Posted by chemist on May 9, 2005, at 3:50:50
In reply to Will ketamine trigger or cause schizophrenia?, posted by AMD on May 8, 2005, at 22:17:30
> Subject says it all. I took a bit this week and I'm worried now that I am going to worsen my bipolar and trigger it into flashbacks and schizophrenia's negative and positive symptoms. Is this realistic? Just what I need.
amd: ketamine is an anesthetic that is noteworthy if only because it is used when one need worry about a patient's heart rate dropping into the danger zone. the positive and negative affect of schizophrenia involve specific dopamine receptor subtypes in very specific areas of one's brain. ketamine does as anesthetics do and is most active in the limbic system, followed by inhibition of neurotransmission in the cortex. i am certain that ketamine keeps the blood pressure from dropping by increasing the quantity of noradrenaline and adrenaline in the synaptic cleft, and NMDA receptors are hit: i am equally certain that the D_{2}/D_{3} receptors and dopaminergic neurons in the substantia nigra are not being targeted, and any hallucination and/or dissociation are/is not uncommon when a patient emerges from being put under. keep in mind that these statements refer to patients who have been anesthesized with the drug before a surgical procedure, and do not mistake the emergence psychoses with the onset of schizophrenia. while the catecholamine hypothesis could be invoked here - especially in light of the NA/A action - it is likely a relavent theory applied to a tangential problem. interesting - to me, at least - is the recommended administration of atropine or scopolamine, which will reduce excessive salivation: i am not aware of a relation between AChE binding - neuromuscular junction or neuronal - and this drug, and atropine and scopolamine are not to be used unless exposure to (this is one case at least) an AChEI/BuChEI such as a nerve agent has been confirmed. in any event, it does not make pre\"existing conditions any better nor does it preclude the more rapid emergence of as-yet-unseen problems from presenting (both noted by medhead)...the most effective antipsychotics for treating positive affect schizophrenia are those with very high affinity for the D_{2} or, more usually, D_{3} receptor subtype.
if you request a very real worry concerning a dopamine-related malady and drugs found on the street/in the gutter, i refer you to a manuscript that you ought to peruse (it is a 2-page journal article and the point is clear): namely a study that was published in Science in 1983 (Langston et al., 979-980). in san francisco in the early 1980s, MPTP showed up in ``heroin'' which in turn showed up in the bodies of six visitors to the ER in a short period of time. unfortunately for the users, they are the cohort that confirms that MPTP can induce irreversible Parkinson's disease. i do know that this is not a singular report and that caveat emptor applies in every market. all the best, c
poster:chemist
thread:495381
URL: http://www.dr-bob.org/babble/subs/20050506/msgs/495439.html