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

Abstract

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 pyrilaminesensitive 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-4phenylpyridinium (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 cationselective transporters. Mechanistic understanding of the interaction of excipients with cation-selective transporters can improve the formulation design and clinical application of cationic drugs.

Investigation of the potential of Glycyrrhiza glabra as a bioavailability enhancer of Vitamin B12

“…Hundred microliter of serosal fluid was transferred to 96 wells plate and Vitamin B12 was quantitated from the standard curve by measuring absorbance at 360 nm. Area of each sac was calculated considering it a cylinder (length 4 cm, width/diameter 0.5 cm, radius 0.25 cm) ( 20 ). Two experiments were performed, each with two replicates comprising everted gut sacs treated with B12 only (100 μg/ml) and combination of B12+GgEtOH (250 and 500 μg/ml).…”