drug target

A drug target is the specific molecule in the body that a drug latches onto to do its job. If the drug is a key, the target is the lock. Hit the right lock and you open the door you intended; hit the wrong one and you may open a door you didn't want, which is where many side effects come from.

Most drug targets are proteins: receptors that receive chemical signals, enzymes that catalyze reactions, ion channels that gate the flow of charged particles across membranes, and transporters that ferry molecules in and out of cells. A few drugs act on nucleic acids or on structural components rather than on a single protein. The defining feature is that the drug binds the target with enough selectivity to change its function.

Identifying and validating the right target is the heart of modern drug discovery. A good target is one whose modulation reliably changes the disease and whose normal role can be altered without unacceptable harm. Even an excellent target is useless, however, if no molecule can reach it at a safe concentration, which is why target choice and pharmacokinetics must be considered together.