The invention describes compositions of peptide analogs exemplified by peptides derived from vasopressin, terlipressin, and GLP1 and others 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, wherein A is a hydrophobic moiety or a metal binding moiety, 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. A may be linked to Cm by a linker group. The peptide analogs are complexed with polymeric carrier to provide enhanced half-life.