Acute oxcarbazepine overdose in an autistic boy

Chronic oxcarbazepine intoxication in a patient with primary antiphospholipid syndrome on maintenance haemodialysis

WHAT IS KNOWN AND OBJECTIVE

Oxcarbazepine (OXC) is an antiepileptic drug. Patients suffering from chronic kidney disease with an estimated glomerular filtration rate below 30 ml/min/1.73 m² require dose adjustments for OXC.

CASE SUMMARY

A 31-year-old man was admitted with a history of diplopia, ataxia and dizziness attacks that had disappeared after a regular haemodialysis sessions for three months. Medical history was remarkable for primary antiphospholipid syndrome (APS). However, no signs of new-onset APS-related neurological involvement were present. Then, it was revealed that the patient had been using 2400 mg/day of OXC for four months, despite the prescription of half of this dose. Serum OXC level was 50 mcg/ml (reference: 3-35 mcg/ml) before a regular haemodialysis session. All symptoms disappeared in a few days after reducing to 1200 mg/day and never recurred.

WHAT IS NEW AND CONCLUSION

We reported a chronic OXC intoxication in a patient on maintenance haemodialysis. To the best of our knowledge, it is the first chronic OXC intoxication case in the literature. It could be related to episodic removal of OXC and its metabolites via haemodialysis. Consequently, dose modification of drugs is a pivotal point in haemodialysis patients. Chronic drug intoxications must be kept in mind in haemodialysis patients with unexplained symptoms.

Thirteen years of oxcarbazepine exposures reported to US poison centers

Objectives:

Oxcarbazepine (OXC) is a 10-keto analogue of carbamazepine used in patients with partial and secondary generalized seizures. We evaluated ingestions of OXC reported to US poison centers for adverse effects from supratherapeutic doses and/or overdose.

Method:

Retrospective analysis of data reported to National Poison Data System from single-substance OXC ingestions between January 2000 and December 2012.

Results:

There were 18,867cases with a mean of 1451 exposures/year. The patients were predominantly adults with 5464 exposures in children <6 years (29%). The most commonly reported clinical effects were drowsiness ( n = 4703, 25%), vomiting ( n = 1559, 8%), tachycardia ( n = 590, 3%), agitated ( n = 342, 1.8%), hypotension ( n = 178, 0.9%), electrolyte disturbance ( n = 153, 0.8%), coma (n = 156, 0.8%), and seizures ( n = 121, 0.6%). There were 176 patients with a major effect of which 31 involved were children and 1728 (9%) patients with moderate effects of which 300 involved were children. Five deaths were reported in adults. Intentional exposure (e.g. suicide) was the reason for exposure in 68% of patients with major effects and in all fatalities. Fifty-three percent of adults and 38% of children were managed in a health-care facility (HCF). HCF utilization levels remained consistent.

Discussion:

Severe outcomes appear to be infrequent (<1%). Unlike other anticonvulsants OXC does not appear to be proconvulsant in overdose.

Conclusion:

Serious outcomes for OXC overdoses are unlikely in the pediatric patient. With only mild symptoms likely, observation at home may be appropriate for the majority of cases. In the adult population there appears to be few neurologic and cardiovascular complications even in the intentional exposure.

[Therapeutic drug monitoring of oxcarbazepine]

Oxcarbazepine is an analogue of carbamazepine, used for the treatment of partial seizure with or without secondary generalization. The two forms R and S of the mono-hydroxylated derivatives (MHD) are responsible for most of the anti-convulsant activity and it is the concentrations of MHD that are relevant in therapeutic drug monitoring (TDM). Analysis of currently literature provides no well-established relationship between plasma concentration of MHD and efficiency or toxicity. Although there is not a validated therapeutic range, the residual concentrations of usually observed therapeutic MHD are situated between 12 and 30 mg/L. In certain pathological or physiological circumstances, the pharmacokinetic variability of the oxcarbazepine can be considerable, but this strong unpredictability does not nevertheless justify the TDM of the MHD. Based on the available evidence, TDM of MHD is not routinely warranted but may be possibly useful in specific situations such as pregnancy or renal insufficiency.