BASIC PRINCIPAL PART III IV

Pharmacodynamics

The study of the effects and mechanisms of action of drugs on biological systems, including the relationship between drug concentration and drug effect.

Dose-Response Curve

A graphical representation that plots the relationship between the dose of a drug and the magnitude of its effect.

Affinity

A measure of how tightly a drug binds to its receptor.

Potency

The amount of drug needed to produce a given effect.

Efficacy

The maximum effect that a drug can produce, regardless of the dose.

Full Agonist

A drug that binds to a receptor and produces the maximum response.

Partial Agonist

A drug that binds to a receptor but produces a less than maximum response.

EC50

The concentration of a drug that produces 50% of its maximum effect.

Antagonists

Drugs that bind to receptors but do not activate them, reducing the effects of agonists.

Competitive Antagonist

An antagonist that competes with an agonist for binding to the same receptor.

Irreversible Antagonist

An antagonist that permanently binds to a receptor, preventing activation by agonists.

Idiosyncratic Drug Response

An unusual or unexpected reaction to a drug that is specific to an individual.

Therapeutic Index (TI)

The ratio between the toxic and effective doses of a drug, indicating its safety margin.

Bioavailability

The proportion of a drug that enters circulation when introduced into the body and is available for action.

First-Pass Effect

A phenomenon where the concentration of a drug is significantly reduced before it reaches systemic circulation.

Apparent Volume of Distribution (Vd)

A pharmacokinetic parameter that describes the distribution of a drug within the body relative to the plasma concentration.