Valorphin: a novel chemical structure with opioid activity

Valorphin is a semisynthetic derivative of dihydrovaltrate with opioid analgesic activity. In vitro binding studies using brain homogenates from rat and guinea-pig indicate a preference for the mu-receptor site. Bath application to cultured cerebellar Purkinje cells inhibited the spontaneous firing, similar to the effect seen with morphine. Analgesic activity has been demonstrated in the hot plate and the tail flick test in the mouse and the Randall-Selitto test in the rat. In the rhesus monkey valorphin was self-administered, but naloxone challenge induced only mild withdrawal signs. Valorphin is a novel chemical entity, structurally not related to known opioids, which interacts preferentially with opiate mu-receptors.