Re: Pharmacology of Narcotics

[Guest guest]

Dear and All

Nice work!

Here are my additions and " changes " :

The opioid receptor is called the Mu, not the Mm receptor. Mu is

pronounced MEW like the sound that a kitten makes. Mu also is denoted

by the GREEK symbol that looks like a " U " with a 'tail' in the " front "

of it.

In addition, the receptors are not ONLY pain receptors. These SAME

receptors can receive the endorphins (that you spoke of) AND

enkephalins, creating the feeling of pleasure and joy. These are the

body's own pleasure or feel good chemicals which are technically

endogenous opioid peptides or proteins. This is why people can become

addicted to certain activities such as sex or gambling etc..

There are 4 not 3 opioid receptors. They are Mu, Kappa, Delta and

Sigma. The three that are associated with endorphins and pain are Mu,

Kappa and Delta, with the least research information on the Delta

receptors. The sigma receptors are mainly associated with the unwanted

psychotomimetic effects, (mimic psychosis) of dysphoria, confusion and

hallucinations. Kappa receptors also display some psychotomimetic

effects. Narcotics can bind to any of the 4 receptors, but mainly to

the Mu and Kappa receptors. Narcotic Analgesics mainly bind to the Mu

receptors.

Mu receptor stimulation causes respiration depression (lowered

breathing ability and cough supression), analgesia, miosis

(constriction of the pupil) and decreased motility which leads to

constipation, and the feeling of a happy-well-being state called

'euphoria'. It has been postulated that it is this euphoria that

causes one to become addicted to a narcotic.

K or Kappa receptors are mainly located on the spinal cord causing

analgesia, psychomimetic effects and dysphoria, respiration

depression, miosis and constipation, . Dysphoria is the opposite of

the happy well being state, or sometimes referred to as a 'negative'

high or bad trip. Greater respiratory depression and greater miosis

occurs with K receptor stimulation (activation) than with the Mu

receptors.

Delta receptors are sometimes referred to in text with a symbol that

looks like a Greek letter D or a 'vertical' infinity sign or a

vertical alpha sign. Little is known about the result of Delta

receptor activation in humans. But animal models have shown analgesia

and increased effects on supraspinal sites and block or pain

reception. Pain reception is called nociception, therefore narcotics

have an anti-nociception property.

It is very important to note also that if one is administered Narcan /

naloxone, a narcotic antagtonist, as an antedote, within the right

time frame, the Narcan will 'knock out " the narcotic/opioid or

opioid-like substance from the opioid receptor sites. This will

reverse the respiratory depression, miosis, sedation and low blood

pressure or hypotension. The most accepted mechanism of action that

of competitive inhibition, whereby the Narcan `fights' the morphine to

get into the opioid receptor site first. Narcan does nothing except to

take up the space in the receptor blocking the action of morphine or

opioid. Narcan has no pharmalogical activity. The Time of effect of

naltrexone is dose-dependant, doubling the dose or tripling the dose

will double the 24 hr effect or triple it.

Please ignore my previously reply post as it was not completed and edited.

It should also be noted that CII substances include, stimulants

depressants and analgesics. However, if the CII is not an opium or

opioid (opium-like substnace) it is NOT a narcotic.

Most Respectfully,

Jeanetta Mastron CPhT BS

Pharm Tech Educator

Founder/Owner

>

> Opioid Analgesics (Narcotics) are drugs that act on the Central

> Nervous System (CNS). Narcotics should not be confused with

> anesthetics; which actually block sodium ions from reaching the brain,

> telling it about pain. Narcotics merely slow the reactions of the CNS

> to pain. This along with a feeling of euphoria, allow the individual

> to deal with the pain. Within the CNS there are substances called

> Endogenous Peptides. These peptides include Endorphins (The word

> endorphin coming from a combination of endogenous and morphine) these

> endorphins are four times more potent than morphine itself. Endorphins

> are believed to play a crucial role in survival. Once released, they

> provide enough pain relief for a person in danger to get out of harms

> way. Now within the CNS there are Receptors for these endorphins

> (Think of receptors like those children's toys with the different

> shaped blocks that fit into holes of the same corresponding shape.

> There are many different kind of receptors in the body for a variety

> of substances, each with it's own unique shape, and only substances of

> the same type as the receptor will fit.) This is relevant because

> morphine along with other narcotics, bind to these opioid receptors

> and mimic the actions taken by endorphins and other endogenous

> peptides. Now there are three different types of opioid receptors in

> the CNS, each believed to deal with a different kind of pain. Mm

> receptors, Kappa receptors and Delta receptors, with Mm receptors

> being the one morphine and most narcotics bind to.

> So from the beginning; morphine along with most narcotics is basic,

> meaning it would be best absorbed in the intestines, which is

> primarily composed of alkaline fluid. Once absorbed morphine is

> carried to the brain via blood, where it binds to the Mm receptor

> mimicking the actions of endorphins and other endogenous peptides.

> While in circulation, morphine is metabolized in the liver into two

> Metabolites M3G and M6G, and these morphine metabolites along with a

> small percentage of unmetabolized morphine are excreted mainly in

> urine. As a side note, there is a contradiction between morphine and

> some diuretics. Because some diuretics cause urine to become slightly

> alkaline, there becomes the possibility of reabsorption. This in turn

> can raise the plasma concentration and run the risk of drug toxicity.