Pharmacokinetics

Renal Clearance CLR

TRRenal Klirens

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

Formula

CLR = (U × V) / P CLR = Ae / AUC CLR = fe × CL

In depth

Renal clearance is calculated as the urinary excretion rate (urine drug concentration U × urine flow rate V) divided by the plasma concentration P, or as the amount excreted unchanged in urine (Ae) divided by plasma AUC. It reflects glomerular filtration of unbound drug, active tubular secretion and passive tubular reabsorption.

A CLR higher than the filtration clearance (fu × GFR) indicates net secretion; a lower value indicates net reabsorption. CLR generally falls in proportion to creatinine clearance, so drugs with a large fraction excreted unchanged (fe), such as aminoglycosides, vancomycin, lithium and many β-lactams, need dose adjustment in renal impairment.

Clinical pearl

Drugs competing for tubular secretion interact: probenecid reduces the renal clearance of penicillins, and trimethoprim and cimetidine inhibit creatinine secretion, raising serum creatinine without a true fall in GFR.

Example drugs

Gentamicin Vancomycin Lithium carbonate Benzylpenicillin Probenecid
TRIn Turkish

Renal Klirens

Toplam klirensin böbreklere ait bileşenidir; birim zamanda idrarla atılım yoluyla ilaçtan arındırılan plazma hacmini ifade eder.

Renal klirens, idrarla atılım hızının (idrardaki ilaç konsantrasyonu U × idrar akım hızı V) plazma konsantrasyonuna (P) bölünmesiyle ya da idrarla değişmeden atılan miktarın (Ae) plazma AUC'sine bölünmesiyle hesaplanır. Bağlanmamış ilacın glomerüler filtrasyonunu, aktif tübüler sekresyonu ve pasif tübüler geri emilimi yansıtır.

CLR'nin filtrasyon klirensinden (fu × GFR) yüksek olması net sekresyonu, düşük olması net geri emilimi gösterir. CLR genellikle kreatinin klirensiyle orantılı olarak azalır; bu nedenle aminoglikozitler, vankomisin, lityum ve pek çok β-laktam gibi değişmeden atılan kesri (fe) büyük olan ilaçlarda böbrek yetmezliğinde doz ayarlaması gerekir.

Tübüler sekresyon için yarışan ilaçlar etkileşir: probenesid penisilinlerin renal klirensini azaltır; trimetoprim ve simetidin ise kreatinin sekresyonunu inhibe ederek GFR'de gerçek bir düşüş olmadan serum kreatininini yükseltir.

Diğer adları:Böbrek klirensi
Updated 24.09.2026 0 views Educational reference — verify against current sources before clinical use.

Read next

ClearanceKlirens

The rate at which a drug is removed from the body, primarily by the liver and kidneys, representing the volume of plasma cleared of the drug per unit time.

 Creatinine ClearanceKreatinin Klirensi

The volume of plasma cleared of creatinine per unit time, used as a clinical index of glomerular filtration rate and as the basis of most renal dosing recommendations.

 Renal Dose AdjustmentBöbrek Fonksiyonuna Göre Doz Ayarlaması

The modification of the dose or dosing interval of a drug that is cleared, or has active or toxic metabolites cleared, by the kidneys, to prevent accumulation and toxicity in renal impairment.

 ExcretionAtılım (Ekskresyon)

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.

 Unbound FractionSerbest Fraksiyon

The proportion of the total plasma drug concentration that is not bound to plasma proteins, expressed as a fraction (0–1) or percentage; only this free drug can cross membranes and interact with receptors.

 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.