Dynorphin
endogenous
What it isEndogenous kappa opioid peptide.
Why this oneKappa activation causes dysphoria rather than euphoria, which is why kappa agonist drugs are limited and kappa ANTAGONISTS are studied in depression.
What limits itIt explains the dysphoric quality of pentazocine, butorphanol and nalbuphine.
NO BOXED WARNINGS
Principal riskEndogenous or dietary; no boxed warning applies