Agonist responses - = a ffi nity and e ffi cacy - Full agonist = - PowerPoint PPT Presentation

Agonist responses - = a ffi nity and e ffi cacy - Full agonist = can generate maximum response Spare receptors - - Partial agonist = cannot generate max - EC50 = concentration for 50% drug's maximum response One 2 One Medicine: Pre-clinical revision course

Agonist responses - = a ffi nity and e ffi cacy - Full agonist = can generate maximum response Spare receptors - - Partial agonist = cannot generate max - EC50 = concentration for 50% drug's maximum response One 2 One Medicine: Pre-clinical revision course

Spare receptors 100% Partial agonist 100% Response 50% 50% High efficacy full agonist Lower efficacy full agonist EC 50 Log [agonist] One 2 One Medicine: Pre-clinical revision course

9 Antagonist responses - Binds with a ffi nity and no e ffi cacy - Competitive = same binding site as agonist - Dissociates away - Can be overcome - Non-competitive = irreversible (covalent) - Removes receptor once bound - Increasing agonist has no e ff ect - Allosteric agonist / inhibitor = binds at di ff erent site One 2 One Medicine: Pre-clinical revision course

Antagonist responses 100% Competitive Non-competitive antagonist antagonist Response Log [agonist] One 2 One Medicine: Pre-clinical revision course

Key points G-proteins are activated by GTP, causing subunit - dissociation Increased ionisation of drugs reduces transmembrane - passage - Zero order elimination has a fixed amount removed per hour, with variable half-life - Competitive antagonists can be overcome by increasing agonist concentration One 2 One Medicine: Pre-clinical revision course