Addressing peptides http://www.bing.com/...essing peptide" are peptides published as causing things to go to particular places at the body. some listed online carry material through mitochondria as well as other membranes. I think that linking these addressing peptides to little pharmaceutical molecules brings active drugs to particular places at the body providing benefit. while that is pretty obvious consider that if a person takes a lipid soluble drug, it likely concentrates all over the body where there are lipids. Thus a system that brings lipid soluble drugs to aquaeous cytoplasmic environments could bring stronger effect or new effect or more precise effect from a known beneficial drug. From a longevity perspective what might deprenyl or metformin or spermidine do if attached to an addressing peptide that brought them to the cytoplasm
thus I think existing as well as new longevity drugs should be tested with adressing peptides to find better or new effects.
rather weirdly I have not found a reference online where a person attaches an addressing peptide to a less than 400 AMU pharmaceutical molecule. so basically, any little molecule with an addressing peptide is a new drug.