Levorphanol

Mechanism of action:
Levorphanol is an opioid and belongs to the morphinan derivatives. Levorphanol activates the μ-opioid receptor, which inhibits neuronal adenylate cyclase and reduces cAMP production. It also inhibits presynaptic voltage-gated Ca2+ channels, preventing calcium influx and reducing the release of pain-related neurotransmitters such as glutamate and substance P. At the same time, it activates postsynaptic K+ channels, promoting potassium efflux and leading to neuronal hyperpolarization.
Reference(s):
1. Allen RM et al. (2003). The competitive N-methyl-D-aspartate receptor antagonist (-)-6-phosphonomethyl-deca-hydroisoquinoline-3-carboxylic acid (LY235959) potentiates the antinociceptive effects of opioids that vary in efficacy at the mu-opioid receptor. J Pharmacol Exp Ther.
2. Prommer E et al. (2007). Levorphanol: the forgotten opioid. Support Care Cancer.
