Drug Interactions

Grapefruit Juice Interaction

TRGreyfurt Suyu Etkileşimi
Also known as:Grapefruit–drug interaction · Grapefruit effect

An interaction in which furanocoumarins in grapefruit juice irreversibly inhibit intestinal CYP3A4, increasing the oral bioavailability of drugs that undergo extensive first-pass metabolism by this enzyme.

In depth

Furanocoumarins such as bergamottin and 6′,7′-dihydroxybergamottin are mechanism-based inhibitors of enterocyte CYP3A4; hepatic CYP3A4 is affected little at usual intake. The effect follows a single glass and, because new enzyme must be synthesized, can last 24 hours or longer, so separating the drug from the juice does not reliably prevent it.

The interaction is greatest for oral CYP3A4 substrates with low bioavailability, such as simvastatin, lovastatin, felodipine and some other dihydropyridines, oral midazolam and several kinase inhibitors. Seville (bitter) oranges and pomelo contain similar compounds. Grapefruit juice can also inhibit intestinal OATP uptake and reduce absorption of some drugs, such as fexofenadine.

Clinical pearl

Patients taking simvastatin, felodipine or other sensitive CYP3A4 substrates should avoid grapefruit and its juice rather than simply space doses; switching to a drug not dependent on CYP3A4 (e.g. rosuvastatin, pravastatin) is an alternative.

Example drugs

Simvastatin Felodipine Midazolam ciclosporin Fexofenadine
TRIn Turkish

Greyfurt Suyu Etkileşimi

Greyfurt suyundaki furanokumarinlerin bağırsaktaki CYP3A4'ü geri dönüşümsüz olarak inhibe etmesi sonucu, bu enzimle yoğun ilk geçiş metabolizmasına uğrayan ilaçların oral biyoyararlanımının arttığı etkileşimdir.

Bergamottin ve 6′,7′-dihidroksibergamottin gibi furanokumarinler enterositlerdeki CYP3A4'ün mekanizma temelli inhibitörleridir; olağan tüketimde hepatik CYP3A4 az etkilenir. Etki tek bir bardaktan sonra ortaya çıkar ve yeni enzim sentezlenmesi gerektiğinden 24 saat veya daha uzun sürebilir; bu nedenle ilacın meyve suyundan ayrı zamanlarda alınması etkileşimi güvenilir biçimde önlemez.

Etkileşim, biyoyararlanımı düşük olan oral CYP3A4 substratlarında en belirgindir; simvastatin, lovastatin, felodipin ve diğer bazı dihidropiridinler, oral midazolam ve birçok kinaz inhibitörü buna örnektir. Turunç (Sevilla portakalı) ve pomelo da benzer bileşikler içerir. Greyfurt suyu bağırsaktaki OATP aracılı alımı da inhibe ederek feksofenadin gibi bazı ilaçların absorpsiyonunu azaltabilir.

Simvastatin, felodipin veya diğer duyarlı CYP3A4 substratlarını kullanan hastalar dozları ayırmakla yetinmeyip greyfurt ve suyundan kaçınmalıdır; CYP3A4'e bağımlı olmayan bir ilaca (ör. rosuvastatin, pravastatin) geçmek de bir seçenektir.

Diğer adları:Greyfurt–ilaç etkileşimi · Greyfurt etkisi
Updated 24.09.2026 0 views Educational reference — verify against current sources before clinical use.

Read next

CYP3A4CYP3A4

The most abundant cytochrome P450 isoform in the human liver and small-intestinal epithelium, responsible for the oxidative metabolism of a large proportion of clinically used drugs.

 Mechanism-Based InhibitionMekanizma Temelli İnhibisyon

Irreversible or quasi-irreversible enzyme inactivation in which the enzyme converts the inhibitor into a reactive intermediate that binds covalently or tightly to it, so activity returns only as new enzyme is synthesized.

 Drug–Food Interactionİlaç–Besin Etkileşimi

An alteration of a drug's absorption, disposition or effect by food, specific food constituents or beverages, or an alteration of nutritional status by a drug.

 First-Pass Effectİlk Geçiş Etkisi

The metabolism of a drug in the liver (or gut wall) before it reaches systemic circulation, often reducing the bioavailability of orally administered drugs.

 BioavailabilityBiyoyararlanım

The fraction of an administered dose that reaches the systemic circulation unchanged, and the rate at which it does so; by definition, bioavailability is 1 (100%) for an intravenous dose.

 Enzyme InhibitionEnzim İnhibisyonu

A reduction in the activity of a drug-metabolizing enzyme by a co-administered drug or other substance, which lowers the clearance of drugs dependent on that enzyme and raises their concentrations.