Nclex Practice

[Student RN123]

hello all,

i came across an nclex practice question and now i am stuck. can someone help explain and choose which would be the appropriate answer.

the majority of drug metabolism is catalyzed by the cytochrome p-450 group of enzymes......when these enzymes are inhibited, a drug simultaneously given will

a. reach higher-than-intended levels in the body.

b. be inhibited and levels in the body will drop.

c. have no effect in the body.

d. create the potential for anaphylaxis.

[NewNurseyGirl2009]

Not a nurse but a cna here but let me see I think I understand. If the p-450 enzymes are catalyzing the drug and that drug is inhibited there is nothing to catalize or control the drug and therefore it just builds up. Hence there is more.

[Daytonite, BSN, RN]

the majority of drug metabolism is catalyzed by the cytochrome p-450 group of enzymes......when these enzymes are inhibited, a drug simultaneously given will

a. reach higher-than-intended levels in the body

.

b. be inhibited and levels in the body will drop.

c. have no effect in the body.

d. create the potential for anaphylaxis.

the answer is (a).

the stem of the question is dazzling you with lots of medical terminology in an attempt to confuse you.

so, define the terms and reread the question. . .catalysis is the speeding up of a chemical reaction. in this case, the root of the question is telling you that the majority (almost all) of drug (any medicinal substances) metabolism (chemical transformation once taken into the body) is catalyzed (speeded up) by cytochrome p-450 group of enzymes (an intimidating name for some enzymes, isn't it? enzymes are proteins that alter the rates of chemical reactions........when these enzymes (oops, what happened to the fancy, intimidating name?) are inhibited (prevented from doing what the stem of the question told you in the first sentence--speed up the chemical reaction), a drug (any medicinal substance) simultaneously (at the same time) given will.....would it be better if the question had been worded this way?

• the chemical transformation of most drugs is accelerated by the cytochrome p-450 group of enzymes. what will happen to a drug that is given at the same time that the normal function of these enzymes is being inhibited?

what you must understand is that metabolizing drugs is how the body breaks down and gets the drugs out of the body, usually through the gi track or the kidneys. so if that process is being slowed down, then the effect of the drug is going to remain in the body longer than intended. here is the reasoning on the answer choices:

a. reach higher-than-intended levels in the body

.

the drug will be metabolized at a very slow rate so that the active drug will remain in the body a longer time to exert its effects. it will also create higher drug levels than intended.

b. be inhibited and levels in the body will drop.

this is exactly opposite of what should happen.

c. have no effect in the body.

this is not true. the drug will be metabolized at a very slow rate.

d. create the potential for anaphylaxis.

here again you need to know medical terminology. they are trying to trick you into thinking that anaphylaxis might be the opposite of catalysis. anaphylaxis is, in fact, an allergic reaction that occurs when there is hypersensitivity to a drug. that has absolutely nothing to do with enzyme activity and drug metabolism. this is an answer choice that is right out there in left field!