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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 4 of 4. This is the beginning of the thread.
Posted by BabyBunny on June 8, 2007, at 7:47:03
Hi all. It's me once again. LOL
I am just wondering if someone would please be so kind as to explain to me in layman's (sp?) terms what the words in the subject title actually mean in regard to psychitry. Also what about CYP-2D6 and CYP-3A4?
My new medication, Invega (Palperidone) says the following and I'd just like to know a bit more about what I'm reading and taking:
Properties:
*Benzisoxazole
DA2 antagonist
5-HT2A antagonist
NE alpha-1 antagonist
NE alpha-2 antagonist
H1 antagonistHalf-Life & Metabolism:
23 Hours
CYP-2D6
CYP-3A4I believe that DA2 is a kind of Dopamine, 5-HT2A is some type of Serotonin, NE Alpha 1 & 2 are some kinds of Norepinephrine and H1 is a type of Histamine.
But in all honesty I really don't know much about this stuff. Can ya tell? LOL So if anyone would be so kind as to please enlighten me I'd be most thankful. I really would like to know more about what I'm putting into my body and what it's doing in there.
Thanks again. :)
Hugs,
BB
Posted by Racer on June 8, 2007, at 11:20:49
In reply to What Do These Mean: Inhibitor, Antagonist, Agonist, posted by BabyBunny on June 8, 2007, at 7:47:03
> Also what about CYP-2D6 and CYP-3A4?
These are enzymes that break down drugs. I believe they're produced in the liver, but my brain is so fried this morning I can't promise I know my own name, let alone liver enzymes...
Anyway, these enzymes affect the way substances behave in your body. Since these are kinda like the janitors of the system, their actions will have a lot of impact on whether a drug sticks around to build up a high enough level to work, versus getting cleaned up before it could do anything much at all.
>
> My new medication, Invega (Palperidone) says the following and I'd just like to know a bit more about what I'm reading and taking:
>
> Properties:
> *Benzisoxazole
> DA2 antagonist
> 5-HT2A antagonist
> NE alpha-1 antagonist
> NE alpha-2 antagonist
> H1 antagonist
>
> Half-Life & Metabolism:
> 23 Hours
> CYP-2D6
> CYP-3A4
>
> I believe that DA2 is a kind of Dopamine, 5-HT2A is some type of Serotonin, NE Alpha 1 & 2 are some kinds of Norepinephrine and H1 is a type of Histamine.
>OK, much of that is mostly right. DA2 actually refers to a type of dopamine *receptor,* since there's really only one kind of dopamine. Same with the others, but the basic idea is right. DA is dopamine, NE is norepinephrine, and 5HT is serotonin (or 5-hydroxytriptamine, which I've probably misspelled...)
Antagonist -- actually, this is just what it sounds like. It "antagonizes" a receptor, so that it isn't available. It's easiest for me to think about it using a ligand gated ion channel as an example -- and don't think too much about this: think of the receptor as being like a drawstring bag; the antagonist would be pulling the bag closed, so nothing can get in. The Agonist, on the other hand, would be forcing that bag to stay open, so that more stuff can get in. Does that make sense?
What that means in psychiatric terms is that an antagonist is going to reduce the activity of a certain chemical messenger on a certain receptor, and an agonist is going to increase it.
Inhibitor, of course, means just that: something which inhibits. In the case of a Selective Serotonin Reuptake Inhibitor, for example, the drug inhibits the action of the chemical that mops up serotonin after it's been used to deliver a message. That leaves the serotonin hanging around, pretty much trying to deliver that message again. It's nto inhibiting the serotonin, it's inhibiting the serotonin reuptake molecule.
I'm not sure any of that makes sense. I am having vision problems again, and it's hard for me to tell if I make sense when I can't see to read what I've written... I hope it does, and I hope it helps.
Posted by Phillipa on June 8, 2007, at 12:46:22
In reply to Re: What Do These Mean: Inhibitor, Antagonist, Ago, posted by Racer on June 8, 2007, at 11:20:49
Racer nothing against you but I am so dense I still don't get it love Phillipa
Posted by Larry Hoover on June 12, 2007, at 11:22:21
In reply to What Do These Mean: Inhibitor, Antagonist, Agonist, posted by BabyBunny on June 8, 2007, at 7:47:03
> Hi all. It's me once again. LOL
>
> I am just wondering if someone would please be so kind as to explain to me in layman's (sp?) terms what the words in the subject title actually mean in regard to psychitry.An inhibitor is a substance that reduces the rate of a biological process, i.e. dx/dt is decreased. Two common instances are the serotonin reuptake inhibitors, and the monoamine oxidase inhibitors.
Serotonin reuptake inhibition occurs by temporary binding of e.g. Prozac molecules to the reuptake pump (transporter) active site. As long as Prozac occupies that special region, serotonin can't fit in, and it is forced to remain in the synapse. The SSRI antidepressants are not believed to damage the reuptake pumps, but only to delay their normal function.
In contrast, some MAOIs such as Nardil and Parnate do more than temporarily bind to the enzyme responsible for the degradation of neurotransmitter molecules. They destroy the enzyme's activity entirely, an irreversible process. There are also MAOIs that act more like the SSRIs, by only temporarily occupying the enzyme active site, e.g. moclobemide (Aurorix/Mannerix). The latter is a reversible inhibitor of monoamine oxidase.
Just for thoroughness, there are substances that increase the rate of biological processes, and those are known as inducers. There are numerous mechanisms of inhibition and induction. I've just given simple examples.
Antagonism and agonism refer to activity at receptors. The examples I used for inhibitory actions involved special proteins that changed the concentration of a substance, either by moving it from one side of a membrane to another (the reuptake pump example), or by converting to another molecule altogether (the enzyme example). Receptors only react to the concentration of a molecule, rather than change it. All these proteins (transporters, enzymes, receptors) have active sites, very special pockets into which specific molecules tightly bind. There are pumps that are designed just for serotonin, and enzymes which specialize in creating it or destroying it, but it's the receptors that actually respond to it. It's the nature of the response of the receptor to foreign molecules that is described by the terms agonism or antagonism.
A receptor agonist activates the receptor even in the absence of its natural ligand (the stuff that normally binds there). Amphetamine activates dopamine receptors, even when neurons are not actively releasing dopamine. Therefore, there is a dopamine-like effect, caused by ampthetamine's agonism of the dopamine receptor.
An antagonist is any substance that blocks the activation of a receptor by any agonist (either the natural ligand, or an artificial one).
A reverse agonist is a substance that causes a receptor to do the opposite of what it normally does.
As you can imagine, there is a large range of receptor responses that can occur after something binds to it. Negative response, no response, positive response.....but also partial response (e.g. partial agonism), or excessive response (i.e. greater than that from the natural ligand).
We now are beginning to recognize that the very same chemical, acting at one type of receptor, can act as an antagonist at one concentration, but as an agonist at another. Is it any wonder this gets confusing?
There are many different mechanisms of agonism and antagonism, so I won't even begin to give examples.
> Also what about CYP-2D6 and CYP-3A4?
Those are specific examples of enzymes found in the liver and the walls of the intestine. They are designed to detoxify (primarily) things we've swallowed, but which might injure us.
They are called either the cytochrome enzymes, or the P450 enzymes (or both). They are categorized hierarchically, by alternating numbers and letters.
Many drugs depend on 3A4 and 2D6 for elimination from the body. Drug interactions often involve disturbances in the function of these enzymes caused by competition for access to these detoxificating enzymes.
> My new medication, Invega (Palperidone) says the following and I'd just like to know a bit more about what I'm reading and taking:
>
> Properties:
> *Benzisoxazole
> DA2 antagonist
> 5-HT2A antagonist
> NE alpha-1 antagonist
> NE alpha-2 antagonist
> H1 antagonist
>
> Half-Life & Metabolism:
> 23 Hours
> CYP-2D6
> CYP-3A4
>
> I believe that DA2 is a kind of Dopamine....receptor. Dopamine receptor family A, type 2.
> 5-HT2A is some type of Serotonin
....again, receptor. There are at least 7 different families of serotonin receptors, and many different subtypes of some of those receptors, making for around a couple of dozen different serotonin receptors.
, NE Alpha 1 &
2 are some kinds of Norepinephrine and H1 is a type of Histamine.... again, both receptor types.
> But in all honesty I really don't know much about this stuff. Can ya tell? LOL So if anyone would be so kind as to please enlighten me I'd be most thankful. I really would like to know more about what I'm putting into my body and what it's doing in there.
>
> Thanks again. :)
>
> Hugs,
> BBWell, if I've raised more questions than I've settled, please feel free to ask more questions.
Yer welcome,
Lar
This is the end of the thread.
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