Pharmacodynamics: Drug Action and Receptors, Slides of Pharmacology

Download Pharmacodynamics: Drug Action and Receptors and more Slides Pharmacology in PDF only on Docsity! PHARMACODYNAMICS I: DRUG ACTION & RECEPTORS ESAN OLABAYO DRUG ACTION DEFINITION Drug action refers to the mechanism by which the drug produces desirable or undesirable effects in the body DRUG ACTION TYPES OF DRUG ACTION • Stimulation • Depression • Irritation • Replacement • Cytotoxic DRUG ACTION TYPES OF DRUG ACTION • Stimulation • Involves the selective enhancement of specific activity done by a specialized cell • E.g. Adrenaline in Cardiac arrest DRUG ACTION TYPES OF DRUG ACTION • Replacement • Involves replacement of deficient endogenous substances • E.g. Insulin in Diabetes Mellitus DRUG ACTION TYPES OF DRUG ACTION • Cytotoxic action • Involves the selective destruction of cells, usually neoplasm or microbes, without significantly affecting other cells • E.g. Cyclophosphamide for cancer DRUG ACTION MECHANISM OF THE DRUG ACTION • Physical • Chemical • Biochemical DRUG ACTION MECHANISM OF THE DRUG ACTION • Biochemical mechanism (RICE) • Receptors • Albuterol for Asthma • Ion channels • Lidocaine for Local anesthesia • Carrier • Omeprazole for Peptic Ulcer Disease • Enzymes • Captopril for Hypertension RECEPTORS DEFINTION • Are regulatory macromolecule protein that are found either on the surface of or within the cells • They are the target sites for most drug action in the body RECEPTORS TYPES OF RECEPTORS • Ligand gated channel receptors • G-protein coupled receptors • Enzyme linked receptors • Intracellular receptors RECEPTORS TYPES OF RECEPTORS • G-protein coupled receptors • Location: Membrane • Effectors: Channel or Enzymes • Coupling: G-protein • Examples: Muscarinic receptors • Drugs: Atropine • Structure: Monomeric or Dimeric structure comprising seven transmembrane helices. G PROTEIN EFFECTOR SECONDARY MESSANGER GS ADENYLYL CYCLASE cAMP GI ADENYLYL CYCLASE cAMP Gq PHOSPHOLIPASE C IP3 DAG Go Ca2++ CHANNEL - RECEPTORS TYPES OF RECEPTORS • Enzyme linked receptors • Location: Membrane • Effectors: Enzyme • Coupling: Direct • Examples: Insulin receptors • Drugs: Insulin • Structure: Single Transmembrane Helix linking extracellular receptor domain to intracellular kinase domain RECEPTORS DRUG RECEPTOR RELATIONSHIP • Affinity  Propensity of a drug to bind with a given receptor • Intrinsic activity  Capacity of a drug to induce functional change in a given receptor in a way that produces a biological response RECEPTORS DRUG RECEPTOR OUTCOME •Full agonist •Partial agonist •Inverse agonist •Antagonist 100 5 Full Agonist ® 80 Ss a = 3 = 60 5 rR Partial Agonist o oe © 40- 8 & — Antagonist ao 20 Basal Activity o- 1 I 1 Inverse Agonist Drug Concentration