Fatal pancytopenia during high-dose valproate monotherapy

Hematological Consequences of Valproic Acid in Pediatric Patients: A Systematic Review with a Mechanistic Approach

PURPOSE

Although valproate (VPA) has several advantages in controlling seizures, it may cause serious hematological consequences. Hematotoxicity of VPA is particularly important in pediatrics because patients at this age are at a growing risk of leukemia. For a conclusive agreement about the toxicity of VPA, in this study, we systematically reviewed the literature in which the hematological consequences of VPA had been emphasized. <P> Methods: A systematic literature search was performed in June 2021 on electronic databases to find original research on the association between VPA therapy and hematotoxicity in pediatric patients. For this purpose, the following search terms "hematotoxicity", "valproic acid" and "pediatrics" with different spellings and similar terms, were searched in the title, keywords, and abstracts of articles. The data were collected and used for qualitative data description. <P> Results: A total of 36 relevant articles with an overall 1381 study population were included. The results showed that VPA could cause severe hematotoxicity in children even at therapeutic doses. Neutropenia, thrombocytopenia, and bone marrow depression are the most common complications associated with VPA therapy. Also, findings showed that after discontinuation of VPA and starting other antiepileptic drugs or reducing the administered VPA dose, hematologic damages were entirely resolved, and all the hematological parameters improved during two weeks. <P> Conclusions: This review showed that VPA therapy could cause hematotoxicity in children; hence, it is recommended to monitor hematological indices during VPA therapy. Also, according to the suggested mechanistic pathways of VPA side effects, a combination of VPA with antioxidants may reduce hematological side effects.

Valproic acid and fatalities in children: a review of individual case safety reports in VigiBase

INTRODUCTION

Valproic acid is an effective first line drug for the treatment of epilepsy. Hepatotoxicity is a rare and potentially fatal adverse reaction for this medicine.

OBJECTIVE

Firstly to characterise valproic acid reports on children with fatal outcome and secondly to determine reporting over time of hepatotoxicity with fatal outcome.

METHODS

Individual case safety reports (ICSRs) for children ≤ 17 years with valproic acid and fatal outcome were retrieved from the WHO Global ICSR database, VigiBase, in June 2013. Reports were classified into hepatotoxic reactions or other reactions. Shrinkage observed-to-expected ratios were used to explore the relative reporting trend over time and for patient age. The frequency of polytherapy, i.e. reports with more than one antiepileptic medicine, was investigated.

RESULTS

There have been 268 ICSRs with valproic acid and fatal outcome in children, reported from 25 countries since 1977. A total of 156 fatalities were reported with hepatotoxicity, which has been continuously and disproportionally reported over time. There were 31 fatalities with pancreatitis. Other frequently reported events were coma/encephalopathy, seizures, respiratory disorders and coagulopathy. Hepatotoxicity was disproportionally and most commonly reported in children aged 6 years and under (104/156 reports) but affected children of all ages. Polytherapy was significantly more frequently reported for valproic acid with fatal outcome (58%) compared with non-fatal outcome (34%).

CONCLUSION

Hepatotoxicity remains a considerable problem. The risk appears to be greatest in young children (6 years and below) but can occur at any age. Polytherapy is commonly reported and seems to be a risk factor for hepatotoxicity, pancreatitis and other serious adverse drug reactions with valproic acid.

Successful reintroduction of valproic acid after the occurrence of pancytopenia

BACKGROUND

Valproic acid is associated with a variety of hematologic abnormalities, most commonly thrombocytopenia. Pancytopenia is much less common and potentially much more serious. Little is known about the natural course of valproate-induced pancytopenia.

CASE SUMMARY

We present a patient who developed pancytopenia while taking valproic acid for bipolar illness. After failing to respond to several other mood stabilizers, valproic acid was cautiously reintroduced with close hematologic monitoring. The pancytopenia has not recurred in the past 6 months.

CONCLUSIONS

Pancytopenia may not represent an absolute contraindication to continuing valproate therapy, although caution is warranted.

Valproate-associated coagulopathies are frequent and variable in children

PURPOSE

Valproic acid (VPA) is an antiepileptic drug (AED) commonly used for generalized and focal epilepsies. The clinical relevance of coagulopathies, known as side effects of VPA therapy, especially thrombocytopenia, von Willebrand disease, and a decrease of factor XIII, is still unclear.

METHODS

In our institute, we noticed a high incidence of clinically relevant coagulation problems related to VPA in eight patients within 1 year only and a further seven children with significant coagulopathy were identified in the context of planned surgery.

RESULTS

We provide an overview of these patients and all six VPA-induced coagulopathies.

CONCLUSIONS

At this time, it cannot be recommended to control all hemostatic parameters in every patient. Whenever an increased bleeding tendency is observed, or before surgical procedures, a platelet count, thrombelastography, prothrombin time, activated partial thromboplastin time, TT, fibrinogen, von Willebrand factor, and factor XIII should be examined. With 385 VPA-treated patients per year and 15 cases of coagulation disorders in this period, we estimate the incidence of coagulation disorders related to VPA in children to be nearly 4%.

Valproate-associated dysmyelopoiesis in elderly patients

Sodium valproate is widely prescribed for patients with epilepsy and psychiatric disorders. Hematologic toxic effects have been largely described in pediatric patients, and dysmyelopoiesis is reported rarely. We describe 2 elderly patients with valproate-associated dysmyelopoiesis and postulate that this particular side effect may be much more common than currently recognized. A correct diagnosis is important for acute patient anagement and for prognostication.

Temporary pure red-cell aplasia during valproate monotherapy: clinical observations and spectral electroencephalographic aspects

We report the case of a 4-year-old boy with pure red-cell aplasia associated with sodium valproate monotherapy. Treatment with valproate was initiated because of idiopathic tonic-clonic seizures; he became free of seizures. During the introduction of and ongoing antiepileptic drug treatment, clinical and laboratory controls using electroencephalographic (EEG) spectral analysis were performed at regular intervals and disclosed normal values. Ten months after the introduction of valproate, clinical examination was normal except for marked pallor. Peripheral blood showed macrocytic anemia and the bone marrow finding was isolated absolute erythroblastopenia. At the same time, significant changes in EEG background activity were present as well-defined slowing. There was an increase in the relative power of theta activity and a decrease in alpha 2 activity in the occipital regions. Valproate was discontinued and phenobarbital therapy introduced. A complete resolution of the hematologic damage was observed after valproate withdrawal. Recovery of the hematologic parameters started 14 days after discontinuation of valproate therapy, while normalization of EEG background activity was observed earlier. The patient maintained stable hematologic values and seizure control without disturbances of the spectral EEG. After 6 months of phenobarbital therapy, re-administration of sodium valproate was not followed by recurrence of any clinical or electrophysiologic symptoms or abnormalities.

Hematologic toxicity of sodium valproate

PURPOSE

Sodium valproate is a commonly used anticonvulsant in the management of childhood refractory epilepsy with good response rates and acceptable toxicity. Hepatotoxicity is the most widely recognized toxicity. With the use of higher drug levels to achieve adequate seizure control, hematologic toxicity is being increasingly encountered, and the pediatric hematologist is consulted for these problems in the pre- or perioperative setting. The purpose of this article is to characterize the various hematologic toxicities encountered in a clinical setting and to provide guidelines to assist in the management of these patients.

METHODS

A literature review was undertaken to identify the hematologic toxicities of valproate used as monotherapy or polytherapy. Key words used in the search were valproate, hematology, and bleeding.

RESULTS

Valproate can cause direct bone marrow suppression leading to aplastic anemia or peripheral cytopenia affecting one or more cell lines. Occasional fatal bone marrow failure, myelodysplasia, and a clinical picture resembling acute promyelocytic leukemia have also been seen. Thrombocytopenia, macrocytosis, neutropenia, and pure red cell aplasia can occur but are not reported to be life-threatening. A bleeding diathesis associated with valproate use may include thrombocytopenia, abnormal platelet function, and acquired von Willebrand disease type I.

CONCLUSIONS

Hematologic toxicities of valproate are common, vary in onset and severity, are recurrent, transient, or persistent, and usually occur with a serum valproate level greater than 100 microg/mL. In most situations, even when highly clinically significant, they can be reversed with dosage reduction; drug discontinuation is rarely required. Potential adverse effects such as thrombocytopenia and leukopenia are easily detected by laboratory monitoring, which should be continued indefinitely at least on a quarterly basis. Caution for elective surgery is advised; preoperative coagulation studies should be done, including platelet function studies and von Willebrand factor levels. Perioperative use of DDAVP to increase von Willebrand factor levels and improve platelet function is appropriate in some cases.

A cellular model for drug interactions on hematopoiesis: the use of human umbilical cord blood progenitors as a model for the study of drug-related myelosuppression of normal hematopoiesis

A cellular model of hematopoiesis which would be more convenient than bone marrow (BM) progenitors and directly relevant to human pathology is needed in order to investigate xenobiotic toxicity. Human umbilical cord blood (HCB), previously shown to be able to repopulate BM, provides a powerful in vitro model of normal human hematopoiesis. In order to validate the use of normal HCB progenitors as targets for dose-related myelosuppression, we used clonogenic assays and expansion in a liquid culture of progenitor-enriched cell suspensions from HCB. A series of 8 reference molecules, doxorubicin, cytosine-arabinoside, 5-fluorouracil, 3'-azido-3'-deoxythymidine, acetylsalicylic acid, sodium valproate and two cephalosporin antibiotics, were tested. In vitro 50% inhibition concentrations (IC50) were compared to those observed or reported with BM progenitors, and to the values of plasma concentrations from treated patients. HCB progenitors as in vitro targets for cytotoxic molecules were easy to access and handle, and their use was sensitive, specific and reproducible. They gave results similar to BM progenitors and allowed a qualitative approach to cellular metabolism and toxicity using morphological, flow cytometric and chromatographic methods.

Delayed peak serum valproic acid in massive divalproex overdose--treatment with charcoal hemoperfusion

BACKGROUND

Increased clearance and apparent clinical improvement in valproic acid overdose has been reported following in-series hemodialysis/hemoperfusion therapy. We report a case of divalproex sodium and chlorpheniramine overdose treated with charcoal hemoperfusion and multiple-dose activated charcoal.

CASE REPORT

A 32-year-old female presented alert three hours postingestion of her own medication. Serum valproic acid was 105 micrograms/mL. No anticholinergic toxicity was seen. Despite three doses of activated charcoal over 14 hours, serum valproic acid continued to rise. Whole bowel irrigation and multiple-dose activated charcoal were commenced 17 h postingestion when serum valproic acid was 1380 micrograms/mL. Charcoal hemoperfusion was instituted three hours later when serum valproic acid had not fallen and the patient remained obtunded.

RESULTS

Initial extraction ratio of the hemoperfusion cartridge was 0.54 with plasma clearance of 54.5 mL/min. Valproic acid elimination half-life was 3 h during the 190 min hemoperfusion cycle. Posthemoperfusion elimination half-life was 4.8 h with continued multiple-dose activated charcoal dosing. The clinical condition improved during hemoperfusion.

CONCLUSION

Enteric coated valproic acid preparations may cause delayed toxicity in overdose, particularly with coingested anticholinergic medications. In our case, charcoal hemoperfusion appeared to increase valproic acid clearance.

Haematological disturbances during long-term valproate therapy

A 14-year-old boy with mental retardation presented with severe thrombocytopenia, macrocytic anaemia and allergic dermatitis. He had been treated with valproate for seizures since the age of 2 years. Clinical examination showed severe purpura, mucous bleeding and extensive dermatitis. Tests to detect serum direct antiplatelet antibodies were positive and bone marrow examination revealed myelodysplastic abnormalities. Valproate was discontinued and both dermatitis and general condition of the child improved with normalization of the full blood count. This report suggests that valproate may produce both peripheral immune thrombocytopenia and severe bone marrow depression several years after the initiation of the therapy.