Protease inhibitors, which are metabolized
in the liver by the cytochrome P450 system, will cause increased concentrations of many drugs that are metabolized
by the same pathway The long list includes calcium channel blockers, statins, sulfonylureas, and selective serotonin-reuptake inhibitors.
For example, if the route is ingestion, much of the chlorpyrifos may be metabolized
to TCPy in the first pass effect before chlorpyrifos reaches the maternal systemic blood supply and hence the placenta (Figure 2).
In some cases, drugs become active only after they are metabolized
CYP2D6 codes for enzymes that metabolize chemicals such as medications that target the central nervous system (including various antidepressants, stimulants, and codeine--all drugs with different chemical structures), drugs of abuse, neurotoxicants, procarcinogens (substances that become carcinogenic only when metabolized
into more reactive compounds), and even the body's own neurotransmitters.
Scientists have long known that the human body initially metabolizes about 90 percent of its nicotine load into cotinine, which is then further metabolized
into a variety of other compounds.
Further, as indicated above, DEHP is rapidly metabolized
to its corresponding monoester, MEHP [mono-(2-ethylhexyl) phthalate].
Many drugs are metabolized
in the intestines before they can enter the blood.
Morton says the models could be used to study the fate of a molecule, from administration of or exposure to a toxic compound, to distribution to tissues through metabolism, to excretion--"imagine a toxic agent as a signal that enters the body and gets processed or metabolized
, and the outcome is disease in the human body," he explains.
To do so, he and Muller speculate, the organism stole many of the genes normally used by the bacterium, such as those encoding proteins that take in organic molecules and convert them to pyruvate, a carbohydrate that is directly metabolized
by the bacterium.