What is the mechanism of action of Levopront (generic name), in a patient with an unspecified medical condition and no provided demographic or medical history?

Mechanism of Action of Levopront (Levorphanol)

Primary Mechanism

Levorphanol is a full mu-opioid receptor agonist that produces analgesia through direct activation of CNS opioid receptors, with additional activity at delta- and kappa-opioid receptors at higher doses, and functions as an N-methyl-D-aspartate (NMDA) receptor antagonist. 1

Detailed Pharmacological Actions

Opioid Receptor Activity

• Levorphanol is relatively selective for the mu-opioid receptor, which mediates its primary analgesic effects 1
• At higher doses, it binds to delta- and kappa-opioid receptors, providing broader pain modulation 2
• As a full opioid agonist, there is no ceiling effect for analgesia—dosage can be titrated upward as needed, limited only by adverse effects including respiratory and CNS depression 1

NMDA Receptor Antagonism

• Like methadone, levorphanol acts as an antagonist at N-methyl-D-aspartate receptors, which may provide additional benefit for neuropathic pain 2
• This dual mechanism (opioid agonism + NMDA antagonism) distinguishes levorphanol from simpler opioid analgesics 2

Central Nervous System Effects

• Levorphanol produces analgesia through direct action on specific CNS opioid receptors identified throughout the brain and spinal cord 1
• It causes respiratory depression by reducing the responsiveness of brain stem respiratory centers to both carbon dioxide retention and electrical stimulation 1
• The drug produces miosis (pinpoint pupils) even in total darkness through direct CNS action 1

Pharmacokinetic Advantages

• Levorphanol has a shorter half-life and more predictable metabolism compared to methadone 2
• The morphine-to-levorphanol conversion ratio varies based on baseline morphine dose: 12:1 for <100 mg morphine, 15:1 for 100-299 mg, 20:1 for 300-599 mg, and 25:1 for >600 mg morphine 2

Additional Physiological Effects

Gastrointestinal System

• Levorphanol reduces motility and increases smooth muscle tone in the stomach and duodenum 1
• It decreases propulsive peristaltic waves in the colon while increasing tone to the point of spasm, resulting in constipation 1
• May reduce biliary and pancreatic secretions and cause sphincter of Oddi spasm 1

Cardiovascular System

• Produces peripheral vasodilation that may result in orthostatic hypotension or syncope 1
• Manifestations of histamine release include pruritus, flushing, red eyes, sweating, and orthostatic hypotension 1

Endocrine System

• Inhibits secretion of ACTH, cortisol, and luteinizing hormone 1
• Stimulates prolactin and growth hormone secretion 1
• Extended use may lead to hypogonadism with symptoms including low libido, impotence, erectile dysfunction, amenorrhea, or infertility 1