Phenytoin loading dose

airbornemedic11

airbornemedic11

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Hmm? OK, this is a homework question and I've spent way too much time researching it. Yes I've searched on this forum already. What is the loading dose of phenytoin? I'm familiar with the cardiac drugs, but is there an equation that is taught to paramedics regarding loading doses. Seems like every drug will be different since it involves bioavailability of the drug. And most of the stuff I'm finding is nursing or MD lectures. Anyway.

The pt is 100kg, stopped taking his phenytoin 3 weeks ago, but resumed taking it last night and had a seizure today. That's all the info. What is the loading dose?
Thanks.
 
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airbornemedic11

airbornemedic11

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Yeah, Ive seen that. What's the target dose? What's the current level? I'm guessing current level is 0? He hasn't taken his meds in 3 weeks. I'm guessing his ht is 70 in, don't know if it matters? Maybe a BMI thing? It says to assume target is 1-2mcg. Why? What is the equation involved?
 
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airbornemedic11

airbornemedic11

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Man that is a crazy equation. Ideal body wt? Ht over 60 inches? Goal free phenytoin? I'm still in paramedic class. Is this taught in a text book somewhere? We're using Caroline's book. I don't see it anywhere in there. Seems like a question just to make us do some in depth research on a protocol I'll never use, at least not as a paramedic. Are there any medics out there who have used this equation?
 
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Nova1300

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A few random facts about this drug:

1. It is a cause of drug-induced fever. Especially if the drug was recently started. In patients with unexplained fever, negative cultures and no good cause of infection, you frequently start searching through the drugs. This guy is a culprit
2. It is a known teratogen.
3. It can cause Steven-Johnson and toxic epidermal necrolysjs Both worth looking up if you haven't heard of them.
4. Patients with low plasma protein levels get toxic on it. Liver disease, malnutrition, patients with inflammatory response, all lose plasma protein. Most of the drug is bound to proteins and doesn't do much. But when not bound, it exerts it's clinical effects. Patients with low protein levels have a lot more free (active) drug.
5. Some drugs have an even stronger affinity for proteins. These drugs will bump the phenytoin off the protein and take its place. That leaves a lot more drug unbound, and active.
6. It can be a cause of DRESS syndrome
6. I have worked with several people, 2 from Colorado, who pronounce it:
Phe-net-oh-win
7. Overall, a drug with a lot of side effects and a moderate evidence behind it.


-Bored on a Saturday night
 
ExpatMedic0

ExpatMedic0

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I had no idea Dilantin had so many side effects. Good info
 
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