enzyme induction?

[rachel200202]

i am currently working towards my nvq level three, i just cant get my head around the enzyme induction process, can any body help??

[Asterix]

hi rachel, i can definetly help, what context are you talking about, a drug interaction?

induction basically means an increase in. So say you have a drug which induces liver enzymes, the metabolism of a drug will be higher as liver breaks down drugs so more enzymes quicker the breakdown. if you tell me what it is exactly, i will be try my best to explain.

[rachel200202]

hiya, the exact question is in relation to drug metabolism describe the process of enzyme induction.

[Asterix]

ok cool, so have you looked at any examples as of yet lovely. google 'rifampicin' as an enzyme inducer.

also its related to the liver as its metabolism so the enzymes that are induced are known as cytochrome p450 enzymes

[Nik]

A drug which induces liver enzymes will induce the synthesis of new enzymes capable of breaking down drugs which it metabolises. In some cases (e.g. carbamazepine) drugs can induce the synthesis of enzymes (known as CYP3A4 in the carbamazepine case) which then break down that drug, i.e it induces its own metabolism.

[El-loco]

It is significant because, for example, rifampicin and phenytoin, both of which increase the production of enzymes that break down certain drugs will increase the speed of breakdown of, for instance, levonorgestrel which will cause the "morning after pill" to fail to work. The general public is not, of course, aware of this.

[rachel200202]

ok so basically, enzyme induction speeds up the rate of reaction. which means that drugs are metabolised faster.??

[rachel200202]

no i'm not exactly sure what i should be looking for, but if inhibitors slow down the reactions then surely inducers speed them up?? am i on the right lines??

[Asterix]

yep that's right.

[Nik]

Inducers do "speed up" the rate of drug breakdown although the process takes a week to two to take effect, as the liver has to synthesise the enzyme proteins in the first place. Induction is also reversible - once the patient stops taking the drug (or takes a lower dose), synthesis of the inducer enzymes decreases.