Clozapine Augmentation with Lamotrigine

It is refreshing to see something like this.  Both drugs are
available as generics, so the financial motivation for a study like
this is not great.  But the clinical benefit could e substantial,
albeit for a small subset of patients.



Clozapine is considered to be the most efficacious antipsychotic
medication, in that it is the drug to which the highest percentage of
persons with psychosis have a positive response.  It is, however,
considered a third-line drug.  The reason is that about 1% of
patients will develop severe granulocytopenia.  So, in general, a
patient will be tried on at least two different antipsychotic
medications before undergoing a trial of clozapine.  It generally
is used for treatment of schizophrenia, but may be used also for
bipolar disorder, or variants of those two conditions.



Even though clozapine is the most efficacious antipsychotic, many
patients are left with significant residual symptoms.  What then?

In such a situation, you can 1) do nothing, 2) increase the dose ,
3)decrease the dose, (including decrease to zero) 4) switch to a
different medication, or 5) add another medication.  Option #1 may
be feasible, but often is not a practical option.  Option #2 makes
sense, up to a point, but there there is a limit.  Once you reach
the limit, you have to chose one of the other options.  Option #3
rarely makes any sense, assuming that a proper titration schedule was
followed.  Option #4 may make sense, but remember, by the time a
patient is on clozapine, it is unlikely that a different antipsychotic
medication would be helpful.  So, usually Option #5 is the right
one.



People have tried augmentation (adding a second medication to add to
the effect of the first) with a variety of substances.  Depakote
often is a good one.  The thing is, clozapine tends to carry with
it a heavy burden of adverse effects.  Depakote may add to that
burden.  Same with lithium.  Some will add a first- or
second-generation antipsychotic, but I've never been a fan of that
approach.  Occasionally, I've gotten lucky with oxcarbazepine or
an antidepressant.  Once, I got lucky with
clozapine+oxcarbazepine+venlafaxine. 



Now, there is a meta-analysis that shows reasonably well-proven
efficacy of augmentation with lamotrigine.  This is attractive,
because most persons won't get a big increase in the adverse effect
burden.



The meta-analysis was done by the Cochrane group.  There is an
open-access synopsis published in Current Psychiatry online.  (You
may have to register, which is free, and I think is open to anyone, but
I am not 100% sure of that.)

href="http://www.currentpsychiatry.com/article_pages.asp?AID=7167">When
Clozapine is not enough: Augment with lamotrigine?



Current antipsychotics are reasonably effective in treating positive
symptoms, but they do less to improve the negative and cognitive
symptoms that contribute to patients' long-term poor functional
capacity and quality of life. So what do psychiatrists do in clinical
practice to mitigate antipsychotics' limitations? We augment.



Schizophrenia patients routinely are treated with polypharmacy--often
with antidepressants or anticonvulsants--in attempts to improve negative
symptoms, aggression, and impulsivity. Most adjuncts, however--including
divalproex, antidepressants, and lithium--have shown very small,
inconsistent, or no effects. The only agent with a recent meta-analysis
supporting its use as augmentation in treatment-resistant schizophrenia
is lamotrigine, an anticonvulsant approved for use in epilepsy...

The authors add a few points.  High doses may be required, greater
than 200mg.  This augmentation strategy may help with residual
negative symptoms, even if positive symptoms are adequately
controlled.  There was some evidence for improvement in cognitive
symptoms as well.



The article goes into some detail about a hypothesis regarding the
effects on glutamate transmission.  While interesting, it is not
yet established very well.



Probably, most general psychiatrists would have only a few patients for
whom this augmentation strategy might be appropriate.  Also, both
medications carry serious risks, so it is important that the
practitioner be well-versed in psychopharmacology prior to undertaking
this strategy.  Even so, it is a welcome development.