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Interactions between grapefruit juice and cardiovascular drugs
David G Bailey1, George K Dresser
1Department of Medicine and Lawson Health Research Institute, London Health Sciences Centre, London, Ontario, Canada. david.bailey@lhsc.on.ca
Summary
Grapefruit juice significantly impacts drug absorption and effectiveness by affecting drug-metabolizing enzymes and transporters. Avoiding grapefruit juice during medication use is crucial to prevent potentially dangerous drug interactions and toxicity, especially in the elderly.
Area of Science:
- Pharmacology
- Drug Metabolism
- Drug Interactions
Background:
- Grapefruit juice is known to affect oral drug pharmacokinetics through various mechanisms.
- Key mechanisms include irreversible inactivation of intestinal cytochrome P450 (CYP) 3A4 and inhibition of P-glycoprotein (P-gp) efflux transport.
- Recent findings also suggest inhibition of organic anion transporting polypeptides (OATPs) by grapefruit juice.
Purpose of the Study:
- To elucidate the pharmacokinetic alterations induced by grapefruit juice.
- To identify specific drug classes and individual medications that interact with grapefruit juice.
- To highlight the clinical implications and risks associated with these interactions.
Main Methods:
- Review of existing literature on grapefruit juice-drug interactions.
- Analysis of proposed mechanisms including enzyme inhibition (CYP3A4) and transporter modulation (P-gp, OATPs).
- Identification of drugs with potential interactions based on their metabolic pathways and transport mechanisms.
Main Results:
- Grapefruit juice increases oral drug bioavailability by reducing presystemic metabolism (CYP3A4) and/or efflux transport (P-gp).
- Conversely, inhibition of OATPs by grapefruit juice can decrease oral drug bioavailability.
- Numerous cardiovascular drugs, statins, antihypertensives, antidiabetics, and other medications exhibit significant interactions with grapefruit juice, leading to increased toxicity or reduced efficacy.
Conclusions:
- Grapefruit juice interactions can lead to serious adverse events such as rhabdomyolysis, excessive vasodilation, hypoglycemia, and enhanced drug toxicity.
- Drugs with low oral bioavailability and potential for serious overdose toxicity necessitate complete avoidance of grapefruit juice.
- The elderly population, often on multiple medications, is particularly vulnerable to these interactions.