Receptors, Agonists, Antagonists

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Neil Credo, Victor Quiniano, Fall 2008

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Presentation Transcript

Receptors, Agonists and Antagonists : 

Receptors, Agonists and Antagonists Presented by: OUCN Fall 2008 TEAM QC Neil Credo Victor Quiniano

RECEPTORS : 

RECEPTORS Definition Receptors are special “Chemicals” in the body that most drugs interact with to produce effects.

Receptors : 

Receptors A receptor is a functional macromolecule in a cell to which a drug binds to produce its effect. The term is generally reserved for what is arguably the most important group of macromolecules through which drugs act: the body’s own receptors for hormones, neurotransmitters, and other regulatory molecules.

Formula for Receptors : 

Formula for Receptors D = Drug R = Receptor D + R ≒ D-R Complex ⇒ RESPONSE Binding of a drug to its receptor is usually REVERSIBLE.

Receptors : 

Receptors A receptor is analogous to a light switch in that it has two configurations: “ON” and “OFF” A receptor must be “ON” to influence cellular function

Four Primary Receptor Families : 

Four Primary Receptor Families Cell membrane-embedded enzymes Ligand-gated ion channels G protein-coupled receptor systems Transcription Factors

Agonists : 

Agonists Definition Agonists are molecules that activate receptors.

Agonists : 

Agonists An agonist is a drug that has both affinity and high intrinsic activity. AFFINITY allows the agonist to bind to receptors. INTRINSIC ACTIVITY allows the bound agonist to “activate” or “turn on “ receptor function.

AgonistAffinity and Intrinsic Activity : 

AgonistAffinity and Intrinsic Activity

Agonists : 

Agonists Many therapeutic agents produce their effects by functioning as agonists. Dobutamine for example, is a drug that mimics the action of NE (norepinephrine) at the receptors on the heart, thereby causing heart rate and force of contraction to increase.

Agonists : 

Agonists

Antagonist : 

Antagonist Definition An antagonist is a drug with affinity for a receptor but with no intrinsic activity. Affinity allows the antagonist to bind to receptors, but lack of intrinsic activity prevents the bound antagonist from causing receptor activation.

Antagonist : 

Antagonist Although antagonists do not cause receptor activation, they most certainly do produce pharmacologic effects. They prevent the activation of receptors by agonists.

Antagonist : 

Antagonist Antagonists can produce beneficial effects by blocking the action of drugs – employed most commonly in the treatment of overdose. Response to an antagonist is determined by how much agonist is present. If there is no agonist present, administration of an antagonist will have no observable effect.

Antagonist : 

Antagonist

Receptors, Agonists and Antagonists : 

Receptors, Agonists and Antagonists Theories of Drug-Receptor Interaction Simple Occupancy Theory Intensity of the response to a drug is proportional to the number of receptors occupied by that drug. A maximal response will occur when all available receptors have been occupied. The Modified Occupancy Theory The ability to bind to the receptor The ability to influence receptor function once binding has taken place.

References : 

References Lehne, R. (2007). Pharmacology for Nursing Care (6th Ed.). St. Louis, Saunders Elsevier. http://images.search.yahoo.com/images/view?back=http