potency–property balance

Potency–property balance is the recognition that binding harder is not free. Every trick that makes a molecule grip its target more tightly tends to charge a toll somewhere else, in solubility, metabolism, size, or safety. It is like loading a backpack with useful gear: each item helps, but at some point the pack becomes too heavy to carry.

Many of the easy ways to gain potency, such as adding hydrophobic bulk to fill a pocket, also raise lipophilicity, which worsens solubility, increases metabolic clearance, and invites off-target binding. So a molecule that looks better on the potency readout can be a worse drug overall. Chemists therefore judge analogs not by raw potency but by whether they gain affinity efficiently, watching metrics like ligand efficiency and lipophilic ligand efficiency.

The goal is rarely maximum potency; it is sufficient potency carried by a healthy property profile. Often the smarter move is to stop pushing affinity once it is good enough and spend the remaining effort fixing solubility or clearance, because a slightly less potent molecule with clean properties usually makes a far better medicine.