grapefruit
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Pharmacokinetics
- inhibits cyt P450 3A4 & P-glycoprotein in the GI tract
- hepatic cyt P450 3A4 not affected[7]
- may take 3 days for cyt P450 3A4 enzyme activity to recover
Adverse effects
- high citrus fruit consumption (orange juice & grapefruit) associated with increased risk for cutaneous melanoma (RR=1.36)[10]*
* association possibly due to psoralen in citrus fruits; psoralen has photocarcinogenic properties in animals[10]
Drug interactions
- grapefruit inhibits cyt P450 3A4, thus inhibits metabolism of:
- HMG CoA reductase inhibitors:
- atorvastatin (up to 25% increase)
- lovastatin (up to 300% or more increase)
- simvistatin (up to 300% or more increase)
- pravastatin (Pravachol) & fluvastatin (Lescol) are NOT metabolized by cyt P450 3A4, thus are unaffected by consumption of grapefruit
- Ca+2 channel blockers
- benzodiazepines
- antiretroviral agents
- amprenavir (probably not significant)
- saquinavir
- indinavir
- immunosuppressants
- anticonvulsants
- carbamzepine
- phenytoin
- antiarrythic agents
- amiodarone
- carvediolol
- digoxin
- quinidine
- antibiotics
- clarithromycin
- erythromycin
- telithromycin (no effect)
- itraconazole
- antineoplastic agents
- ARBs
- antipsychotics
- antidepressants
- buspirone
- clomipramine
- fluvoxamine
- sertaline
- endocrine agents
- antihistamines
- caffeine
- cisapride
- methdone
- scopalamine
- sildenafil
- theophylline
- cilostazol
- warfarin
- HMG CoA reductase inhibitors:
Mechanism of action
- inhibits CYP3A4 & P-glycoprotein in the GI tract[5]
- increases absorption of pharmaceuticals metabolized by cyt P450 3A4
- one 8 oz glass of grapefruit juice or 1 grapefruit can cause significant drug interactions[5]
- may reduce insulin levels & promote weight reduction by diminishing appetite[6]
More general terms
Additional terms
References
- ↑ Kaiser Permanente Northern California Regional Memo, 12/99
- ↑ http://www.powernetdesign.com/grapefrut/
- ↑ Prescriber's Letter 6(10):55, Oct, 1999
- ↑ Prescriber's Letter 13(3): 2006 Cytochrome P450 drug interactions Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=220233&pb=PRL (subscription needed) http://www.prescribersletter.com
- ↑ 5.0 5.1 5.2 Prescriber's Letter 9(9):54, Sept, 2002
- ↑ 6.0 6.1 CBS Healthwatch from Netscape (Feb 9, 2004) research from Fujioka K. Scripps Metabolic Research Center, Scripps Clinic cited
- ↑ 7.0 7.1 Prescriber's Letter 14(2): 2007 Potentional drug interactions with grapefruit Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=230204&pb=PRL (subscription needed) http://www.prescribersletter.com
- ↑ 8.0 8.1 Prescriber's Letter 18(3): 2011 CHART: Potential Drug Interactions with Grapefruit Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=270307&pb=PRL (subscription needed) http://www.prescribersletter.com
- ↑ Prescriber's Letter 20(1): 2013 CHART: Potential Drug Interactions with Grapefruit COMMENTARY: OATP Fruit Juice Drug Interactions Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=290121&pb=PRL (subscription needed) http://www.prescribersletter.com
- ↑ 10.0 10.1 10.2 Wu S, Han J, Feskanich D et al Citrus Consumption and Risk of Cutaneous Malignant Melanoma. JCO published online on June 29, 2015 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/26124488 <Internet> http://jco.ascopubs.org/content/early/2015/06/24/JCO.2014.57.4111.abstract
Berwick M Dietary Advice for Melanoma: Not Ready for Prime Time. JCO published online on June 29, 2015 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/26124491 <Internet> http://jco.ascopubs.org/content/early/2015/06/24/JCO.2015.61.8116.full