Q: Lamictal & High Doses
I saw a question that someone had for you about BP and Lamictal-- it addressed
Lamictal at about 100mg or so if I remember.
When I got pregnant I was on 800mg a day. My pdoc wanted me to stay at that
dose, but I couldnt' keep the meds down. I am down to 400mg a day now, but I am
still REALLY concerned about that dose. All the websites I have looked at about
Lamictal being safe are only rated at most at 200mg.
Have you seen ANY research on Lamcital and that high of a dose? I saw another
post here a few minutes ago where you recommeded the person only have up to
Anyway, if you know of ANYONE who would know the complications of such a high
dose, please let me know.
Dear Ms. J' --
In the product information for lamotrigine (the long document the manufacturer
is required by the FDA to make available, which the pharmacist will usually give
you along with the medication; here's an online version for
states that doses up to 700 have been used in epilepsy (page 44 on the scroll
bar) and that for bipolar disorder, doses up to 400 mg were tested but not shown
to be superior to 200 mg.
That's probably where the numbers come from that you
mention above. I have not gone above 400 mg but in a few cases, and there only
to 500, but I hear from other doctors who've gone higher, 800 in one case (and
now yours as well). For people who are also taking carbamazepine (Tegretol,
Carbatrol, Equetro), it would be common to use these much higher doses because
that medication can lower lamotrigine levels by roughly half.
There is a blood test for lamotrigine that would allow
you to get a measure of how much you're actually absorbing and hanging on to,
but we don't get those very often because this is not a medication which
requires tight management of dose and level (compared to lithium for example).
However, you can use that test to see if you're way above common levels. On the
other hand, at this point we still dial the lamotrigine dose to that which is
required to get good symptom control, as long as the patient is not having side
effects from it, up to at least 400 if necessary. Going up to 700 would be
reasonable based on the manufacturer's information, and we commonly go a bit
higher with other medications because the manufacturer generally does not do a
lot of testing to define an "upper limit" we should go by.
From the product information (the document linked
above), I think you can assume that there are quite a few patients with epilepsy
who have had doses in the 400-700 mg range, and that we would therefore have at
least some basis for being able to detect problems with lamotrigine used long
term in that range. Our system is certainly not perfect for detecting long-term
risks of medications like this, but at least you can know that there are people
out there ahead of you who'd been taking doses like this for years. If there's
going to be a major problem, we'd probably be able to detect it before you got
there. Not a great way of determining risk, I grant you. As far as I know, there
is not another way of determining risk, so I can't refer you to another source
(any one person can easily have a wrong impression, either positive or negative,
based on their own experience; what we need are large groups and years of
experience with higher doses. I suppose you could try to find a neurologist
who's used those kinds of doses for years and confirm with her/him that there
have been no lasting or severe consequences of using those amounts. As you can
see, I hope that information, as much as we can gather, is an antidote of sorts
to the understandable anxiety of having to take medications like this.
Published September, 2005