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Can't seem to wrap my head around this help is appreciated

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1 I'm trying to understand a pharmacology concept. Specifically, drug half life with peripheral vascular disease (PVD). Stages of drug interaction include: Absorption, biotransformation (elimination), distribution, and excretion.

One question that was on a recent pharmacology exam was the select all that apply. The question read, select all conditions in which a drug dosage would have to be decreased. One of the options was peripheral vascular disease (PVD).

Now, I understand the drug half life concept and I understand the stages of distribution, but I can not understand how PVD would not affect a drugs half life, according to my instructor.

My argument was, PVD reduces blood flow rate, maybe not dramatically, but none the less it does affect blood flow rate @ its occurring site. I assumed, a drug half life to be 48 hours, being 99% protein bound. Under this example I considered the reduction of blood flow @ the PVD site would alter the rate of distribution, thus reducing the rate that would otherwise occur during tissue perfusion: at least this was my argument.

Any explanations of why I am wrong would be appreciated.
PVD may indeed change absorption / elimination / bioavailabilities, but until these are confirmed w/ a clinical study, it's considered a theory... If it's not documented, it's not a definite.To be honest, though, PVD doesn't mean automatically that a person has claudication and significant alteration in blood supply. If PVD is well managed, the person is just like a 100% healthy individual. That said, PVD is equivalent to non-PVD.I can see your point, also, but the decrease if a person isn't having claudication or altered extremity pulses is minimal

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Look where drugs are absorbed simply, not your complicated thought process, gut, small intestine.... then bioabsorbed through liver, kidneys....periphery is not mentioned unless hoffmans elimination which still does not apply to absorbtion. sorry about the spelling, I'm tired. It's been many years since I sat in that class.. but the periphery does not absorb the drug... I'm thinking you're getting too cellular with the process and overthinking it. Please if I'm off base chime in, it's been a while.

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The most common conditions that require dose adjustments involve the kidney and liver. Decreased blood flow is a RESULT of PVD.

Comment:
Drug half life is not affected by PVD. Half life is what it is regardless of how the body distributes it. If drug ABCD has a half life of XX time then just because the body's circulatory system is compromised does not mean the half life changes. Does that make sense?Or did I completely misunderstand your post....been way too long since I have been in school.

Comment:
I think you're overthinking it. Remember nursing school tests are always "pick the BEST answer." Even if PVD theoretically had a tiny effect (which I can see where you're going, but not being a patho or pharm expert, I won't go there), I'm betting there was another answer that was the BEST.
Author: alice  3-06-2015, 16:32   Views: 990   
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