Pharmacokinetics

Excretion

TRAtılım (Ekskresyon)
Also known as:Drug excretion

The removal of unchanged drug or its metabolites from the body, principally in urine and in bile (faeces), and to a lesser extent in exhaled air, sweat, saliva and breast milk.

In depth

Renal excretion is the net result of glomerular filtration of unbound drug, active tubular secretion by transporters such as OATs, OCTs and P-glycoprotein, and passive tubular reabsorption of lipid-soluble, un-ionised drug. Polar metabolites such as glucuronides are therefore excreted more readily than a lipophilic parent drug.

Biliary excretion favours polar molecules and conjugates of higher molecular weight, which may be hydrolysed by gut bacteria and reabsorbed (enterohepatic recirculation). Weakly basic, lipid-soluble, poorly protein-bound drugs pass more readily into breast milk, which is slightly more acidic than plasma.

Clinical pearl

Urinary antiseptics such as nitrofurantoin depend on renal excretion to reach effective urinary concentrations, so they lose efficacy, and accumulate systemically, when renal function is significantly impaired.

Example drugs

Nitrofurantoin
TRIn Turkish

Atılım (Ekskresyon)

Değişmemiş ilacın veya metabolitlerinin vücuttan başlıca idrar ve safra (dışkı) yoluyla, daha az ölçüde de solunum havası, ter, tükürük ve anne sütüyle uzaklaştırılmasıdır.

Böbrekten atılım; bağlanmamış ilacın glomerüler filtrasyonu, OAT, OCT ve P-glikoprotein gibi taşıyıcılar aracılığıyla aktif tübüler sekresyonu ve lipitte çözünen, iyonize olmamış ilacın pasif tübüler geri emiliminin net sonucudur. Bu nedenle glukuronitler gibi polar metabolitler lipofilik ana ilaca göre daha kolay atılır.

Safra ile atılım, molekül ağırlığı daha yüksek polar moleküller ve konjugatlar için belirgindir; bunlar bağırsak bakterilerince hidrolize edilip yeniden emilebilir (enterohepatik dolaşım). Zayıf bazik, lipitte çözünen ve proteinlere az bağlanan ilaçlar, plazmadan biraz daha asidik olan anne sütüne daha kolay geçer.

Nitrofurantoin gibi üriner antiseptikler etkili idrar konsantrasyonlarına böbrekten atılım yoluyla ulaşır; bu nedenle böbrek fonksiyonu belirgin biçimde bozulduğunda etkinliklerini yitirir ve sistemik olarak birikir.

Diğer adları:Ekskresyon · Boşaltım
Updated 24.09.2026 0 views Educational reference — verify against current sources before clinical use.

Read next

EliminationEliminasyon

The irreversible removal of a drug from the body, comprising its metabolism (biotransformation) to other chemical species and the excretion of unchanged drug or its metabolites.

 Renal ClearanceRenal Klirens

The component of total clearance attributable to the kidneys: the volume of plasma cleared of drug by urinary excretion per unit time.

 Enterohepatic RecirculationEnterohepatik Dolaşım

The cycle in which a drug or its conjugated metabolite is excreted in bile into the intestine, reabsorbed (after deconjugation, if conjugated) and returned to the liver via the portal circulation.

 Ion Trappingİyon Tuzaklanması

The accumulation of a weak acid or weak base on the side of a membrane where it is more ionised, because only the un-ionised form diffuses freely across lipid membranes.

 Drug Transporterİlaç Taşıyıcısı

A membrane protein that moves drugs across cell membranes, either into cells (uptake) or out of them (efflux), and thereby influences absorption, distribution and elimination.

 GlucuronidationGlukuronidasyon

A phase II conjugation reaction in which UDP-glucuronosyltransferases (UGTs) transfer glucuronic acid from UDP-glucuronic acid to a hydroxyl, carboxyl, amine or thiol group on a drug or metabolite.