BARRIERS TO DELIVERY OF MACROMOLECULES

Drug efficacy depends on timely delivery to the site of action. Recogn ition of this fact is particularly important in the design of macromol ecular drugs, whose size may slow delivery. This review describes four major biological barriers to the delivery of macromolecules: 1) epith elial and endothelial cell layers, 2) the basement membrane, 3) tissue s and 4) in vivo degradation or inactivation. Current research related to each barrier is presented, and the implications for macromolecular drug design are discussed.