Additional Thoughts on Acetaminophen & SSRIs [Updated!]

This is a follow-on to my blog: Acetaminophen SSRI interaction Responsible for Dangerous Behavior? which should be read first.

As an indication of the complexity of dosing and schedule along with interactions here are but two relevant studies of several published recently.

Study 1

These results suggest that down-regulation of 5-HT(2A) receptor in response to 5-HT release is a major step in the mechanism underlying analgesia produced by this agent [acetaminophen]. On the contrary, chronic use of acetaminophen may result in 5-HT depletion, which in turn produces re-adaptation of postsynaptic 5-HT(2A) receptors. These data provide further evidence for a central 5-HT-dependent antinociceptive [reducing sensitivity to painful stimuli] effect of acetaminophen.

http://www.nature.com/npp/journal/v38/n6/abs/npp2012258a.html?WT.ec_id=NPP-201305

So, Acetaminophen DOES affect the receptors involved in SSRIs treatment. Further, a reduction in sensitivity to painful stimuli also applies to psychological pain as seen in my previous blog.

Individuals in psychological pain may become chronic users of acetaminophen. It is well known that such individuals seek drugs to alleviate their discomfort and frequently turn to recreational and prescription drugs including prescription pain relievers. 

The possibility that pain relief seeking is an underling cause of some addiction should be investigated. And the chronic use of acetaminophen by those in psychological pain must also be researched!

Study 2

Altogether,  findings from this study provide insights into the serotonergic regulation of executive control processes and suggest that impaired 5-HT_2C receptor signaling during development may predispose to executive function disorders.

http://www.nature.com/npp/journal/v38/n6/abs/npp2012258a.html?WT.ec_id=NPP-201305

Additional Thoughts

Executive function disorders, among their other components, involve a lack of judgment and behavioral dis-inhibition. Such impairment could lead to violent behavior in some individuals.

Executive function disorders can, in my humble opinion, be exacerbated or simply become apparent during final brain maturation (just like adult onset schizophrenia). For those individuals who exhibit the disorder in childhood they may have taken or be taking Ritalin or related drugs. Such a history is likely to significantly effect any acetaminophen/SSRI interaction. And such a history is likely to contribute to violent behavior.

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