Maximal agonist effect

Here, EAmvm is the maximal possible effect of the agonist at maximal antagonist concentrations, and is thus 0 when fi = — 1. is the maximal agonist effect at the studied antagonist concentration [B ] ... 

Figure 1 Time course for effects of the mixed opioid agonist DPI-3290 on anti-nocieption and blood pC02 levels in alfentanil-infused rats. Alfentanil was intravenously infused at 6 pg/kg/min. At the time points outlined in the figure, radiant tail flick testing and arterial blood samples were collected and analyzed by standard methods. Antinociception was expressed as maximal percent effect (MPE).

The molar concentration of an agonist that produces 50% of the maximal possible effect of that agonist. 

The equation describing agonist-receptor occupancy under conditions of noncompetitive antagonism is given by Equation 6.8. The effect of antagonist on the maximal agonist-receptor occupancy (i.e., as [A] > oo) and compar-... 

FIGURE 11.20 Inhibition curves in PIC50 mode that do not show complete inhibition. (A) A partial agonist will depress the agonist response only to the point equal to the maximal direct agonist effect of the partial agonist. (B) An allosteric modulator that produces a submaximal decrease in affinity or efficacy of the agonist can also produce an inhibition curve that does not extend to basal (zero response) levels. 

The partial agonist concept was additionally refined by Stephenson (33), who introduced the concept of efficacy, e, which differed from intrinsic activity in that the latter was defined as a proportion of the maximal response [effect = a (RL)]. This concept was extended to situations where a maximal response to an agonist could occur when only a small proportion of the total number of receptors on a tissue were occupied, as in the situa-... 

When opioids are deemed necessary to estabhsh or maintain effective pain control, caregivers often face a controversial dilemma regarding whether weak or potent agonists should be employed Conventional stepwise care plans recommend that caregivers prescribe weaker agents including tramadol, buprenorphine, hydrocodone, and oxycodone, while maximizing their effectiveness with non-opioid... 

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