Partial agonists description

One-way analysis of variance, 229-230, 230f—231f Operational model derivation of, 54-55 description of, 45—47, 46f function for variable slope, 55 for inverse agonists, 221 of agonism, 47f orthosteric antagonism, 222 partial agonists with, 124, 220-221 Opium, 147 Orphan receptors, 180 Orthosteric antagonism... 

Both DCI and IEG are now classified as partial agonists. Partial agonist, by definition, is a comparative description. When substance B is unable to produce as large a maximum response as... 

FIGURE 11.7 Sensitivity of various descriptive parameters for concentration-response curves to drug-receptor parameters. (A) The location parameter (potency) of curves for full agonists depends on both affinity and efficacy. (B) For partial agonists, the location parameter (EC50, potency) is solely dependent upon affinity while the maximal response is solely dependent upon efficacy. 

Partial agonists, like full agonists, bind 100% of their receptors when present in high enough concentration. Therefore, the binding curve (but not the effect curve) will go to 100%. If the effect curve is curve 4 and many spare receptors are present, the binding curve must be displaced to the right of curve 4 (K > ECj ). Therefore, curve 3 fits the description better than curve 2. The answer is (C). 

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