Leucopenia as an adverse reaction to carbamazepine therapy

Folic acid supplementation reduces the development of some blood cell abnormalities in children receiving carbamazepine

BACKGROUND

Carbamazepine is a commonly used anticonvulsant agent; however, it has been linked with various blood cell abnormalities. This study evaluated the effect of low-dose folic acid supplementation on the prevention of carbamazepine-induced hematological derangements in children.

METHODS

This randomized clinical trial was conducted in children with epilepsy who received carbamazepine monotherapy. Group 1 received carbamazepine alone, and group 2 received carbamazepine plus folic acid. The two groups were age- and sex-matched. Each group comprised 41 children with epilepsy. Complete blood counts were obtained before starting medication (baseline) and then serially. The patients were followed for at least 1 year.

RESULTS

In group 1, 31.4% of the patients developed leukopenia and 17.1% neutropenia, but in group 2, these figures were 14.6 and 9.8% (P = 0.067 and P = 0.331, respectively). At the end of the first year of follow up, white blood cell and polymorphonuclear cell counts were significantly higher in group 2 (P = 0.007 and P = 0.001, respectively). Hemoglobin concentration dropped in group 1, but rose slightly in group 2; these changes were significant. Platelet, lymphocyte, and monocyte counts and changes in serial blood tests did not differ significantly between the two groups.

CONCLUSIONS

Folic acid is a safe drug that can reduce the development of some blood cell abnormalities linked to carbamazepine. It has a favorable effect on preventing the leukopenia and drop in hemoglobin observed in patients receiving carbamazepine, but its exact effect and the optimal dose required to enhance its benefits require further investigation.

A review of carbamazepine's hematologic reactions and monitoring recommendations

Early case reports of fatal hematologic effects attributed to carbamazepine (CBZ) resulted in extensive monitoring recommendations by the manufacturer. The rarity of blood dyscrasias led many authors to question the manufacturer's guidelines. Thus the manufacturer removed specific monitoring guidelines, allowing physicians to monitor CBZ using their clinical judgment. This article reviews case reports and studies of CBZ's hematologic effects. Due to their rapid onset, daily laboratory checks would be necessary to monitor for aplastic anemia, agranulocytosis, and thrombocytopenia. These adverse effects are best monitored by informing patients and physicians to carefully watch for signs and symptoms. Leukopenia develops more slowly, occurring in approximately 12 percent of children and 7 percent of adults. Its onset is typically within the first three months of treatment, with patients at risk having a low or low-normal pretreatment white blood cell (WBC) count. Leukopenia often reverses, even if CBZ is continued. Based upon our review of the literature, we recommend monitoring of those high-risk patients during the first three months of treatment with the frequency being determined by results of each laboratory value. WBC counts less than 3000/mm3 or neutrophil counts below 1000/mm3 warrant a decrease in dose with frequent monitoring or CBZ discontinuation, if necessary.