The embodiments provide a modified calcitonin gene-related peptide antagonist including an N-terminal fragment of modified calcitonin gene-related peptide or related protein family member where at least two residues of the N-terminal fragment are cysteine (Cys) and at least one amino acid comprises a non-threonine substitution of a threonine (Thr) residue； a central core where the central core comprises an α-helix； and a C-terminal fragment of modified calcitonin gene-related peptide or related protein family member comprising a C-terminal amide and where at least one amino acid of the C-terminal fragment is phenylalanine (Phe), proline (Pro), tyrosine (Tyr) or hydroxyproline (Hyp) or pharmaceutically acceptable salt thereof, as well as compositions, including pharmaceutical compositions, comprising a subject peptide. The embodiments further provide treatment methods, including methods of treating a migraine, the methods generally involving administering to an individual in need thereof an effective amount of a subject peptide or composition.
