DPDPE ([{{Small|D}}-{{abbr|Pen|penicillamine}}<sup>2</sup>,{{Small|D}}-{{abbr|Pen|Penicillamine}}<sup>5</sup>]enkephalin) is a synthetic opioid peptide and a selective agonist of the δ-opioid receptor (DOR) which is used in scientific research.[1] It was developed in the early 1980s and was the first highly selective agonist of the DOR to be developed. It was derived from structural modification of met-enkephalin.[2]