pharmacokinetics in rats showed that ABZ-C4 exhibited enhanced solubility. Moreover, ABCs significantly increased oral bioavailability compared to ABZ, with ABC-C4 showing an approximately 31-fold increase in bioavailability.

CONCLUSION

The transmembrane transport mechanism of ABCs involves a combination of ASBT-mediated active transport and passive diffusion. Moreover, the incorporation of BAs successfully reverses the efflux of ABZ by efflux proteins. Among the synthesized conjugates, ABC-C4 demonstrated superior dissolution behavior both in vitro and in vivo.

Effects of D-α-tocopherol polyethylene glycol succinate-emulsified poly(lactic-co-glycolic acid) nanoparticles on the absorption, pharmacokinetics, and pharmacodynamics of salinomycin sodium

Although salinomycin sodium (SS) has shown in-vitro potential to inhibit cancer stem cell growth and development, its low water solubility makes it a poor candidate as an oral chemotherapeutic agent. To improve the bioavailability of SS, SS was encapsulated here using D-α-tocopherol polyethylene glycol succinate (TPGS)-emulsified poly(lactic-co-glycolic acid) (PLGA) nanoparticles and compared with its parent SS in terms of absorption, pharmacokinetics, and efficacy in suppressing nasopharyngeal carcinomas stem cells. The pharmacokinetics of SS and salinomycin sodium-loaded D-α-tocopherol polyethylene glycol succinate-emulsified poly(lactic-co-glycolic acid) nanoparticles (SLN) prepared by nanoprecipitation were analyzed in-vivo by timed-interval blood sampling and oral administration of SS and SLN to rats. Sensitive liquid chromatography-mass spectrometry (LC-MS) was developed to quantify plasma drug concentrations. SS and SLN transport in Caco-2 cells was also investigated. The therapeutic efficacy of SS and SLN against cancer stem cells was determined by orally administering the drugs to mice bearing CNE1 and CNE2 nasopharyngeal carcinoma xenografts and then evaluating CD133 cell proportions and tumorsphere formation. The in-vivo trial with rats showed that the Cmax, AUC(0-t), and Tmax for orally administered SLN were all significantly higher than those for SS (P<0.05). These findings were corroborated by a Caco-2 cell Transwell assay showing that relative SLN absorption was greater than that of SS on the basis of their apparent permeability coefficients (Papp). Significantly, therapeutic SLN efficacy against nasopharyngeal carcinoma stem cells was superior to that of SS. TPGS-emulsified PLGA nanoparticles effectively increase SS solubility and bioavailability. SLN is, therefore, promising as an oral chemotherapeutic agent against cancer stem cells.

Investigating the Bioaccessibility and Bioavailability of Cadmium in a Cooked Rice Food Matrix by Using an 11-Day Rapid Caco-2/HT-29 Co-culture Cell Model Combined with an In Vitro Digestion Model

Investigating the bioaccessibility and bioavailability of Cd based on real contaminated cooked rice matrixes helps establish an accurate risk assessment method and effectively reduce the digestion and absorption of Cd. An 11-day in vitro rapid Caco-2/HT-29 co-culture cell model was used to establish and evaluate the simulation of the absorption and transport of Cd in the small intestine with a 70:30 Caco-2/HT-29 co-culture ratio and 1.0 mmol L^-1 butyric acid as a differentiation inducer. The bioaccessibility and bioavailability of Cd in cooked rice were studied using the cell model combined with an in vitro digestion model. The bioaccessibility of Cd of each of the three cooked rice samples was significantly higher in the gastric phase (59.04-80.23%) than in the gastrointestinal phase (37.14-52.93%). Despite the extension of the digestion time of the gastrointestinal phase, no significant difference was found among the time points. Results demonstrated that the amount of undigested residue, not the level of Cd contamination, significantly contributed to the bioaccessibility of Cd, which was affected by pH or ion. The absorption rate of Cd (25.08% ± 3.05%) was greater than the values obtained using the pure Caco-2 cell models. The bioavailability of Cd (8.29% ± 1.95%) was almost similar to that of Zn²⁺ (6.66% ± 1.41%) in the cooked rice matrix, indicating that the intestinal epithelium expressed a strong absorptive capacity of Cd during the absorption of essential metallic elements. The 11-day rapid Caco-2/HT-29 co-culture cell model combined with the in vitro digestion model was an efficient tool for studying the bioaccessibility and bioavailability of Cd or other substances in a food matrix to further investigate mechanistic steps and screen a broad set of food matrix factors.

In vitro inhibitory effects of sophocarpine on human liver cytochrome P450 enzymes

1. Sophocarpine is a biologically active component isolated from the foxtail-like sophora herb and seed that is often orally administered for the treatment of cancer and chronic bronchial asthma. However, whether sophocarpine affects the activity of human liver cytochrome P450 (CYP) enzymes remains unclear. 2. In this study, the inhibitory effects of sophocarpine on the eight human liver CYP isoforms (CYP1A2, 3A4, 2A6, 2E1, 2D6, 2C9, 2C19, and 2C8) were investigated in vitro using human liver microsomes (HLMs). 3. The results indicate that sophocarpine could inhibit the activity of CYP3A4 and 2C9, with the IC₅₀ values of 12.22 and 15.96 μM, respectively, but that other CYP isoforms were not affected. Enzyme kinetic studies showed that sophocarpine is not only a noncompetitive inhibitor of CYP3A4 but also a competitive inhibitor of CYP2C9, with K_i values of 6.74 and 9.19 μM, respectively. Also, sophocarpine is a time-dependent inhibitor of CYP3A4 with K_inact/K_I value of 0.082/21.54 μM^-1min^-1. 4. The in vitro studies of sophocarpine with CYP isoforms suggested that sophocarpine has the potential to cause pharmacokinetic drug interactions with other co-administered drugs metabolized by CYP3A4 and 2C9. Further clinical studies are needed to evaluate the significance of this interaction.

Pharmacokinetic Profile of Kaurenoic Acid after Oral Administration of Araliae Continentalis Radix Extract Powder to Humans

The objective of this study was to characterize pharmacokinetics (PKs) of kaurenoic acid (KAU) after administration of the clinical usual dose of Araliae Continentalis Radix extract powder to Korean subjects for the first time and evaluate the mechanism of its absorption in vitro. A simple, sensitive, and selective analytical method was developed for the detection of KAU in human plasma. Concentrations of KAU were quantified by ultra-performance liquid chromatography tandem mass spectrometry after simple liquid–liquid extraction. This pharmacokinetic model of KAU was best described by a two-compartment model with first-order absorption. To identify efflux transporters involved in the absorption of KAU, a Caco-2 monolayer model was used. Estimated PK parameters were: systemic clearance, 23.89 L/h; inter-compartmental clearance, 15.55 L/h; rate constant for absorption, 1.72 h⁻¹; volume of distribution of the central compartment, 24.44 L; and volume of distribution of the peripheral compartment, 64.05 L. Results from Caco-2 bidirectional transport study suggested that KAU was a potential substrate of efflux transporters. In summary, PKs of KAU were successfully characterized after administration of a usual dose of Araliae continentalis Radix extract powder in human with the newly developed bioanalytical method and the mechanism of absorption of KAU was identified clearly.

Absorption and Metabolism Characteristics of Triptolide as Determined by a Sensitive and Reliable LC-MS/MS Method

In this research, a sensitive and reliable LC-MS/MS method was developed and applied to determine the concentration of triptolide in rat plasma, microsomes, and cell incubation media. The absolute oral bioavailability of triptolide is 63.9% at a dose of 1 mg·kg⁻¹. In vitro, the bidirectional transport of triptolide across Caco-2 cells was studied. A markedly higher transport of triptolide across Caco-2 cells was observed in the basolateral-to-apical direction and was abrogated in the presence of the P-gp inhibitor, verapamil. The result indicated that P-gp might be involved in the absorption of triptolide in intestinal. The metabolic stability was also investigated using human liver microsome incubation systems in vitro. In HLMs, incubations with an initial triptolide concentration of 1 μM resulted in an 82.4% loss of substrate over 60 min, and the t_1/2 was 38 min, which indicated that triptolide was easily metabolized in human liver microsomes. In conclusion, the absolute oral bioavailability of triptolide in plasma, transport across Caco-2 cell monolayers, and metabolic stability in human liver microsomes were systematically investigated by using a sensitive and reliable LC-MS/MS method.