Opioids Morphine Oral Bioavailability...

[EEhouseEE]

If you take 150mg morphine orally and this drug has a 30% bio-availablility this route then this means your only taking about 50mg right ?
Is that other 100mg gone completely to waste or what exactly happens, therapeutic and recreational wise, is the 50mg amount all that is hitting you in both cases and the other 100mg completely gone to waste ?. If so this means everytime somone takes morphoine orally they need to multiply their real dose by 3 if you get what i mean..what a confusing thing.lol

 

[sekio]

If you take 150mg morphine orally, only about ~30 percent of it makes it into your blood (50 mg). The rest either stays in your digestive tract and leaves your body naturally, or is broken down in your liver as soon as it is absorbed. (so yes the other 100mg does go to waste)

When people say they take 150mg morphine orally, that doesn't mean they *actually* take 450, it means they take 150 knowing that only 30% is absorbed.

Plugging pH-adjusted morphine can be up to 80% bioavailibility, try it.

 

[Tommyboy]

If you take 150mg morphine orally and this drug has a 30% bio-availablility this route then this means your only taking about 50mg right ?
Is that other 100mg gone completely to waste or what exactly happens, therapeutic and recreational wise, is the 50mg amount all that is hitting you in both cases and the other 100mg completely gone to waste ?. If so this means everytime somone takes morphoine orally they need to multiply their real dose by 3 if you get what i mean..what a confusing thing.lol

Why would they need to multiply their dose by 3? The only reason why you would do that is if you normally IV the drug getting 100% of it, and are then taking it orally and want to get the equivalent dose as you would if taking it orally.

What happens to the rest of the drug? When taken orally drugs go through first-pass metabolism which is when it goes through the liver before reaching the rest of the body. The liver absorbs some of the drug, and in the case of morphine it absorbs about 90% of the drug before leaving the liver and going through the circulatory system where it reaches the rest of the body.

So if someone usually IV's 30mg of morphine, then they would have to take around 90mg orally to get about the same effects. It doesn't matter if you are taking it therapeutically or recreationally, the bioavailability is still the same and the same amount is lost in first-pass metabolism.

This is a basic concept that has been covered extensively both on bluelight and in other places that can easily be found by doing a search. Since there isn't much that can be added to this I am going to close this thread.