Interaction of pharmaceutical excipients with organic cation transporters

Effects of Commonly used Surfactants, Poloxamer 188 and Tween 80, on the Drug Transport Capacity of Intestinal Glucose Transporters

Some glycoside drugs can be transported through intestinal glucose transporters (IGTs). The surfactants used in oral drug preparations can affect the function of transporter proteins. This study aimed to investigate the effect of commonly used surfactants, Poloxamer 188 and Tween 80, on the drug transport capacity of IGTs. Previous studies have shown that gastrodin is the optimal drug substrate for IGTs. Gastrodin was used as a probe drug to evaluate the effect of these two surfactants on intestinal absorption in SD rats through pharmacokinetic and in situ single-pass intestinal perfusion. Then, the effects of the two surfactants on the expression of glucose transporters and tight-junction proteins were examined using RT-PCR and western blotting. Additionally, the effect of surfactants on intestinal permeability was evaluated through hematoxylin-eosin staining. The results found that all experimental for Poloxamer 188 (0.5%, 2.0% and 8.0%) and Tween 80 (0.1% and 2.0%) were not significantly different from those of the blank group. However, the AUC(0-∞) of gastrodin increased by approximately 32% when 0.5% Tween 80 was used. The changes in IGT expression correlated with the intestinal absorption of gastrodin. A significant increase in the expression of IGTs was observed at 0.5% Tween 80. In conclusion, Poloxamer 188 had minimal effect on the drug transport capacity of IGTs within the recommended limits of use. However, the expression of IGTs increased in response to 0.5% Tween 80, which significantly enhanced the drug transport capacity of IGTs. However, 0.1% and 2.0% Tween 80 had no significant effect.

Preparation and characterisation of self-emulsifying drug delivery system (SEDDS) for enhancing oral bioavailability of metformin hydrochloride using hydrophobic ion pairing complexation

AIM

The aim of this study was preparation of a self-emulsifying drug delivery system (SEEDS) containing metformin hydrochloride.

METHODS

Hydrophobic ion paired complexes were prepared by electrostatic interaction between metformin and sodium lauryl sulphate (SLS). The nanodroplets were optimised using two-level full factorial methodology and their morphology were examined. In vitro release of metformin from SEDDS was evaluated in simulated gastric and intestinal fluids. Finally, the ex-vivo efficacy of the optimised formulation in enhancing the intestinal permeability of metformin was evaluated using non-everted intestinal sac.

RESULTS

The data revealed that in weight ratio 1:4(metformin: SLS), the highest recovery was achieved. The physico-chemical properties of the optimised nano-droplets including size, polydispersity index (PdI), zeta potential, and loading efficiency (%) were 192.33 ± 9.9 nm, 0.275 ± 0.051; -1.52 mV, and 93.75 ± 0.77% (w/w), respectively.

CONCLUSIONS

The data obtained from the intestinal transport study demonstrated that SEDDS can significantly enhance the oral permeability of the compound.

The Effect of Ferulic Acid-Grafted Chitosan (FA-g-CS) on the Transmembrane Transport of Anthocyanins by sGLT1 and GLUT2

This work aims to evaluate the effect of ferulic acid-grafted chitosan (FA-g-CS) on the interaction between anthocyanin (ANC) and sGLT1/GLUT2 and their functions in ANC transmembrane transport using Caco-2 cells. The transmembrane transport experiments of ANC showed its low transport efficiency (Papp < 10⁻⁶ cm/s), whereas the phenomenon of a significantly rise in anthocyanins transport efficiency was observed with the incubation of FA-g-CS (p < 0.05). In order to investigate the mechanism of FA-g-CS improving ANC transmembrane transport, Caco-2 cells were transfected with small interfering RNA (siRNA) specific for transporters sGLT1 and GLUT2, and incubated with ANC, FA-g-CS, or their combination. Subsequently, Western blot analyses and immunofluorescence staining were carried out to monitor the intracellular sGLT1 and GLUT2 levels. These siRNA-transfected cells, incubated with compounds, indicate that sGLT1 and GLUT2 participated in the ANC transmembrane transport and that FA-g-CS, ANC, or their combination enhance sGLT1/GLUT2 expression. In particular, Caco-2 cells incubated with both FA-g-CS and ANC show significantly increased sGLT1 or GLUT2 expression (>80%) compared with exclusively using FA-g-CS or ANC (<60%). Molecular docking results demonstrate that there is a good binding between FA-g-CS/ANC and sGLT1 or GLUT2. These results highlight that FA-g-CS promotes the transmembrane transport of ANC by influencing the interaction between ANC and sGLT1/GLUT2; the interaction between FA-g-CS and ANC could be another key factor that improves the bioavailability of ANC.

Effect of Pharmaceutical Excipients on Intestinal Absorption of Metformin via Organic Cation-Selective Transporters

Growing evidence has shown that some pharmaceutical excipients can act on drug transporters. The present study was aimed at investigating the effects of 13 commonly used excipients on the intestinal absorption of metformin (MTF) and the underlying mechanisms using Caco-2 cells and an ex vivo mouse non-everted gut sac model. First, the uptake of MTF in Caco-2 cells was markedly inhibited by nonionic excipients including Solutol HS 15, polysorbate 20, polysorbate 40, polysorbate 60, polysorbate 80, and crospovidone. Second, transport profile studies showed that MTF was taken up via multiple cation-selective transporters, among which a novel pyrilamine-sensitive proton-coupled organic cation (H⁺/OC⁺) antiporter played a key role. Third, Solutol HS 15, polysorbate 40, and polysorbate 60 showed cis-inhibitory effects on the uptake of either pyrilamine (prototypical substrate of the pyrilamine-sensitive H⁺/OC⁺ antiporter) or 1-methyl-4-phenylpyridinium (substrate of traditional cation-selective transporters including OCTs, MATEs, PMAT, SERT, and THTR-2), indicating that their suppression on MTF uptake is due to the synergistic inhibition toward multiple influx transporters. Finally, the pH-dependent mouse intestinal absorption of MTF was significantly decreased by Solutol HS 15, polysorbate 20, polysorbate 40, polysorbate 60, polysorbate 80, and pyrilamine. In conclusion, this study revealed that a novel transport process mediated by the pyrilamine-sensitive H⁺/OC⁺ antiporter contributes to the intestinal absorption of MTF in conjunction with the traditional cation-selective transporters. Mechanistic understanding of the interaction of excipients with cation-selective transporters can improve the formulation design and clinical application of cationic drugs.

Biowaiver Monographs for Immediate Release Solid Oral Dosage Forms: Metformin Hydrochloride

Data are examined regarding possible waiver of in vivo bioequivalence testing (i.e. biowaiver) for approval of metformin hydrochloride (metformin) immediate-release solid oral dosage forms. Data include metformin's Biopharmaceutics Classification System (BCS) properties, including potential excipient interactions. Metformin is a prototypical transporter-mediated drug and is highly soluble, but only 50% of an orally administered dose is absorbed from the gut. Therefore, metformin is a BCS Class III substance. A BCS-based approval approach for major changes to marketed products and new generics is admissible if test and reference dosage forms have the identical active pharmaceutical ingredient and if in vitro dissolution from both are very rapid (i.e. at least 85% within 15 min at pH 1.2, 4.5, and 6.8). Recent International Council for Harmonisation BCS guidance indicates all excipients for Class III biowaivers are recommended to be qualitatively the same and quantitatively similar (except for preservatives, flavor agents, colorant, or capsule shell or film coating excipients). However, despite metformin being a prototypical transporter-mediated drug, there is no evidence that commonly used excipients impact metformin absorption, such that this restriction on excipients for BCS III drugs merits regulatory relief. Commonly used excipients in usual amounts are not likely to impact metformin absorption.

Inhibitory effect of sixteen pharmaceutical excipients on six major organic cation and anion uptake transporters

To date, relatively little is known about the interactions of pharmaceutical excipients with hepatic and renal drug uptake transporters. The present study was designed to systematically evaluate the effects of 16 commonly consumed excipients on human organic cation transporter 1 and 2 (hOCT1 and hOCT2), human organic anion transporter 1 and 3 (hOAT1 and hOAT3) and human organic anion transporting polypeptide 1B1 and 1B3 (hOATP1B1 and hOATP1B3). The inhibitory effects and mechanisms of excipients on transporters were investigated using in vitro uptake studies, cell viability assays, concentration-dependent studies, and the Lineweaver-Burk plot method. Triton X-100 is a non-competitive inhibitor for all six transporters. Tween 20 inhibits hOCT2, hOAT1, hOAT3, and hOATP1B3 in a mixed way, whereas it competitively inhibits hOATP1B1. The inhibition of Tween 80 is competitive for hOCT2, non-competitive for hOATP1B1 and hOATP1B3, and mixed for hOAT1 and hOAT3. Concentration-dependent studies identify Triton X-100 as a strong inhibitor of hOCT1 and hOCT2 with IC₅₀ values of 20.1 and 4.54 μg/mL, respectively. Additionally, Triton X-100, Tween 20, and Tween 80 strongly inhibit hOAT3 with IC₅₀ values ≤31.0 μg/mL. The present study is significant in understanding the excipient-drug interactions and provides valuable information for excipient selection in drug development.