Hi. I've never learnt pharmacology but since I'm interested in it, I can't leave this topic unclear. Reading about cannabinoid receptor ligands, I messed up in binding affinities. As I know from internet, binding affinity is how strongly a particular substance binds to a receptor. Substances with higher affinity has stronger effects on receptor than lower ones, right? And the unit for binding affinity is nM which is a measure of concentration. For example substance with binding affinity of 1 nM has stronger effects than 0.1 nM right? Sometimes another molar unit micromole is used (i can't type that symbol of micro). Micromolar is much bigger than nanomolar so it should have higher affinity for receptors. But on the contrary, cannabonoid receptor substances that have binding affinity measured in nM are stronger than those measured in micromolar (for example 5 nM is stronger than 50 micromolar). Why it is so? Thanks