PHAR 751 Dietary Effects on Metabolism Sarah Brown, Pharm.D. Pharmacy Practice Resident Asante Health System sbrown@asante.org

Metabolism: P-gp review Substrate + Inhibitor = Substrate + Inducer =

CYP Metabolism Cytochrome P450 Gene superfamily: families subfamilies enzyme Oxidative metabolism – Phase I Location Liver Small intestine Most abundant P450 is CYP3A4 Induction = Inhibition =

Metabolism: CYP review Substrate + Inhibitor = Substrate + Inducer =

Metabolism & Diet Food Macronutrients Protein CHO Fats Micronutrients Vitamins Minerals Indoles Drink Grapefruit juice Orange juice Seville orange juice Alcohol  Diet can alter enzyme activity  influence the intensity & duration of action

Macronutrients: Protein Intake 20% of diet Malnutrition contributes to variability in drug metabolism CYP-mediated In rats: CYP3A activity ↓ from 18% to 1% w/ ↓protein intake CYP1A2 ↓ w/ 0.5% protein diet CYP1A1: no change

Protein intake & theophylline metabolism CYP-mediated ↓ in Cl of 30% when reduce protein intake from 20% to 10% ↓ t½ from 8-9 h to 6 h by increasing protein from 10% to 40%. TPN patients  lower plasma Cl

Another route of metabolism: FMO1 Flavin-containing monooxygenase (FMO) 1 protein Oxidative metabolism Non-inducible Influenced by dietary intake

Micronutrient: Indole effect on metabolism Indole-3-carbinol (I3C) Naturally-occurring chemical found in cruciferous vegetables Induces CYP1A1 Inhibits FMO1 Also marketed as dietary supplement Katchamart, et al. Concurrent flavin-containing monooxygenase down-regulation and cytochrome p-450 induction by dietary indoles in rat: implications for drug-drug interaction. Drug Metabolism and Disposition 2000; 28 (8): 930 – 936.

Influence of dietary I3C on FMO1 protein levels Four weeks of I3C or DIM in diet of rats Dose-dependent reduction in liver FMO1 protein levels. Higher dose of I3C, 2500 ppm, reduced levels to 10% that of controls. At same concentration, DIM was more potent, reducing to 3% of control. Katchamart, et al. Concurrent flavin-containing monooxygenase down-regulation and cytochrome p-450 induction by dietary indoles in rat: implications for drug-drug interaction. Drug Metabolism and Disposition 2000; 28 (8): 930 – 936.

FMO (-) and CYP (+) Dose-dependent inhibition of FMO formation of n-oxide. Not dose dependent: induction of CYP-dependent N-demethylation. Again, DIM, more potent than I3C. Katchamart, et al. Concurrent flavin-containing monooxygenase down-regulation and cytochrome p-450 induction by dietary indoles in rat: implications for drug-drug interaction. Drug Metabolism and Disposition 2000; 28 (8): 930 – 936.

Micronutrient: Indole effect on metabolism of tamoxifen Dietary I3C reduced N-oxygenation of tamoxifen by liver microsomes without increase in CYP-dependent N-demethylation. Katchamart, et al. Concurrent flavin-containing monooxygenase down-regulation and cytochrome p-450 induction by dietary indoles in rat: implications for drug-drug interaction. Drug Metabolism and Disposition 2000; 28 (8): 930 – 936.

Why do we care? Clinical relevance Drug-drug or drug-food interactions Potential for altered toxicity of drugs that are substrates for FMO and CYP Potential altered efficacy (i.e. tamoxifen) I3C & DIM dietary supplements

Alcohol & Tobacco effects on metabolism 80 – 95% alcoholics smoke (25 – 30% non-alcoholics smoke) 70% are heavy smokers Those who drink & smoke  more cigarettes/day Correlation between alcohol intake & tobacco use Association w/ environmental and genetic factors? Schoedel KA, Tyndale RF. Induction of nicotine-metabolizing CYP2B1 by ethanol and ethanol-metabolizing CYP2E1 by nicotine: summary and implications. Biochimica et Biophysica Acta 1619 (2003) 283– 290.

Alcohol & Nicotine: types of tolerance Cross tolerance Functional cross-tolerance Metabolic cross-tolerance Schoedel KA, Tyndale RF. Induction of nicotine-metabolizing CYP2B1 by ethanol and ethanol-metabolizing CYP2E1 by nicotine: summary and implications. Biochimica et Biophysica Acta 1619 (2003) 283– 290.

Alcohol & Nicotine metabolism Primarily by ADH 20% by CYP2E1 (up to 60% at high BAC) Nicotine Metabolized by CYP2A6 (and CYP2B6 in humans; CYP2B1 in rats ) cotinine (inactive) Schoedel KA, Tyndale RF. Induction of nicotine-metabolizing CYP2B1 by ethanol and ethanol-metabolizing CYP2E1 by nicotine: summary and implications. Biochimica et Biophysica Acta 1619 (2003) 283– 290.

CYP2E1 CYP2E1 Also metabolizes APAP, isoniazid, tamoxifen, halothane Inducible by both EtOH & nicotine Potential for altering efficacy of clinically used substrates Schoedel KA, Tyndale RF. Induction of nicotine-metabolizing CYP2B1 by ethanol and ethanol-metabolizing CYP2E1 by nicotine: summary and implications. Biochimica et Biophysica Acta 1619 (2003) 283– 290.

Alcohol + Nicotine + CYP2E1 = ? ↑ expression of CYP2E1 (induced by nicotine and EtOH) ↑ metabolism of EtOH = metabolic cross-tolerance  more EtOH required for same effect = tolerance Schoedel KA, Tyndale RF. Induction of nicotine-metabolizing CYP2B1 by ethanol and ethanol-metabolizing CYP2E1 by nicotine: summary and implications. Biochimica et Biophysica Acta 1619 (2003) 283– 290.

Study in rats Up-regulation of brain CYP2B1 & CYP2E1 by EtOH  Nicotine metabolized by CYP2B1 = metabolic cross tolerance Schoedel KA, Tyndale RF. Induction of nicotine-metabolizing CYP2B1 by ethanol and ethanol-metabolizing CYP2E1 by nicotine: summary and implications. Biochimica et Biophysica Acta 1619 (2003) 283– 290.

Metabolism & Diet √ Food – protein √ Drink – alcohol next: citrus juices

Flavonoids Naturally occurring in citrus fruits Known for antioxidant activity Flavonoids Flavone Flavanone Flavonol Potential for drug-interactions

PK Study: Felodipine & Grapefruit juice Substrate: felodipine Enzyme inhibitor: grapefruit juice Inhibits CYP3A4 & CYP1A2 What happens to felodipine concentrations? Lown et al. Grapefruit Juice Increases Felodipine Oral Availability in Humans by Decreasing Intestinal CYP3A Protein Expression. J Clin Invest. 1997; 99(19): 2545-2553.

Naringin A flavonoid Metabolized to the flavonone, naringenin “bitter” component of grapefruit juice 800 mg/L ~100 g flesh = 200 mL regular strength juice Inhibits CYP3A4 & CYP1A2

Quercetin A Flavonol Average daily intake 16 – 25 mg/day Adjunct to cisplatin, cyclophosphamide, and adriamycin tx Chelates metal ions; acts as free radical scavenger ↓ CAD mortality; ↓ stroke incidence Dietary supplementation: 1 – 1.5 g/day Known to inhibit oxidation of nifedipine and felodipine

Felodipine A dihydropyridine calcium channel blocker Reversibly competes w/ other CCBs for dhp-binding sites Blocks voltage-dependent Ca2+ currents in vascular smooth muscle

Felodipine + Grapefruit juice Study: Recurrent administration of grapefruit juice & felodipine kinetics Hypothesis: continuous administration of grapefruit juice  increased intestinal CYP3A4  diminishing effect on felodipine kinetics Lown et al. Grapefruit Juice Increases Felodipine Oral Availability in Humans by Decreasing Intestinal CYP3A Protein Expression. J Clin Invest. 1997; 99(19): 2545-2553.

CYP3A4 concentration in study participants Drop in the CYP3A4 enterocyte concentration in all subjects Decreased by 62% fromd D5 to D12. Greater drop in concentration if started at higher concentration Lown et al. Grapefruit Juice Increases Felodipine Oral Availability in Humans by Decreasing Intestinal CYP3A Protein Expression. J Clin Invest. 1997; 99(19): 2545-2553.

↓ CYP3A4 following GFJ administration Lown et al. Grapefruit Juice Increases Felodipine Oral Availability in Humans by Decreasing Intestinal CYP3A Protein Expression. J Clin Invest. 1997; 99(19): 2545-2553.

All CYPs? Or just 3A4? “…no consistent change in the level of enterocyte CYP2D6 or CYP1A1 protein with recurrent grapefruit juice ingestion.” Lown et al. Grapefruit Juice Increases Felodipine Oral Availability in Humans by Decreasing Intestinal CYP3A Protein Expression. J Clin Invest. 1997; 99(19): 2545-2553.

Clinical interactions: felodipine & GFJ ∆ = after 5 days GFJ tid ○ = after first glass GFJ ● = Water With first glass of grapefruit juice: 225% increase in Cmax. Also 116% increase in AUC Effect does not diminish with continued ingestion – after 16th glass of GFJ, Cmax increased 34% and AUC 44% over respective mean values with initial glass. Magnitude varied considerably among the 10 subjects Lown et al. Grapefruit Juice Increases Felodipine Oral Availability in Humans by Decreasing Intestinal CYP3A Protein Expression. J Clin Invest. 1997; 99(19): 2545-2553.

Conclusion: Felodipine + Grapefruit juice Study: Recurrent administration of grapefruit juice & felodipine kinetics Hypothesis: continuous administration of grapefruit juice  increased intestinal CYP3A4  diminishing effect on felodipine kinetics Result: decrease in intestinal CYP3A4 in all subjects Lown et al. Grapefruit Juice Increases Felodipine Oral Availability in Humans by Decreasing Intestinal CYP3A Protein Expression. J Clin Invest. 1997; 99(19): 2545-2553.

Thursday’s lecture 3/1/07

Terfenadine Second-generation H1-receptor antagonist Rapidly and almost completely metabolized by CYP3A4 Active metabolite Cardiotoxic drug-drug interactions w/ erythromycin and ketoconazole Cardiotoxic effect: repolarization abnormalities  torsades de pointes VTach Benton, et al. Grapefruit juice alters terfenadine pharmacokinets, resulting in prolonged repolarization on the electrocardiogram. Clin Pharmacol Ther. 1996; 59: 383-8.

PK study: Terfenadine & Grapefruit juice Study: Is bioavailability of terfenadine enhanced by GFJ? Does timing of terfenadine dose and administration of GFJ matter? Benton, et al. Grapefruit juice alters terfenadine pharmacokinets, resulting in prolonged repolarization on the electrocardiogram. Clin Pharmacol Ther. 1996; 59: 383-8.

PK study: Terfenadine & Grapefruit juice Primary endpoints: QT prolongation, AUC, Cmax, Tmax 60 mg terfenadine bid x 7d + 240 mL GFJ w/ terfenadine x 7d OR + 240 mL GFJ 2 h after terfenadine dose x 7 d EKG and plasma level on day 7 and day 14

PK study: Terfenadine & Grapefruit juice 12 healthy people, 60 mg terfenadine q12h. Randomized parallel design A: Simultaneous GFJ administration B: GFJ 2 hours after terfenadine Benton, et al. Grapefruit juice alters terfenadine pharmacokinetics, resulting in prolonged repolarization on the electrocardiogram. Clin Pharmacol Ther. 1996; 59: 383-8.

PD: Terfenadine & Grapefruit juice Simultaneous group: QTC interval is greater at every time point over the dosing interval. After GFJ admin, QTc increased from 420 to 434 Delayed group, NS changes with or w/o GFJ A: Simultaneous GFJ administration B: GFJ 2 hours after terfenadine Benton, et al. Grapefruit juice alters terfenadine pharmacokinetics, resulting in prolonged repolarization on the electrocardiogram. Clin Pharmacol Ther. 1996; 59: 383-8.

Benton, et al. Grapefruit juice alters terfenadine pharmacokinetics, resulting in prolonged repolarization on the electrocardiogram. Clin Pharmacol Ther. 1996; 59: 383-8.

PK study: Terfenadine & GFJ conclusions PK interaction: Increases terfenadine concentration in some subjects Effect more pronounced when administered together Delayed effect likely d/t rapid absorption of terfenadine Interaction occurs in gut wall CYP3A enzymes ↑ concentration  increase in QTc interval on EKG Take home point: Be aware of interaction b/c every pt is different. May lead to arrhythmia. Benton, et al. Grapefruit juice alters terfenadine pharmacokinetics, resulting in prolonged repolarization on the electrocardiogram. Clin Pharmacol Ther. 1996; 59: 383-8.

Another study: Felodipine, water, grapefruit juice PK of IV and PO felodipine Grapefruit juice or water 15 min prior to dose of felodipine 10 mg ER tablet or 1.5 mg IV over 60 min Measured SBP, DBP, and HR 12 healthy men w/in 20% of IBW Lundahl J, Regardh CG, Edgar B, Johnsson G. Effects of grapefruit juice ingestion ± pharmacokinetics and haemodynamics of intravenously and orally administered felodipine in healthy men. Eur J Clin Pharmacol. 1997;52:139-145.

PK: Felodipine  IV felodipine w/ water IV felodipine w/ GFJ  PO felodipine w/ GFJ GFJ  no effect on IV route PO route: mean increase in Cmax 173%, and increase in AUC 72%. No Tmax or t1/2 change  PO felodipine w/ water Lundahl J, Regardh CG, Edgar B, Johnsson G. Effects of grapefruit juice ingestion ± pharmacokinetics and haemodynamics of intravenously and orally administered felodipine in healthy men. Eur J Clin Pharmacol. 1997;52:139-145.

PK data Lundahl J, Regardh CG, Edgar B, Johnsson G. Effects of grapefruit juice ingestion ± pharmacokinetics and haemodynamics of intravenously and orally administered felodipine in healthy men. Eur J Clin Pharmacol. 1997;52:139-145.

Hemodynamic effects in relation to PK Oral felodipine + GFJ  ↓ DBP (12 – 19 mmHg); ↓ HR Effects were similar for IV felodipine w/ water & GFJ Lundahl J, Regardh CG, Edgar B, Johnsson G. Effects of grapefruit juice ingestion ± pharmacokinetics and haemodynamics of intravenously and orally administered felodipine in healthy men. Eur J Clin Pharmacol. 1997;52:139-145.

Hemodynamic data

Study: Felodipine & GFJ conclusions Metabolism of felodipine occurred in gut wall Increased plasma concentrations w/ oral felodipine & GFJ  increase hemodynamic effects

Clinical Application GFJ: ↑ oral availability of commonly used medications Is the interaction significant?

Grapefruit juice & Seville Orange juice Furocoumarins Bergamottin (16 μM GFJ; 5 μM SOJ) 6’,7’-dihyroxybergamottin (10-60 (23) μM GFJ; 36 μM SOJ) Bergapten (31 μM SOJ only) Bergapten – less potent 6’7’ dihydroxybergamottin

Study: Seville Orange juice, GFJ, & felodipine Juice  equimolar concentration Single dose felodipine Seville orange juice Dilute GFJ Common orange juice  (-) control Hypothesis: furocoumarins are involved in the “grapefruit juice interaction” Equimolar concentrations of bergamottin and 6’,7’-dihydroxybergamottin 5 men, 5 women, 10 mg ER tablet felodipine. 8 oz or 240 mL juice Malhotra et al. Seville orange juice-felodipine interaction: Comparison with dilute grapefruit juice and involvement of furocoumarins. 2001; 69(1):14-23.

Conc vs. time - felodipine (A- Felodipine) Seville OJ: AUC increased 76%, Cmax increased 61% w/ GFJ: AUC increased 93% and Cmax increased 88% compared to control (OJ). Difference between GFJ and SOJ were NS. (B – Dehydrofelodipine) AUC increased ~30%, but not Cmax. Single, inactive primary metabolite, then secondary metabolite by CYP3A4 GFJ interaction decreased metabolite/parent AUC ratio  inhibition of the primary metabolic pathway. GFJ action through inhibition of CYP3A4 mediated first-pass metabolism in the small intestine. Malhotra et al. Seville orange juice-felodipine interaction: Comparison with dilute grapefruit juice and involvement of furocoumarins. 2001; 69(1):14-23.

PK data: felodipine PK data following a single dose of felodipine taken with 8 ounces SOJ, GFJ, or OJ Malhotra et al. Seville orange juice-felodipine interaction: Comparison with dilute grapefruit juice and involvement of furocoumarins. 2001; 69(1):14-23.

Study conclusions Sufficient bergamottin and 6’,7’-dihydroxybergamottin concentrations  drug-interaction More furocoumarins?  drug-interactions Sufficient conc. To produce in vivo inhibition of CYP3A4 and interaction with felodipine

Just in case… Cyclosporine: Edwards et al. 6’,7’-dihydroxybergamottin in grapefruit juice and Seville orange juice: Effects on cyclosporine disposition, enterocyte CYP3A4, and P-glycoprotein. Clin Pharmacol Ther 1999;65(3): 237-44. Pranidipine: Hashimoto et al. Interaction of citrus juices with pranidipine, a new 1,4-dihydropyridine calcium antagonist, in healthy subjects. Eur J Clin Pharmacol 1998;54:753-60. Celiprolol: Lilja JJ, Juntti-Patinen L, Neuvonen PJ. Orange juice substantially reduces the bioavailability of the β-adrenergic-blocking agent celiprolol. Clin Pharmacol Ther 2004;75(3):184-90. Fexofenadine: Dresser et al. Fruit juices inhibit organic anion transporting polypeptide-mediated drug uptake to decrease the oral availability of fexofenadine. Clin Pharmacol Ther 2002;71(1):11-20.

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St John’s Wort OTC: Treat anxiety, depression, sleep disorders Warning on antiretroviral drugs d/t decreasing drug concentration w/ St John’s wort

St John’s Wort Known CYP3A4 induction Reports of interactions with: Theophylline (CYP1A2) Amitriptyline ((CYP2D6, CYP1A2) Warfarin (CYP2C9) Digoxin (p-gp substrate) Wang et al. The effects of St John’s wort (Hypericum perforatum) on human cytochrome P450 activity. Clin Pharmacol Ther 2001;70(4):317-26.

PK study: St John’s wort & CYP Interaction at the level of CYP? Which CYPs are involved? Induction? Inhibition? Three part study (control, short-term dosing, long-term dosing) Wang et al. The effects of St John’s wort (Hypericum perforatum) on human cytochrome P450 activity. Clin Pharmacol Ther 2001;70(4):317-26.

Study drugs Tolbutamide (CYP2C9) Caffeine (CYP2A1) Dextromethorphan (CYP2D6) Oral midazolam (intestinal wall and hepatic CYP3A) IV midazolam (hepatic CYP3A) Wang et al. The effects of St John’s wort (Hypericum perforatum) on human cytochrome P450 activity. Clin Pharmacol Ther 2001;70(4):317-26.

PK study: St John’s wort & CYP Control: tolbutamide, caffeine, DM po, and versed IV, then oral versed 24 h later Short-term: 900mg St John’s wort then same as above, + 2nd dose of 900mg then St John’s wort x 14-15 additional days Long-term: 900mg St John’s wort then same as above, + 2nd dose of 900mg

PK study: St John’s wort & CYP IV oral Short-term: no change Long-term: 50% reduction in oral AUC and Cmax □ before St John’s wort ○ after St John’s wort (short-term phase) ♦ after St John’s wort (long-term phase)

PK data Short-term: no change Long-term: 50% reduction in oral AUC and Cmax

Study drugs Tolbutamide (CYP2C9) Caffeine (CYP2A1) Dextromethorphan (CYP2D6) Oral midazolam (intestinal wall and hepatic CYP3A) IV midazolam (hepatic CYP3A) Wang et al. The effects of St John’s wort (Hypericum perforatum) on human cytochrome P450 activity. Clin Pharmacol Ther 2001;70(4):317-26.

Other outcomes Oral caffeine – CYP1A2  NS Oral tolbutamide – CYP2C9  NS Oral DM – CYP2D6  NS Interaction = CYP3A4

Study conclusions Induction of CYP3A by St John’s wort Long-term use  ↓ efficacy of drugs metabolized by CYP3A Induction in intestinal wall. >40% of all Rx drugs are metabolized by CYP3A enzymes

Lycopene

Lycopene ~80% of dietary lycopene from tomatoes and tomato products Most abundant carotenoid in human plasma Evidence for beneficial effects  preventing prostate cancer Availability from tomatoes is improved with processing (puree > raw) Prevention of prostate cancer. More lycopene intake, decrease risk of developing cancer Cohn et al. Comparative multiple dose plasma kinetics of lycopene administered in tomato juice, tomato soup or lycopene tablets. Eur J Nutr 2004;43:304-12.

Lycopene study Lycopene depletion phase Each group ~20mg lycopene daily x 8d Three tx groups Juice Soup Tablet Cohn et al. Comparative multiple dose plasma kinetics of lycopene administered in tomato juice, tomato soup or lycopene tablets. Eur J Nutr 2004;43:304-12.

Lycopene study Cohn et al. Comparative multiple dose plasma kinetics of lycopene administered in tomato juice, tomato soup or lycopene tablets. Eur J Nutr 2004;43:304-12.

Lycopene concentration: juice vs. soup vs. tablet Cohn et al. Comparative multiple dose plasma kinetics of lycopene administered in tomato juice, tomato soup or lycopene tablets. Eur J Nutr 2004;43:304-12.

Conclusions Processing releases lycopene for absorption Also causes conversion to all-E-lycopene, the most stable configuration 8 days of tomato product double the average concentration from baseline