Pharmacokinetics

Elimination Rate Constant ke

TREliminasyon Hız Sabiti
Also known as:Ke · Kel · elimination constant

A first-order rate constant (Ke or Kel) that quantifies the fraction of drug eliminated from the body per unit time, used to calculate half-life.

Formula

ke = CL / Vd ke = 0.693 / t½ ke = ln(C1 / C2) / (t2 − t1) C = C0 × exp(−ke × t)

In depth

In a one-compartment model, ke equals clearance divided by volume of distribution and is the negative slope of the natural-log concentration–time line; for multi-compartment drugs the terminal constant is written λz or β. It can be estimated from two concentrations, C1 and C2, measured at times t1 and t2 during the elimination phase.

ke is used to calculate half-life, to predict the concentration at any time t after a dose from the initial concentration C0, and to derive accumulation ratios and appropriate dosing intervals.

Clinical pearl

In aminoglycoside and vancomycin monitoring, a patient-specific ke estimated from two post-dose levels is used to individualise the dose and dosing interval.

Example drugs

Gentamicin Vancomycin
TRIn Turkish

Eliminasyon Hız Sabiti

Vücuttan birim zamanda elimine edilen ilaç fraksiyonunu ölçen birinci derece hız sabiti (Ke veya Kel); yarı ömür hesaplamasında kullanılır.

Tek kompartmanlı modelde ke, klirensin dağılım hacmine bölümüne eşittir ve doğal logaritmik konsantrasyon–zaman doğrusunun negatif eğimidir; çok kompartmanlı ilaçlarda terminal sabit λz veya β ile gösterilir. Eliminasyon fazında t1 ve t2 zamanlarında ölçülen iki konsantrasyondan (C1 ve C2) hesaplanabilir.

ke; yarılanma ömrünü hesaplamak, başlangıç konsantrasyonundan (C0) yola çıkarak dozdan sonraki herhangi bir t anındaki konsantrasyonu öngörmek ve birikim oranları ile uygun doz aralıklarını belirlemek için kullanılır.

Aminoglikozit ve vankomisin izleminde, dozdan sonra alınan iki düzeyden hesaplanan hastaya özgü ke değeri, doz ve doz aralığının bireyselleştirilmesinde kullanılır.

Diğer adları:Ke · Kel · eliminasyon sabiti
Updated 24.09.2026 40 views Educational reference — verify against current sources before clinical use.

Read next

Elimination Half-LifeEliminasyon Yarı Ömrü

The time required for the plasma concentration of a drug to decrease by 50% during the elimination phase, reflecting how long the drug remains active in the body.

 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.

 Volume of DistributionSanal Dağılım Hacmi

A theoretical volume that describes the extent to which a drug is distributed throughout the body tissues relative to the plasma, indicating how much the drug leaves the bloodstream to enter tissues.

 First-Order KineticsBirinci Derece Kinetik

A pharmacokinetic process where the rate of drug elimination (or absorption) is proportional to the drug's concentration, leading to exponential decline over time.

 Absorption Rate ConstantAbsorpsiyon Hız Sabiti

A first-order rate constant (Ka) that describes the rate at which a drug is absorbed from the site of administration into the systemic circulation.

 Therapeutic Drug MonitoringTerapötik İlaç İzlemi

The measurement of drug concentrations in blood at defined times, interpreted in the clinical context, to individualise dosing so as to maximise efficacy and minimise toxicity.