Grapefruit drug interactions5/6/2023 One study showed that drinking a glass of grapefruit juice with simvastatin or lovastatin increased blood levels of these statins by 260% ( 5).Īlternatives: Pravastatin (Pravachol), rosuvastatin (Crestor), and fluvastatin (Lescol) do not interact with grapefruit ( 1). Grapefruit increases the blood levels of three common statins substantially, increasing the risk of rhabdomyolysis ( 4): This leads to muscle weakness, pain, and occasionally kidney damage ( 3). Statins can cause rhabdomyolysis, or the breakdown of muscle tissue. This improves the profile of lipoproteins in the blood and decreases deaths from heart disease in patients at risk of it ( 2). ![]() Statins work by limiting the natural production of cholesterol. Some cholesterol medications called statins are affected by grapefruit. With that in mind, here is detailed information about 32 common medications that may interact with grapefruit, categorized by use. For a small number of drugs, grapefruit’s effects can be serious. Taking your medication a few hours apart from consuming it isn’t long enough. Grapefruit’s ability to affect medication lasts for 1–3 days. ![]() One whole grapefruit or one glass of grapefruit juice is enough to alter how these medications affect you. There are three things to know to understand if and how you can safely consume grapefruit with these medications. In fact, studies show that they increase the blood levels of over 85 medications ( 1).īy slowing the way in which CYPs normally break down medications in your gut and liver, grapefruit can increase the side effects of these drugs ( 1). Grapefruit and a few of its close relatives, such as Seville oranges, tangelos, pomelos, and Minneolas, contain a class of chemicals called furanocoumarins.įuranocoumarins disrupt the normal function of CYPs. Grapefruit juice also alters the presystemic metabolism of terfenadine, to a degree similar to the changes that occur with itraconazole and erythromycin, leading to the accumulation of a greater amount of terfenadine and QTc prolongation (presumably increasing the risk of torsades de pointes).Medications are processed in your liver and small intestine by a specialized group of proteins called cytochrome P450 (CYPs).ĬYPs break down medications, reducing the blood levels of many of them. The effects of a variety of CYP3A4 inhibitors (erythromycin, ketoconazole) on causing torsades de pointes by increasing the circulating levels of terfenadine are well recognized. The parent compound has considerable potentiation to QTc prolongation via inhibition of the delayed rectifier potassium channel in the cardiomyocyte (whereas the metabolites do not), leading to an increased risk of ventricular tachycardia and torsades de pointes. It undergoes extensive presystemic first-phase metabolism in the gut wall by CYP enzymes to active carboxylic metabolites, including fexofenadine, to the extent that normally terfenadine levels are not measurable in the plasma. The nonsedating H 1-receptor antagonist terfenadine was widely used in the treatment of hay fever and other allergic conditions. ![]() CYP3A4 = cytochrome P-450 3A4 HIV = human immunodeficiency virus: HMG-CoA = 3-hydroxy-3-methylglularyl coenzyme A. “Yes” and “No” indicate expected findings based on available data. “Yes” and “No” indicate published evidence of the presence or absence of an interaction with grapefruit juice. AUC ( area under the plasma concentration–time curve), CYP ( cytochrome P-450), HMG-CoA ( 3-hydroxy-3-methyl glutaryl coenzyme A), Pgp ( P-glycoprotein) This review discusses the proposed mechanisms of action and the medications involved in drug–grapefruit juice interactions and addresses the clinical implications of these interactions. The P-glycoprotein pump, located in the brush border of the intestinal wall, also transports many cytochrome P-450 3A4 substrates, and this transporter also may be affected by grapefruit juice. In the case of some drugs, these increased drug concentrations have been associated with an increased frequency of dose-dependent adverse effects. Most notable are its effects on cyclosporine, some 1,4-dihydropyridine calcium antagonists, and some 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors. Through the inhibition of this enzyme system, grapefruit juice interacts with a variety of medications, leading to elevation of their serum concentrations. Grapefruit juice, a beverage consumed in large quantities by the general population, is an inhibitor of the intestinal cytochrome P-450 3A4 system, which is responsible for the first-pass metabolism of many medications.
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