Coadministration Of Grapefruit Juice Research Articles

Abstract 4648: Development and validation of an HPLC-UV method for Sirolimus (sir) quantification in human blood and application to cancer patients in routine clinical practice

Abstract Background and objective: After oral administration, SIR (mTOR inhibitor) is rapid absorbed with a bioavailability around 14%. SIR is distributed mostly into red blood cells, 92% is bound to proteins and its apparent steady state volume of distribution is higher than 650 L. The apparent clearance has been determined to be 13 L/h. SIR undergoes extensive hepatic and intestinal metabolism via CYP3A4 and CYP3A5, as well as excretion by P-glycoprotein. The purpose of this study was to develop a simple and sensitive HPLC method with UV-Visible detection for SIR blood quantification to allow therapeutic drug monitoring (TDM) in cancer patients. A pilot phase I study in advanced cancer patients was initiated to evaluate the effect of grapefruit juice in SIR pharmacokinetics. Methods: After a liquid-liquid extraction with 1-chlorobutane, SIR and paclitaxel (internal standard, IS) are separated in Ultrabase C18 column using a mobile phase consisting of a mixture of methanol and water in a proportion 77:23 pumped at a constant flow rate of 1 mL/min. The column was maintained at 50°C and the eluent was monitored at a wavelength of 277 nm. Validation experiments were carried out after the guidelines for Bioanalytical Method Validation published by the FDA and the EMA. SIR was administered once weekly as an oral solution in three dose leves (10, 20 or 30 mg). Natural grapefruit juice (250 cc) was administered half an hour before SIR administration, once a week. Results: The calibration curve was linear in the range of 10-700 ng/mL. The limit of quantification was determined to be 10 ng/mL. SIR and IS retention times were 12.2 and 3.4 min, respectively. Inter- and intra-day coefficients of variation were less than 8%. The mean extraction recovery from plasma was higher than 67%. In the first six patients evaluated, SIR blood concentrations were well quantified and showed that the analytical method was capable of measuring the blood concentrations of SIR in advanced cancer patients undergoing SIR therapy. In all patients, SIR concentrations were significantly increased by grapefruit juice at all dose levels because its clearance was reduce around 50% confirming previous results published by Cohen E et al. (Clin Cancer Res, 2012). Conclusion: The simple, rapid and sensitive HPLC-UV method developed and validated for the measurement of SIR in human blood using paclitaxel as IS can be applied easily in routine clinical practice for the TDM of SIR. Co-administration of grapefruit juice and SIR must be evaluated in the context of Phase II and III clinical trials in order to explore alternative and safer treatments. Note: This abstract was not presented at the meeting. Citation Format: Vanesa Escudero-Ortiz, Belen Valenzuela, Joseba Rebollo, Manuel Sureda, Antonio Brugarolas. Development and validation of an HPLC-UV method for Sirolimus (sir) quantification in human blood and application to cancer patients in routine clinical practice. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4648. doi:10.1158/1538-7445.AM2014-4648

Effect of ciprofloxacin and grapefruit juice on oral pharmacokinetics of riluzole in Wistar rats

The objective of this study was to explore potential drug-drug/food interactions of ciprofloxacin and grapefruit juice, known hepatic cytochrome P450 (CYP) 1A2 inhibitors, on single-dose oral pharmacokinetics of riluzole, a substrate of CYP 1A2 enzymes. Pharmacokinetic parameters of riluzole were determined in Wistar rats after single-dose co-administration with ciprofloxacin and grapefruit juice. In-vitro metabolic inhibition studies using rat and human liver microsomes and intestinal absorption studies of riluzole in a rat everted gut-sac model were conducted to elucidate the mechanism of interaction. A validated HPLC method was employed to quantify riluzole in the samples obtained in various studies. Co-administration of ciprofloxacin with riluzole caused significant increase in systemic exposure of riluzole (area under the curve, maximum plasma concentration and mean residence time were found to increase). Co-administration of grapefruit juice with riluzole did not cause any significant difference in the pharmacokinetic parameters of riluzole. In-vitro metabolism studies demonstrated significant inhibition of riluzole metabolism when it was co-incubated with ciprofloxacin or grapefruit juice. No significant change was observed in apparent permeability of riluzole. Co-administration of ciprofloxacin with riluzole increases the systemic levels of riluzole and thereby the oral pharmacokinetic properties of riluzole while co-administration of grapefruit juice with riluzole has no significant effect.

Grapefruit juice, lyophilized grapefruit juice, and powdered whole grapefruit inhibit cytochrome P450-mediated triazolam hydroxylation by beagle dog liver microsomes

Coadministration of grapefruit juice (GFJ) has been proposed to enhance the systemic availability and decrease the required dose of drugs such as cyclosporine that are extensively metabolized in the intestine and liver. Although GFJ inhibits human cytochrome P450 (CYP) 3A, effects on dog CYP have not yet been reported. Consequently, we determined whether GFJ inhibits triazolam hydroxylation by Beagle dog liver microsomes (DLM) using human liver microsomes (HLM) as positive control. Results were compared with the effects of lyophilized GFJ and commercially-available powdered grapefruit capsules, which may be more convenient dosage forms. GFJ inhibited alpha-hydroxytriazolam formation in both DLM and HLM with similar IC(50) (inhibitor concentration producing a 50% decrease in reaction velocity) values of 0.56% and 0.52% (v/v), respectively. Lyophilized GFJ and powdered grapefruit also inhibited DLM alpha-hydroxytriazolam formation with IC(50) values of 0.76 and 1.2 mg/mL, respectively. Consistent with mechanism-based enzyme inhibition, preincubation of DLM with any of the grapefruit products for 20 min resulted in significant enhancement of inhibition of triazolam alpha-hydroxylation by 8-20%. The results indicate that 16 g of lyophilized GFJ or 23 g of powdered grapefruit would be equivalent to dosing 100 mL of GFJ. In vivo pharmacokinetic interaction studies are needed to confirm these in vitro findings.

Co-administration of grapefruit juice increases bioavailability of tacrolimus in liver transplant patients: a prospective study

The interactions between grapefruit juice (GFJ) and tacrolimus (FK506) metabolism remain obscure. The aim of this prospective study was to explore the effect of GFJ on the blood concentration of FK506 in liver transplant patients. Thirty liver transplant patients were enrolled in the study 1 month post-transplant and randomly divided into three equal-sized groups. Group A patients were treated with the standard FK506-based immunosuppressant regimen only and therefore served as the control; group B and C patients were treated with the standard FK506-based immunosuppressant regimen as well as one of two different kinds of GFJ, respectively. The blood concentrations of FK506 on the seventh day after GFJ intake were compared within each group and among groups. The dose of FK506 was adjusted depending on the valley concentration measured to a treatment window. The blood concentration of FK506 in both group B and group C patients was significantly enhanced, by 1.56 +/- 0.95 and 10.33 +/- 5.59 ng/ml, respectively, following the administration of GFJ for 1 week (compared with the concentration at the start of the experiment in each group; p < 0.05). However, at the end time point, the blood concentration of FK506 in group C patients was significantly increased (p < 0.05) relative to that of the control patients, while this was not the case in group B patients (p > 0.05). Group C patients could be treated with a smaller dose of FK506 (decreased by 2.3 +/- 1.3 mg/day for all patients; p = 0.011), amounting to a decrease in drug costs of approximately $8.70 +/- 5.60/day (p = 0.011). In the setting of a controlled clinical study, the co-administration of GFJ with FK506 increased the bioavailability of FK506. However, the concentration of tacrolimus should be closely monitored and the dose adjusted to the treatment window.

P1369 Modification of cephalexin serum concentration by grapefruit juice co-administration in rats

P1369 Modification of cephalexin serum concentration by grapefruit juice co-administration in rats

Enhanced Role of Grapefruit Juice on the Antischistosomal Activity of Artemether on the Liver of Schistosoma haematobium Infected Hamsters

Artemether (ART) is an efficacious anti-malarial drug that also displays antischistosomal properties. Laboratory studies have found that ART curtails the development of schistosoma worms and thus prevents morbidity. Grapefruit juice was found to interact with various drugs that have been metabolized by a form of Cytochrome P450, CYP3A4, thus increasing the plasma drug concentration. This work aimed to study the effect of grapefruit juice when administered before infection with Schistosoma haematobium and/or treatment with ART on its anti-schistosomal activity. Golden hamsters were infected each with 300 S. haematobium cercariae and divided into 6 groups (A – F), as follows: Infected control (A); infected received grapefruit juice before infection (B); or received grapefruit juice before infection and treated with ART (200 mg/k) at 5,6 and 7 weeks post infection (WPI) (C); or for 3 successive doses at 12 WPI (D); infected treated with ART alone (200 mg/k) at 5,6 and 7 WPI (E); infected received grapefruit juice (0.5 ml) half an hour before treatment with ART (200 mg/k) at 5,6 and 7 WPI (co-administration) (F). All groups were sacrificed 14 WPI. Some parasitological, biochemical and histopathological estimations were done. Results revealed that, the highest percent of worm reduction was observed in-group F (94.2%) compared to group C,E &amp; D (87.3%, 77.6% &amp; 65.9% respectively). The level of ALT, GGT, urea, thiol, albumin and alkaline phosphatase tend to normalize in accordance with the parasitological results. Neither hepatic granuloma nor prominent histopathological changes could be detected in group F. A minimal number of granulomas (1-3/animal) was observed in group E; meanwhile, the least diameter and collagen content of hepatic S. haematobium granulomas were observed in group C (125.6±5.5 &amp; 2.4±0.572 respectively). The results of the present study demonstrated that, co-administration of grapefruit juice just before treatment with ART at 5, 6&amp; 7 WPI enhanced its anti-schistosomal activity and improved the histopathological changes.

Effect of grapefruit juice on cabergoline pharmacokinetics in patients with Parkinson's disease

Background Cabergoline is one of the synthetic ergoline dopamine agonists, which is widely used for the treatment of Parkinson's disease (PD). Cytochrome P-450 (CYP) 3A4 contributes to metabolize Cabergoline. It has been well known that grapefruit juice inhibits CYP3A4 enzyme located in the gut wall. To investigate whether grapefruit juice influences the pharmacokinetics of cabergoline, plasma level of cabergoline in patients of PD was evaluated. Methods Five patients with PD treated with cabergoline were enrolled. Plasma concentrations of cabergoline before and after coadministration of grapefruit juice were evaluated. The plasma concentration of cabergoline was determined using a LC/MS/MS. Results The plasma concentration of cabergoline increased approximately 1.7 times, when grapefruit juice was taken together with cabergoline. Adverse events were not observed during this trial. Conclusions Coadministration of grapefruit juice with cabergoline increases bioavailability of cabergoline. A relatively large therapeutic window of cabergoline may allow the concomitant treatment with grapefruit juice, and this combination treatment may augment the antiparkisonian effect of cabergoline. Clinical Pharmacology & Therapeutics (2005) 77, P84–P84; doi: 10.1016/j.clpt.2004.12.213

Effects of Itraconazole or Grapefruit Juice on the Pharmacokinetics of Telithromycin

To determine whether coadministration of the cytochrome P450 3A4 (CYP3A4) inhibitors itraconazole or grapefruit juice will modify the pharmacokinetic profile of telithromycin, and to assess the safety of telithromycin. Two single-center, open-label studies; the itraconazole study was nonrandomized, sequential, and multiple dose, and the grapefruit juice study was randomized, two-period crossover, and single dose. Two clinical investigative centers in the United States. Thirty-four healthy, nonsmoking male volunteers aged 18-45 years. All patients received telithromycin 800 mg/day; 18 patients received concomitant itraconazole 200 mg/day, and 16 received concomitant single-dose, single-strength grapefruit juice. Standard pharmacokinetic and safety measurements were performed. Itraconazole given concomitantly with telithromycin increased the steady-state area under the plasma concentration-time curve from 0-24 hours of telithromycin by 53.8% (p<0.0001). Coadministration of grapefruit juice did not affect telithromycin pharmacokinetic parameters, and telithromycin was well tolerated in both studies. Only modest changes in the pharmacokinetics of telithromycin were seen with concomitant administration of itraconazole. Telithromycin pharmacokinetics were unaffected by concomitant administration of grapefruit juice.

Effect of artemether alone and in combination with grapefruit juice on hepatic drug-metabolising enzymes and biochemical aspects in experimental Schistosoma mansoni

Artemether is an efficacious antimalarial drug that also displays antischistosomal properties. Grapefruit juice increases the oral availability of a variety of the CYP3A4 substrates. This study was designed to evaluate the effect of repeated administration of grapefruit juice with artemether on the hepatic activities of cytochrome P-450 (CYP450) and cytochrome b5 (cyt b5), on the serum levels of some biochemical enzymes and antischistosome efficacy. Results showed that administration of grapefruit juice alone induced more inhibition in the hepatic activities of CYP450 and cyt b5 than that produced by Schistosoma mansoni infection. Moreover, it enhanced degeneration of eggs and accelerated healing of the pathological granulomatous lesions. Treatment of S. mansoni-infected mice with artemether at a total dose of 300 mg/kg resulted in total and female worm burden reductions of 66.7 and 90.1%, respectively, hence protecting the host from damage induced by schistosome eggs. Treatment of S. mansoni-infected mice with artemether at 150 mg/kg reduced the total and female worm numbers by 43.3 and 54.4%, respectively, thus somewhat ameliorating hepatic granulomatous lesions compared with the infected untreated group. This was associated with no change in the hepatic activities of CYP450 and cyt b5 and in the serum levels of total protein, albumin, globulin and alanine aminotransferase compared with the uninfected control group. Coadministration of grapefruit juice with the lower dose (150 mg/kg) of artemether eliminated eggs and granulomatous reactions. In this group, the inhibitory effects of grapefruit juice on CYP450 and cyt b5 were apparent but serum liver enzymes were unchanged compared with the uninfected control group. Coadministration of grapefruit juice with artemether achieved complete protection of the host from damage induced by schistosomal infection.

Development of a liquid chromatographic method for bioanalytical applications with sildenafil

An improved HPLC method was developed for the determination of sildenafil concentrations in plasma. Analysis of sildenafil in plasma samples was simplified by utilizing a one-step liquid–liquid extraction after alkaline treatment of only 1 ml of plasma. The lower limit of quantitation was 10 ng/ml with a coefficient of variation of less than 20%. A linear range was found to exist from 10 to 1000 ng/ml. This HPLC method was validated with precisions (coefficient of variation, C.V.) for inter- and intra-day runs of 0.41–11.15% and 0.36–8.05%, respectively, and accuracies (the relative error of the mean, REM) for inter- and intra-day runs of −8.72–6.81% and 0.41–11.15%, respectively. A bioavailability study of sildenafil was performed on one normal healthy male volunteer by analyzing sildenafil plasma concentrations with this validated HPLC method. Results demonstrated that this HPLC method is appropriate for applications to bioavailability studies of sildenafil. In addition, an example of the influence of the co-administration of grapefruit juice on sildenafil pharmacokinetics in a healthy volunteer is presented.

Grapefruit juice potentiates the anti-inflammatory effects of diclofenac on the carrageenan-induced rat’s paw oedema

The anti-inflammatory effect of diclofenac alone or in combination with double strength grapefruit juice was investigated on carrageenan-induced rat’s paw oedema. Paw was measured by using a plethysmometer 3 h after injecting the phlogestic agent. There was significant inhibition (P< 0.05) of the oedematous response after oral administration of diclofenac alone (1, 2.5, 5 mg kg−1p.o.) in a dose-dependent manner. Coadministration of grapefruit juice (10 ml kg−1p.o.) orally with all doses of diclofenac, enhanced the inhibitory effect of diclofenac on rat’s paw oedema. Double-strength grapefruit juice has synergistic inhibitory effect on rat’s paw oedema when administered in combination with diclofenac.

Inhibition of the CYP3A4-mediated metabolism and P-glycoprotein-mediated transport of the HIV-1 protease inhibitor saquinavir by grapefruit juice components.

Cytochrome P450 3A4 (CYP3A4) and P-glycoprotein (P-gp) are both expressed in the intestinal mucosa and present a barrier to oral drug delivery. CYP3A4 and P-gp share both overlapping tissue distribution and substrate specificity. Grapefruit juice interactions with CYP3A4 substrates are well documented and occur as a consequence of down regulation of intestinal CYP3A4. The aim of the present study was to screen grapefruit juice components against the CYP3A4-mediated metabolism and P-gp mediated transport of the HIV-1 protease inhibitor saquinavir. Five grapefruit juice components: quercetin, naringin, naringenin, 6', 7'-dihydroxybergamottin and bergamottin were screened as potential inhibitors of the metabolism of saquinavir by human liver microsomes. The known CYP3A4 inhibitor ketoconazole was also screened for inhibitory potential. These compounds were also screened as modulators of P-gp activity by assessing the directional transport of saquinavir across Caco-2 cell monolayers which express P-gp. The effect of verapamil, a known modulator of P-gp function, was also determined in these cell lines. On preincubation, 6', 7'-dihydroxybergamottin and bergamottin inhibited the metabolism of saquinavir, with IC50 values of 0.33+/-0.23 muM and 0.74+/-0.13 muM, respectively (n=3). Ketoconazole achieved an IC50 of 0. 55+/-0.12 muM (n=4). The other compounds studied failed to reach IC50 at concentrations of up to 100 muM. The transport of saquinavir in the basolateral-->apical (BL-->AP) direction exceeded that in the apical -->basolateral direction (AP-->BL), with apparent permeability coefficients of 199.2+/-15.8x10-7 cm s-1 and 8.00+/-1. 13x10-7 cm s-1, respectively (n=3) which is indicative of a polarized efflux mechanism. The ratio of BL-->AP/AP-->BL for saquinavir was 25, but in the presence of verapamil and ketoconazole this ratio was reduced to 3.6 and 4.0, respectively (n=3), indicating extensive inhibition of P-gp mediated saquinavir efflux. Of the grapefruit juice components studied only naringin and 6', 7'-dihydroxybergamottin had any appreciable effect, reducing the ratio to 7.6 and 7.1, respectively (n=3); but this was due solely to increased AP-->BL transport. Grapefruit juice components inhibit CYP3A4-mediated saquinavir metabolism and also modulate, to a limited extent, P-gp mediated saquinavir transport in Caco-2 cell monolayers. The in vivo effects of grapefruit juice coadministration are most likely the result of effects on CYP3A4 (inhibition and down regulation) and only to a minor extent on modulation of P-gp function.

Lack of significant pharmacokinetic interaction between haloperidol and grapefruit juice.

The effects of repeated ingestion of grapefruit juice, an inhibitor of cytochrome P4503A4 (CYP3A4), on the steady-state plasma concentrations of haloperidol and reduced haloperidol were examined. Twelve schizophrenic inpatients receiving haloperidol 12 mg/day, ingested grapefruit juice 600 ml/day for 7 days. Blood samples were collected before and during grapefruit juice coadministration and 1 week after its discontinuation together with an assessment of clinical status. Plasma drug concentrations were measured using high-performance liquid chromatography. Clinical status for each patient was assessed by the Brief Psychiatric Rating Scale (BPRS) and the UKU side-effect rating scale (UKU). Plasma concentrations of haloperidol and reduced haloperidol during grapefruit juice coadministration (9.0 +/- 3.0 and 2.6 +/- 1.4 ng/ml, respectively) were not significantly different from those before grapefruit juice coadministration (9.1 +/- 2.8 and 2.6 +/- 1.5 ng/ml) or those 1 week after its discontinuation (8.8 +/- 2.7 and 2.6 +/- 1.3 ng/ml). There was no change in the scores of BPRS or UKU during the study period. The present results shows that grapefruit juice does not affect the plasma concentrations of haloperidol and reduced haloperidol or clinical status in patients receiving haloperidol.

Pharmacokinetics of Tacrolimus (FK506) in Various Conditioning Renal Transplant Recipients

247 (Purpose) Tacrolimus is usually administered based on a mg/kg or the trough concentration (Cmin) in whole blood. But it is not easy to determine the optimal dose because of considerable interindividual variation of tacrolimus bioavailability between patients. Therapeutic drug monitoring of tacrolimus is mandatory. We investigated pharmacokinetics of tacrolimus in various conditioning renal transplant recipients. (Methods) Pharmacokinetic investigations were performed after kidney transplantation in various conditioning. 1) 30 patients were investigated in daily profile of tacrolimus blood levels. 2) 4 patients were evaluated the effects of meal timing on the bioavailability of tacrolimus. Tacrolimus was given to overnight fasted subjects and 0.5 hours after a breakfast in each patient. 3) 3 patients were taken grapefruit juice with tacrolimus and were measured tacrolimus level. (Results) There was a strong correlation between AUC and the trough concentration of tacrolimus (Cmin) in whole blood (r=0.745,P <0.001) and was only a weak correlation between dose per kilogram body-weight and AUC. Significant increases in the maximum concentration (Cmax) to 223% and in the AUC to 157% of 0.5 hours after the meal were seen in the overnight fasted subjects.TableThere was no significant effect in tacrolimus absorption in patients with grapefruit juice. Table(Conclusion) The strong correlation between AUC and the trough concentrations of tacrolimus (Cmin) indicates that trough levels are good indicators of systemic exposure. Since tacrolimus absorption was better under fasted conditions than under the presence of food, tacrolimus should be administered at least 1 hour before the meal. Co-administration of grapefruit juice was not useful in reducing tacrolimus dose in our study.