Effect of furanocoumarin derivatives in grapefruit juice on the uptake of vinblastine by Caco‐2 cells and on the activity of cytochrome P450 3A4

Abstract

1 The presence of inhibitors of drug e ux transporters, such as P-glycoprotein (P-gp), in grapefruit juice (GFJ) was con®rmed based on the uptake of [ 3 H]-vinblastine (VBL) by Caco-2 cells. 2 The uptake of [ 3 H]-VBL by Caco-2 cells was signi®cantly increased by the ethyl acetate extract of GFJ as well as by cyclosporin A. The extract was separated on a Cosmosil column and the eluate with 60% methanol increased [ 3 H]-VBL uptake, while the activity to inhibit CYP3A4 was greatest in the 70 and 80% eluates. 3 These results show that the major inhibitor of e ux transport of VBL is di erent from that of CYP3A4. 4 Further separation of the 60% methanol eluate a orded dihydroxybergamottin (DHBG). Both ethyl acetate extract of GFJ and DHBG increased steady-state [ 3 H]-VBL uptake by LLC-GA5-COL300 cells. Besides DHBG, other furanocoumarins contained in GFJ, such as bergamottin, FC726, bergaptol and bergapten, increased the steady-state uptake of [ 3 H]-VBL by Caco-2 cells. 5 The order of inhibitory potency of these compounds was FC7264DHBG4bergamottin4ber-gapten4bergaptol. While, the IC 50 values for inhibition of CYP3A4 were 0.075, 0.45, 1.0, 1.0 and 420 mM, respectively. Bergaptol speci®cally inhibited VBL e ux. 6 DHBG was thus identi®ed as a candidate for inhibitors of VBL transport, together with other furanocoumarins. Moreover, partly involvement of the P-gp inhibition was suggested. 7 Therefore, the inhibition of e ux transport of drugs as well as of drug metabolism by CYP3A4 could be an important cause of drug-GFJ interaction.

Food–drug interaction: grapefruit juice augments drug bioavailability—mechanism, extent and relevance

“…Most of these studies reported further decreases in diastolic blood pressure when felodipine was taken with grapefruit juice, as well as increase in haemodynamic-related adverse effects such as increased heart rate and orthostatic hypotension (Bailey et al, 1991;Lundahl et al, 1997Lundahl et al, , 1998. Other dihydropyridines exhibiting the interaction to a similar extent are nisoldipine (Bailey et al, 1993b;Takanaga et al, 2000) and nicardipine . A milder but significant interaction has been detected with nitrendipine, pranidipine and nimodipine that exhibited bioavailability increments of 100, 73 and 50%, respectively (Soons et al, 1991;Fuhr et al, 1998;Hashimoto et al, 1998).…”

“…The prolongation of the interaction is consistent with the pharmacological mechanism of the interaction, since biosynthesis of a new enzyme is necessary. Up to 3 days persistence of the juice impact is reported (Takanaga et al, 2000); however, it appears that an interval of 24 h between ingestion of grapefruit juice and a drug can usually prevent a potential clinically relevant interaction (Lilja et al, 2000b).…”

“…The major furanocoumarin present in grapefruit is bergamottin, which demonstrates a time-and concentration-dependent inactivation of CYP enzymes in vitro (He et al, 1998), as well Food-drug interaction A Dahan and H Altman as its metabolite 6 0 ,7 0 -dihydroxybergamottin (DHB) and a number of other furanocoumarin derivatives (Ohnishi et al, 2000;Mohri & Uesawa, 2001). DHB, along with four newly isolated furanocoumarins have reproduced roughly the inhibitory potency of grapefruit juice when mixed together, while the omission of any of the components resulted in decreased potency, suggesting that all major furanocoumarins contribute to the properties of grapefruit juice .…”

Expression of P-glycoprotein in HeLa cells confers resistance to ceramide cytotoxicity

“…The following day the medium was replaced with 1% FBS medium and cells were exposed to the vehicle (control), tamoxifen, verapamil, or cyclosporin A (all at 10 μM) for 60 min, after which [ 3 H]vinblastine (15.6 nM final concentration) was added to each well and cells were incubated for 60 min and 37˚C. The uptake of vinblastine was determined as previously described (36). …”

“…The cells (P-gp/on) were seeded in 12-well plates (50,000 cells/well) and the [ 3 H]vinblastine uptake was measured in the absence and presence of tamoxifen, verapamil, or cyclosporin A (all at 10 μM) following the method used by Ohnishi et al (36).…”