Leukopenia, carbamazepine-induced

The combination of lithium with an anticonvulsant mood stabilizer can be beneficial. There have been reports of lithium/carbamazepine neurotoxicity, but on the other hand, lithium can benefit carbamazepine-induced leukopenia. There do not appear to be clinically important pharmacokinetic interactions of lithium with gabapentin... 

Some interactions between lithium and other drugs are beneficial. In approximately 60% of depressed patients in whom conventional treatment has failed, the combination of lithium and antidepressant drugs proves successful where neither drug was effective alone (190, 193, 196, 197). Combinations of lithium and carbamazepine are also increasingly used in the successful treatment of refractory affective illness (198). This combination is generally safe, though the possibility of neurotoxicity should be considered. One additional potential benefit of the use of lithium in this way is the prevention of leukopenia induced by carbamazepine (199). Inosotol phospholipid metabolism is not affected by carbamazepine, suggesting an alternative locus of action from that of lithium (200). 

Low levels of serum folate are often associated with low levels of erythrocyte folate (intracellular). The mean corpuscular volume (MCV) of erythrocytes may increase slightly with low folate levels, though overt macrocytic anaemia occurs infrequently. Carbamazepine (CBZ) therapy may cause leukopenia and neutropenia. In a randomized trial in patients on CBZ, subjects on folic acid had higher leucocyte counts and less neutropenia compared with subjects without vitamin supplements. Other studies found no connection between folate and AED-induced haematological abnormalities. 

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