Pharmacodynamics

Pharmacodynamics PD

TRFarmakodinamik

The branch of pharmacology that studies what a drug does to the body: the biochemical and physiological effects of drugs, their mechanisms of action and the relationship between drug concentration and response.

Formula

E = Emax × C / (EC50 + C)

In depth

Pharmacodynamics covers drug–target interactions (receptors, enzymes, ion channels, transporters), the signal transduction that follows and the quantitative relationship between concentration and response. This relationship is usually described by the Emax (Hill) model, in which effect (E) depends on concentration (C), the maximal effect (Emax) and the concentration producing half-maximal effect (EC50). Core concepts include affinity, efficacy, potency, selectivity, agonism and antagonism.

Together with pharmacokinetics (what the body does to the drug), pharmacodynamics explains the intensity and time course of drug effects; PK/PD modelling links dose, concentration and effect and underpins dose selection, therapeutic windows and the interpretation of tolerance.

Clinical pearl

Pharmacodynamic differences such as receptor sensitivity, disease state and age explain why patients with similar plasma concentrations can respond differently; older adults, for example, are often more sensitive to benzodiazepines and opioids.

TRIn Turkish

Farmakodinamik

İlacın vücuda ne yaptığını, yani ilaçların biyokimyasal ve fizyolojik etkilerini, etki mekanizmalarını ve ilaç konsantrasyonu ile yanıt arasındaki ilişkiyi inceleyen farmakoloji dalıdır.

Farmakodinamik; ilaç–hedef etkileşimlerini (reseptörler, enzimler, iyon kanalları, taşıyıcılar), bunu izleyen sinyal iletimini ve konsantrasyon ile yanıt arasındaki nicel ilişkiyi kapsar. Bu ilişki genellikle etkinin (E) konsantrasyona (C), maksimal etkiye (Emax) ve yarı maksimal etki oluşturan konsantrasyona (EC50) bağlı olarak tanımlandığı Emax (Hill) modeliyle ifade edilir. Temel kavramlar afinite, etkinlik, potens, seçicilik, agonizma ve antagonizmadır.

Farmakokinetikle (vücudun ilaca ne yaptığı) birlikte ilaç etkisinin şiddetini ve zaman seyrini açıklar; FK/FD modellemesi doz, konsantrasyon ve etkiyi birbirine bağlayarak doz seçiminin, terapötik pencerenin ve toleransın yorumlanmasının temelini oluşturur.

Reseptör duyarlılığı, hastalık durumu ve yaş gibi farmakodinamik farklılıklar, benzer plazma konsantrasyonlarına sahip hastaların neden farklı yanıt verebildiğini açıklar; örneğin yaşlılar benzodiazepinlere ve opioidlere çoğu zaman daha duyarlıdır.

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

Read next

PharmacokineticsFarmakokinetik

The branch of pharmacology that describes what the body does to a drug: the time course of its absorption, distribution, metabolism and excretion (ADME) and the resulting concentrations in plasma and tissues.

 Mechanism of ActionEtki Mekanizması

The specific biochemical interaction through which a drug produces its pharmacological effect, usually binding to a defined molecular target such as a receptor, enzyme, ion channel or transporter.

 ReceptorReseptör

A macromolecule, usually a protein, to which a drug or endogenous ligand binds specifically and thereby initiates a change in cell function that produces a biological response.

 Dose–Response CurveDoz–Yanıt Eğrisi

A graph relating the dose or concentration of a drug to the magnitude of its effect (graded curve) or to the proportion of a population showing a specified all-or-none response (quantal curve).

 EfficacyEtkinlik

The capacity of a drug to produce a response once bound to its receptor; in clinical terms, the maximal effect (Emax) a drug can produce, however much the dose is increased.

 PotencyPotens

The amount or concentration of a drug needed to produce an effect of a given intensity, usually expressed as the EC50 or ED50; the lower the value, the more potent the drug.