EC50 and Spare Receptors

BSCC Pharmacology 003 Question: In relation to drug concentration and responses, what is the EC50 and what are spare receptors? Draw a dose response curve for an irreversible antagonist as the spare receptors become occupied. Examiner explanation: + Show: Drawing and explanation in real-time video/audio expand(document.getElementById('ddet1320909989'));expand(document.getElementById('ddetlink1320909989')) + Show Transcript expand(document.getElementById('ddet2102237374'));expand(document.getElementById('ddetlink2102237374')) In relation to drug concentration and responses, what is the EC50 and what are spare receptors? EC50 is the concentration at which an agonist produces half its maximal effect. I.e. the potency of the drug. The smaller the EC50, the greater the drug potency The concentration of an agonist producing a maximum response may not result in occupancy of all the receptors. These receptors are said to be “spare”. These spare receptors can either be in number i.e. there are an excess number of receptors, not all are occupied. Or temporal: the effect of activation of the receptor may be longer than the duration of drug-receptor interaction. I.e. may be longer than the time spent bound to the receptor. This results in “spare receptors” Draw a dose response curve for an irreversible antagonist as the spare receptors become occupied. The curves shift to the right as the spare receptors become occupied at increasing doses of antagonist. Curve A re...
Source: Life in the Fast Lane - Category: Emergency Medicine Authors: Tags: Basic Science Pharmacology BSCC EC50 Spare Receptors Source Type: blogs