16 November 2007
How does codeine release histamine?
Simple answer: not known. There are 2 commonly used histamine releasers, codeine and compound 48/80, a synthetic polyamine. Codeine apparently is idiosyncratic: histamine release induced by codeine is not blocked by the opiate antagonist naloxone, and other opiates like fentanyl do not release histamine. Both codeine and 48/80 probably engage the downstream signaling pathway of the IgE receptor, mimicking crosslinking. This can be a side effect of codeine-related medications, as the other Dr. Cohen can attest, after being covered in hives when given some oxycodone.
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2 comments:
Interesting, yet curious--thanks.
Curious because codeine obviously has analgesic properties. It is metabolized in vivo into two active ingredients including morphine which binds the mu receptor. And naloxone has a high affinity for the mu receptors. I guess it makes sense then that codeine is engaging downstream IgE signaling.
In Goodman and Gilman's "The Pharmacological Basis of Therapeutics", the only immune effects of morphine-like drugs, besides the histamine-release of some but not all of them, is that they inhibit lymphocyte rosette formation as well as the cytotoxicity of natural killer cells. They also mention that this happens through a change in CNS signaling, but don't mention what that might be. I'll see if I can find anything else interesting...
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