[Research] Phenytoin serum level effective at 3mg/L??

[zx12]

Hi all,

I've come across a lab book. Basic Skills in Interpreting Laboratory Data By Mary Lee. In Google book search. Anyway on page 93 books states that a Whole 50%!! of tonic-clonic seizures are controlled with serum levels of less than 7mg/L!! Just enter "dilantin level less than 10" in google book search to see the preview page for yourself. Now I've never seen anything with these kind of stats before! The neuros seem to be obsessed with that 10-20mg/L number. Being the book is a rather new release 2008, it appears to be trustworty. My question is, can anyone confirm/support or deny these stats? Because, if 50% are controlled <7, & 10% are controlled with a level <3. That 10 number they(neuros) love so much is full of beans!!

[epileric]

I can't confirm or deny those numbers but have you researched the authors to determine their qualifications to make such a claim?

[zx12]

Yes, I checked the books preface. Author appears to be accredited, with a surname of Lee, kind of hard to check too thoroughly. But being listed in Google books also gives some credibility. Thing is Phizers own documentation says effective at lower levels, without giving any number. My point is though, doctors tend to over prescribe & maybe that 10-20 number is not nearly as accurate as believed!! Not that anyone should disregard their doctors instructions, just something to know!

[epileric]

Every books preface will speak highly of the author and being listed by google books or anyone that sells books doesn't say much either.

I checked the contents & pg. 93 is in Chapter 5 which was written by Janis J. MacKichan and Robb McGory. They would be the people to check out.

[zx12]

Robb McGory, Pharm.D., has been named executive associate dean of the College ... Janis J. MacKichan, Pharm.D., accepted the post as chair and professor of ...

The above seem to have more credentials than most! But what is troublesome to me is I've never heard of a Doctor saying a sub 10 level was ok, especially a level less than 7! And if the article is correct, apparently it is ok??

[epileric]

I would definitely ask your neurologist next time you talk to him/her.

also, doing a search for dilantin serum levels I found that medline says for dilantin (phenytoin) is

Phenytoin: greater than 30 mcg/mL

http://www.nlm.nih.gov/medlineplus/e...cle/003430.htm but you might want to see what other medical sites say to see if any contradict that.

[Nakamova]

I don't know about the specific numbers for Dilantin, but in general the suggested range for effective blood serum levels are based on average data. There will always be people at the extremes -- and I tend to be at the low end: When I was on Dilantin, my dose was 90mg/day, my seizures were controlled, and my blood serum levels, taken over the course of my time on Dilantin ranged from 3.0 to 4.7. So I'm proof that a low blood serum level can work.

I'm currently on Lamictal, also at a relatively low dose. In researching dosage for Lamictal I found that there is no established target blood serum level for it -- essentially whatever works for any given patient is that particular patient's target level. (In other words, whatever works, works). And as for a suggested dose, European doctors suggest a much lower range for maintenance dose (100 to 200mg per day) than the U.S. ones do (300 to 500mg). Seems odd that Europeans would need less Lamictal than Americans, doesn't it? And I have seizure control at 175mg/day.

[zx12]

Nakamova, it was seeing 1 of your previous posts that got me researching. There is a real lack of hard numbers out there! because if it is true 50% of tonic-clonics are controlled less than 7, why do none of the docs mention that? Shoot it's hard to get the docs to acknowledge that the dilantin capsule was changed a while back. I'm just looking for the true lower effective level. I've come across some documentation saying a level above 6 may be helpful, but nothing lower than that. Other than the book that caused me to start the thread.

[Nakamova]

I think the Dilantin blood serum numbers from p. 93 of "Basic Skills in Interpreting Laboratory Data" must refer to pediatric patients, not adults. If you take a look at p. 80, you can see a table with the recommendations for Phenytoin (Dilantin):

Adult: 10-20mg
Infant: 6-11 mg

[zx12]

Huh, could be. But it specifically states adult patients in the mentioned numbers paragraph. In fact the article goes on & states the infants numbers after the adults on page 93. That was my reason for starting the thread, to see if there was any collaborating evidence out there. I guess it could be a misprint too? Maybe too, 50% is not considered "strong" enough to be relative? ie. they look for a maybe 60%+ effective rate which would equate to the 10 lower number? But I would think that people who have only a 8 or 9 number might feel better to know those numbers have been proven to work too?

[Nakamova]

Or maybe they could also be referring to "free" phenytoin levels which is typically a much lower number. I'll look at it again tomorrow after I get some sleep...