Pharmacology I receptor

RECEPTOR,AFFINITY,EFFICACY,AGONIST,ANTAGONIST,INVERSE & PARTIAL AGONIST.

1. RECEPTOR & LIGANDS PRESENTED BY PHARMACOLOGY-I HEENA PARVEEN ASST.PROFESSOR . MRCP.

2. RECEPTOR Receptors are specific protein macromolecules in C.M, Cytosol,Nucleus . Many drugs(ligands) bind to ( i ) Receptors for endogenous substances, (ii) Enzymes, (iii) Other constituents,which serves as Receptors for drugs. Ligand binding alters Enzyme activity, Changes permeability to ions, Confirmational changes in the genetic material of nucleus..

3. LOCK & KEY MODEL

4. Receptor serves as a dual function: It acts as recognition molecule for specific ligands It initiates biochemical reactions which transmit the signal from ligand to proteins in the cell membrane & within the cell. Biologically a receptor is inactive till ligand binds to it, only then it gets activated & triggers the post-receptor events . Interaction between ligand & Receptor are characterized by principal parametres : SELECTIVITY & AFFINITY

5. Affinity -A measure of the strength of binding b/w Drug & Receptor. Selectivity- depends on the physico -chemical properties of drug & receptor. Efficacy- Ability of a drug to elicit a response after its interaction with the receptor is also termed as Intrinsic activity. AGONIST- A drug which initiates pharmacological action after binding to the recptors .A drug with HIGH AFFINITY & INTRINSIC ACTIVITY. ANTAGONIST- A drug which also binds to the receptors but doesn’t elicit a pharmacological action ,it causes Receptor blockade. A drug with HIGH AFFINITY & POOR INTRINSIC ACTIVITY.

6. PARTIAL AGONIST A drug with affinity equal to and less than that of agonist but less intrinsic activity. This drug,no matter how high its conc , will not produce full response which the tissue is capable of.

7. INVERSE AGONIST After combination with a receptor ,a drug may produce actions opposite to those produced by a pure agonist.

8. THANK YOU