Drug Metabolism & Transporters

Enzyme Induction

TREnzim İndüksiyonu
Also known as:Metabolic induction

An increase in the amount and activity of a drug-metabolizing enzyme or transporter, usually through enhanced gene transcription, caused by repeated exposure to a drug or other xenobiotic.

In depth

Most inducers act through nuclear receptors: the pregnane X receptor (PXR) and constitutive androstane receptor (CAR) up-regulate CYP3A4, CYP2B6, CYP2C enzymes, UGTs and P-glycoprotein, whereas the aryl hydrocarbon receptor (AhR) mediates CYP1A2 induction. Classic inducers are rifampicin, carbamazepine, phenytoin, phenobarbital and St. John's wort; polycyclic aromatic hydrocarbons in tobacco smoke induce CYP1A2.

Because new enzyme must be synthesized, induction develops gradually, often reaching its maximum after one to two weeks, and wanes over a similar period after the inducer is stopped. It lowers exposure to victim drugs and can increase formation of active or toxic metabolites.

Clinical pearl

When an inducer is stopped, concentrations of co-administered substrates rise over the following days to weeks; for example, smoking cessation can increase clozapine and olanzapine levels, and dose reduction may be needed.

Example drugs

Rifampicin Carbamazepine Phenytoin Phenobarbital
TRIn Turkish

Enzim İndüksiyonu

Bir ilaca veya başka bir ksenobiyotiğe tekrarlanan maruziyet sonucunda, genellikle gen transkripsiyonunun artmasıyla, ilaç metabolize eden bir enzimin ya da taşıyıcının miktarının ve aktivitesinin yükselmesidir.

İndükleyicilerin çoğu nükleer reseptörler aracılığıyla etki eder: pregnan X reseptörü (PXR) ve konstitütif androstan reseptörü (CAR), CYP3A4, CYP2B6, CYP2C enzimleri, UGT'ler ve P-glikoprotein ekspresyonunu artırırken aril hidrokarbon reseptörü (AhR) CYP1A2 indüksiyonuna aracılık eder. Klasik indükleyiciler rifampisin, karbamazepin, fenitoin, fenobarbital ve sarı kantarondur; sigara dumanındaki polisiklik aromatik hidrokarbonlar CYP1A2'yi indükler.

Yeni enzim sentezlenmesi gerektiğinden indüksiyon kademeli olarak gelişir, çoğunlukla bir-iki haftada en yüksek düzeye ulaşır ve indükleyici kesildikten sonra benzer bir sürede geriler. Etkilenen ilaçlara maruziyeti azaltır; aktif veya toksik metabolitlerin oluşumunu ise artırabilir.

İndükleyici kesildiğinde birlikte kullanılan substratların konsantrasyonları sonraki günler ve haftalar içinde yükselir; örneğin sigarayı bırakma klozapin ve olanzapin düzeylerini artırabilir ve doz azaltımı gerekebilir.

Diğer adları:Enzim indüklenmesi
Updated 24.09.2026 1 views Educational reference — verify against current sources before clinical use.

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AutoinductionOtoindüksiyon

Induction by a drug of the enzymes responsible for its own metabolism, so that its clearance increases and its concentrations fall over time during continued dosing at the same dose.

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