"One man's meat is another man's poison" - On the interaction between grapefruit and drugs

This is the 4553th article of Da Yi Xiao Hu

“Eating grapefruit in autumn and winter is better than eating meat.” Autumn is approaching, and it is the season for grapefruit to be on the market. Grapefruit, also known as pomelo, is native to the Americas and the South. It was introduced to China in the past 80 years and is cultivated in Fujian, Zhejiang, Guangdong, Guangxi, Hunan, Yunnan and other provinces [1]. Grapefruit is sour and sweet, rich in nutrients, and rich in vitamins, carotenoids, flavonoids, coumarins and other ingredients. It has antioxidant, anti-aging, and beauty-enhancing effects and is deeply loved by the public. However, for people who take medication, grapefruit is like a time bomb. If you are not careful, you will be "hit", causing food and drug interactions, which may even lead to death. Previously, a woman who took antihypertensive drugs suffered from hypotension shock after eating grapefruit, which endangered her life; there was also a case where a man who took lipid-lowering drugs suffered from "muscle dissolution" after eating grapefruit for 7 consecutive days. So is grapefruit really that scary? What other medications should we pay attention to?

The reason is that grapefruit contains furanocoumarins, an irreversible CYP3A4 inhibitor [2]. Many drugs work or become ineffective through the metabolism of this enzyme. If the enzyme is inhibited, the blood concentration of drugs that require the enzyme to metabolize will increase, resulting in several times the efficacy or adverse reactions. The effect of grapefruit on CYP3A4 can last for more than 24 hours, and a glass of juice (200-250mL) may produce an effect [3,4]. Therefore, when taking medication, you must pay attention to the drug instructions to see if there are any contraindications to taking grapefruit juice. If there is an interaction, it is recommended not to eat grapefruit 72 hours before and after taking the medication.

The following are common drugs that interact with grapefruit. Different font colors represent the severity: red is contraindicated: it is forbidden to use them at the same time; orange is serious: it may be life-threatening, and medical intervention is required to reduce or avoid serious adverse reactions when they must be used at the same time; blue is moderate: it may potentially aggravate the patient's condition or require changes in treatment.

Note: Some of the drug interaction data comes from the Medication Assistant. If you are taking medication, please read the instructions carefully. If you are not sure whether you need to abstain from grapefruit, please consult your doctor or pharmacist.

References:

[1] Zhu Chunhua, Zhou Xianyan, Li Jinxue, Gao Junyan, Du Yuxia, Duo Jianzu, Yue Jianqiang. Research progress on the nutrition and health benefits of grapefruit fruit[J]. China Medical Herald, 2019, 16(15): 29-32.

[2]Fuhr LM, Marok FZ, Fuhr U, Selzer D, Lehr T. Physiologically Based Pharmacokinetic Modeling of Bergamottin and 6,7-Dihydroxybergamottin to Describe CYP3A4 Mediated Grapefruit-Drug Interactions. Clin Pharmacol Ther. 2023 Aug;114(2):470-482. doi: 10.1002/cpt.2968. Epub 2023 Jun 25. PMID: 37307228.

[3]Lundahl J , Reg?Rdh CG , Edgar B ,et al.Relationship between time of intake of grapefruit juice and its effect on pharmacokinetics and pharmacodynamics of felodipine in healthy subjects[J].European Journal of Clinical Pharmacology, 1995, 49(1-2):61-67.DOI:10.1007/BF00192360.

[4] Bailey DG , Dresser G , Anold JMO .Grapefruit-medication interactions: Forbidden fruit or avoidable consequences?[J].Canadian Medical Association Journal, 2012, 185(4).DOI:10.1503/cmaj.120951.

Author: Shanghai Sixth People's Hospital

Zhang Zhongqiu