Simple pA2 estimation of partial agonists: comparison with the Kaumann-Blinks method.

Estimation of KB and pA2 of partial agonists as antagonists of full agonists is hindered by their stimulant component of action. This reflects competitive synergism, i.e., an additive interaction with a full agonist. The antagonistic component of a partial agonist is seen as a parallel shift of the agonist curve to the right from a constructed additive dose-response curve, from which a dose ratio (DR) was determined for calculation of graphic estimation of KB or pA2 of partial agonists. Dose-response curves from eight studies were analyzed in this way, in comparison with the method of Kaumann and Blinks, and showed excellent agreement between pA2 values determined by either method (r = 0.994, slope = 0.999, n = 17).