Q: Lithobid SR & Lithium Carbonate
My son was dxed with Bipolar Disorder when he was 6 years old, he is
now 12. My question is about one of the meds he takes: Lithobid SR
300 mg. tabs. He had a very bad experience when the pharmacy (and
the insurance) substituted lithium carbonate for the brand Lithobid that he had
been taking. He became very withdrawn, depressed, sensitive to sound of
any kind and could not sleep. He was very agitated, and could not sit down
or stop moving, all day and all night. By the time I realised something
was terribly wrong, he was having suicidal thoughts. Has anyone ever
experienced this before? His lithobid is slow release, is that the
difference? Why is this med. delivery different from the generic?
We are sticking with brand-name only from now on. Would appreciate
any info you have,
Dear Vickie --
I haven't seen that kind of change when my patients shift from slow-release to
non-slow-release (just to make things a bit more complicated, there's now a
generic slow-release. With it too, I've not seen a problem, yet -- it's been
less than a year so far-- in patients switching from Lithobid to generic
slow-release). Not to say that generics are always okay. There are case reports
of problems when patients switch from Clozaril to generic clozapine; and one of
my patients had a crystal-clear "didn't work the same" experience switching to a
generic nefazodone from Serzone.
So, could it be that the difference between the two, for your son, is the
slow-release mechanism, versus the immediate release of lithium carbonate? I can
imagine several reasons for this, although if they were true one would think
we'd see this problem more often (for example, I often switch from Lithobid, or
now from the generic slow-release, to regular lithium carbonate, to decrease
problems with diarrhea, which are well-recognized to be associated with the
slow-release version more so than with lithium carbonate).
First, one could imagine that your son actually absorbs more lithium from the
slow-release, for some reason. If you ever had to figure this out, you could
check this possibility by looking at his blood level (although it would be a bit
tricky working with his doc' to figure out just when to measure his level in
order to fairly compare the two, as they "peak" at different times and that
could artificially make for quite a difference).
Perhaps even more likely though still just theoretical, would be to figure
that your son "needs" a higher blood level of lithium to be sustained around
the clock. Lithium carbonate (that is, the generic non-slow-release) has a
rather large "peak" and then a very large dip in blood levels. They are far from
constant over 24 hours. The slow-release version makes lithium peaks lower and
troughs less deep. Maybe somehow these peak/trough relationships really matter
for your son.
Just guessing, mind you, in case it somehow turned out to be useful; as I've
not seen this myself (will keep my eyes peeled a bit wider perhaps, after your
note), I can't offer anything more solid.
Published July, 2004