does IV mean it doesn't metabolise by the liver

[phatass]

.......

 

[Diloadid]

it bypasses first pass metabolism in the liver... thats the best of my knowledge there. thx google.

 

[nAON]

^ first pass is only for drugs taken oral.

And even IV it's gonna get metabolised, any drug that goes into your body, irrespective of ROA, is gonna end up in the blood and then going through the liver. For certain ROAs though, like smoking, it goes to the brain before the liver.

 

[Tony Williams]

Drugs like diamorphine/heroin IV will cross the BBB and insted of the liver be metabolised by MOAI I believe. - correct me on this if I can wrong.

 

[Psychonauticunt]

a stupid question been on my mind for a while now... when you IV does that mean that the liver does not metabolise the molecule (yes i presume)
e.g. tramadol, the active metabolite that gets you high is O-desmethyltramadol.... is it metabbolised by the liver? then if you IV or plug eg. the tramadol ... do you get O-desmeth.....

hope this makes sense to someone and someone can answer.... does a metabolism have to pass by the liver?

Metabolism of xenobiotics (external compounds which cannot be used as food by cells) occurs mostly in the liver, but in trace amounts in various places over the body. The enzymes which break down drugs into inactive compounds are found at much higher concentrations in the liver than anywhere else, so most of the metabolism of drugs occurs there.

Routes of administration other than oral avoid first-pass metabolism; this means they reach the brain and systemic circulation before the liver. Going through the liver first means that a given % (depends on the drug and person) is broken down before reaching the brain, and therefore exerting any effects. With most (in fact I think almost all) drugs, IV injection yields 100% bioavailability.

The liver still metabolizes the drug; the enzymes there break down drugs in the blood that passes through it.

Taking tramadol by other methods, including I.V. or I.M. injection, still yields O-Desmethyltramadol as a metabolite. For this not to happen, something else in the body would have to break down the tramadol before it reaches the liver.

Drugs like diamorphine/heroin IV will cross the BBB and insted of the liver be metabolised by MOAI I believe. - correct me on this if I can wrong.

For a drug to have effects on the brain, it must be able to cross the BBB - certain drugs like diamorphine and methamphetamine just do this particularly quickly. Diamorphine is converted into 6-monoacetylmorphine and then morphine by process of deacetylation in the brain. After this, the morphine is metabolized by the liver (and some is excreted unchanged).