This is what you said: > There are a few compounds (like fentanyl or LSD) where the dosages are so small and the compound so potent that 10-25% makes a differe

This is what you said: > There are a few compounds (like fentanyl or LSD) where the dosages are so small and the compound so potent that 10-25% makes a difference but for the majority, precision isn't that critical. As in, typical dosages for fent or LSD are on the order of micrograms, so we expect them to be sensitive to a 25% change, for other drugs where a typical dose is measured in mg or grams, 25% is less likely to be a big deal, etc. This is the only way to interpret what you wrote, and it doesn't make sense. No such trend exists. None of the "basic facts" which you "explained" above (which I already knew) go anywhere near supporting this assertion. Put another way, if you know the [A]50 you know one point on the dose-response curve, but in general that tells you nothing about the slope or shape of the curve near that point. Judging from your comment history, you are not an actual doctor or biomed researcher, just a programmer in that industry. Which makes your teeth-gnashing about what an authority you are a tad less persuasive.