Partial Synthesis of Opioids with a Morphine Skeleton

9 Partial Synthesis of Opioids with a Morphine Skeleton 

Codeine is the monomethyl ether of morphine. It is metabolised to morphine, and possesses accordingly a morphine-like activity spectrum, although its potency is five to ten times weaker. It shows good oral bioavailability and is frequently used for the treatment of low to medium levels of pain, and also to suppress the urge to cough. Its potential for addiction at therapeutic doses is low. 

Even today, codeine is occasionally obtained by extraction from opium, although mostly by methylation of (-)-morphine. This methylation can be carried out selectively in a phase- transfer reaction with trimethylphenylammonium 

Codeine is by far the most widely used legal opiate in the world. The manufactured tonnage increased to 381 tonnes in 2011, the highest level ever reported. [82] 

Dihydrocodeine possesses a pharmacological profile related to that of codeine. It is generally administered orally. During chronic medication it may lead to dependence. The annual output fluctuates between 27 and 32 tonnes. [82] 

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