Cyclized conotoxin peptides

A synthetically cyclised α- or ω-conotoxin peptide having an amide cyclised backbone such that the peptide has no free N- or C-terminus, said conotoxin peptide comprising either 4 cysteine residues which are bonded in pairs to form two disulfide bonds or 6 cysteine residues which are bonded in pairs to form three disulfide bonds, wherein said cyclised α-conotoxin peptide has α-conotoxin peptide activity and said cyclised co-conotoxin peptide has ω-conotoxin peptide activity.