The invention describes compositions of peptide analogs that are active in blood or cleavable in blood to release an active peptide. The peptide analogs have a general formula: A-(Cm)x-Peptide (SEQ ID NO: 76), wherein A is hydrophobic moiety or a metal binding moiety, e.g., a chemical group or moiety containing 1) an alkyl group having 6 to 36 carbon units, 2) a nitrilotriacetic acid group, 3) an imidiodacetic acid group, or 4) a moiety of formula (ZyHisw)p (SEQ ID NO: 50), wherein Z is any amino acid residue other than histidine, His is histidine, y is an integer from 0-6； w is an integer from 1-6； and p is an integer from 1-6； wherein if A has alkyl group with 6 to 36 carbon units x is greater than 0； and Cm is a cleavable moiety consisting of glycine or alanine or lysine or arginine or N-Arginine or N-lysine, wherein x is an integer between 0-6 and N may be any amino acid or none. The peptide analogs are complexed with polymeric carrier to provide enhanced half-life.
