Grapefruit juice has no effect on quinine pharmacokinetics

Abstract

These results suggest that there is no significant interaction between the parent compound quinine and grapefruit juice, so it is not necessary to advise patients against ingesting grapefruit juice at the same time that they take quinine. Since quinine is a low clearance drug with a relatively high oral bioavailability, and is primarily metabolised by human liver CYP3A4, the lack of effect of grapefruit juice on quinine pharmacokinetics supports the view that the site of CYP inhibition by grapefruit juice is mainly in the gut.

Quinine as a potential tracer for medication adherence: A pharmacokinetic and pharmacodynamic assessment of quinine alone and in combination with oxycodone in humans

“…Quinine plasma concentrations were also examined after coadministration of oxycodone and quinine plasma AUC, C max , and T max and t 1/2 were unaltered in combination with oxycodone (Figure , Table ). These findings are supported by previous research indicating that potent CYP3A inhibitors (ketoconazole, troleandomycin), but neither moderate inhibitors (eg, grapefruit juice) nor CYP3A substrates (eg, oral contraceptives) interfere with quinine metabolism . Correspondingly, the pharmacokinetic profiles (C max , T max , t 1/2 ) of oxycodone and its CYP3A metabolite, noroxycodone, were similar across conditions (Figure , Table ); however, greater oxycodone and noroxycodone AUC values (+7%, +26%, respectively) were observed in the quinine condition.…”

Effect of grapefruit juice intake on etoposide bioavailability

“…[15,16]. P-glycoprotein (Pgp) which is also expressed in the brush border membrane of the small intestine, appears to play a considerable role in mechanisms of first-pass extractions of drugs, as recently reviewed [17].…”

Alteration of the Disposition of Quinine in Healthy Volunteers After Concurrent Ciprofloxacin Administration

“…The results show that the C max , AUC T , and elimination T 1/2 of quinine increased by 20% [95% confidence interval (CI), [15][16][17][18][19][20][21][22][23][24][25], 49% (95% CI, 42-57), and 32% (95% CI, [28][29][30][31][32][33][34][35][36], respectively, in the presence of ciprofloxacin. Also, the oral plasma clearance (CL/F) of quinine was highly reduced with concurrent ciprofloxacin administration by about 31% (95% CI, 28-34).…”

“…However, studies have shown that inhibition of the CYP 3A4 in the enterocytes by grapefruit juice (a potent inhibitor of intestinal CYP 3A4) does not affect the kinetics of quinine. 33 This suggests that the inhibitory activity of ciprofloxacin on quinine metabolism is majorly mediated by CYP 3A4 located in hepatocytes and not by that in enterocytes.…”