Posted by Cam W. on April 15, 2000, at 14:35:33
In reply to Re: Heart pain, short breath after meds... ?, posted by Anna P. on April 15, 2000, at 13:56:32
> It's to advanced stuff for me, but what is cytozome P-450, and what can happen besides increasing the amount of the drug in the blood? Anybody?
>
> Anna P.Anna - The cytochrome system is a number of slightly different enzymes produced by the liver to convert hydrophobic, lipid soluble compounds (ones that dissolve in fats) into hydrophilic, water soluble ones. The kidney can excrete water soluble compounds in the urine easier than lipid soluble ones. The cytochrome system is the main detoxifying system of the liver.
Drugs are usually lipid soluble so that they have a longer half-life in the body. The drug can bind to plasma protein or hide in fat cells and slowly be released, rather than acting all at one time.
The cytochrome enzymes are divided into families and sub-families, depending on their structure and how they chemically act on a compound. Different sub-familes metabolize different compounds (not only drugs, but also foods, toxins, or nearly anything the body is trying to excrete).
The cytochrome enzymes use a number of chemical reactions to turn a compound water soluble: N-demethylation, carboxylation, oxidation, hydroxylation and N-methylation.
Some different ethic populations have livers that contain differing amounts of these enzymes, making them more (or less) susceptible to the effects of certain drugs. This is why different races are affected by drugs differnetly. Even within the same ethnic populations, variations occur, resulting in drugs having different effects and lengths of action in different people. This system is one of the reasons we say, that with drugs, "YMMV -your mileage may vary".
Some drugs can induce some families or sub-families of cytochrome enzymes. Drugs like Tegretol, Dilantin and barbiturates and cruciferous vegetables like brussel sprouts, cabbage and charbroiled meats and cigarette smoke can cause the liver to increase the amount of specific enzymes that the body produces. Other drugs that use this specific enzyme as a major metabolic route will be excreted from the body faster.
Conversely, other drugs, like Serzone, some SSRIs, Erythromycin and Tagamet and a food like grapefruit can inhibit certain cytochrome enzymes from being produced. Other drugs that use this system will have less enzyme present to metabolize them and may bulid up in the body to toxic levels.
Hope this wasn't too confusing - Cam W.
poster:Cam W.
thread:29757
URL: http://www.dr-bob.org/babble/20000411/msgs/30124.html