Levomethorphan

Levomethorphan

Levometorfan structure

Levomethorphan is recognized as the l-stereoisomer of methorphan. For those uninitiated with stereochemistry, isomers are molecules with the same molecular formula but different structural arrangements. The 'l-' prefix denotes a particular spatial orientation of the molecule, which significantly influences its physiological effects.

Isomeric Differences: Levomethorphan vs. Dextromethorphan

While methorphan exists in two isomers, their effects are vastly divergent:

• Dextromethorphan functions as an antitussive (suppresses cough) at lower doses, and at much elevated doses, it behaves as a dissociative substance.
• Levomethorphan, on the other hand, is an opioid analgesic, rendering it effective for pain relief.

Pharmacological Aspects

Levomethorphan exhibits effects akin to another compound, levorphanol. However, there's a catch! Levomethorphan is less potent initially because it requires transformation by liver enzymes to unleash its active form. Essentially, the body converts Levomethorphan to a more effective analgesic upon ingestion. This transformative process can draw parallels with how codeine is related to levorphanol, thereby making levomethorphan the codeine analogue of levorphanol.

Regulations and Legal Status

Legal frameworks around the world treat levomethorphan with caution, given its opioid nature:

• It's enshrined in the Single Convention On Narcotic Drugs 1961, placing it in the same regulatory basket as morphine for most nations.
• In the United States context, it's classified as a Schedule II Narcotic controlled substance. It has a DEA ACSCN (Drug Enforcement Administration Controlled Substance Code Number) of 9210. In 2013, the annual aggregate manufacturing quota for this substance stood at 6 grammes.
• Although there are different salts derived from levomethorphan, including the tartrate and hydrobromide, no pharmaceuticals containing levomethorphan are currently marketed in the U.S.

Comparison with Other Compounds

See Also

• Codeine - A prodrug in the opioid category that undergoes a transformation in the body to produce its effects.
• Dextromethorphan - The other isomer of methorphan with antitussive properties.
• Racemethorphan - A compound related to the methorphan family.
• Morphinan - The parent structure from which compounds like methorphan are derived.

Conclusion

Understanding levomethorphan not only enriches our knowledge about the world of opioids but also emphasizes the importance of stereochemistry in the realm of pharmacology. While two compounds may seem identical on paper, a subtle twist in their structure can translate to profoundly different effects in the human body.