site-specific delivery

Site-specific delivery aims to release a drug selectively at one chosen place in the body, rather than letting it act everywhere it travels. Think of watering a single plant with a long-spouted can instead of soaking the whole garden.

There are two broad ways to reach a chosen site. One is to put the dose physically at the site, as with an eye drop on the eye, an inhaler into the lungs, or a tablet engineered to break open only in the colon. The other is to send the dose through the bloodstream but design it to release or act only at the target, using the targeting carriers, ligands, or stimuli-responsive triggers described elsewhere in this field. The first approach is usually far more reliable than the second.

Delivering to a site concentrates the drug where it is needed and limits exposure elsewhere, which can mean smaller doses and fewer side effects. But true site-specificity is hard to achieve through the bloodstream, because the body distributes and clears drugs broadly, and even local administration can let drug escape into the general circulation. Many products described as targeted achieve only a partial, relative enrichment at the site rather than exclusive delivery.