By Marcello Cherchi, MD PhD
For patients
Oxcarbazepine is sometimes used for treating vestibular paroxysmia and vestibulo-cochlear paroxysmia. Up to 10% of patients stop the drug because of a rash.
For clinicians
Practical summary
Oxcarbazepine is an anti-epileptic medication whose main mechanism of action is blockade of voltage-gated sodium channels. The adverse effect that most commonly leads to discontinuation of the drug is a skin rash, which occurs in up to 10% of patients; other adverse effects include fatigue, headache and hyponatremia. The main application of oxcarbazepine in otoneurology is in the management of vestibular and vestibulo-cochlear paroxysmia.
Introduction
Oxcarbazepine is a 10-keto homologue of carbamazepine (Lloyd et al. 1994; Shorvon 2000).
was originally used as an anti-epileptic against partial and generalized tonic-clonic seizures (McLean et al. 1994).
Pharmacology
Oxcarbazepine is almost completely hepatically metabolized to its active metabolite, a 10-monohydroxylated derivative (MHD) (Lloyd et al. 1994; Shorvon 2000), and “the majority of the pharmacologic activity can be associated with MHD” (Lloyd et al. 1994).
Oxcarbazepine appears to have several mechanisms of action. The main mechanism is blockade of voltage-gated sodium channels (McLean et al. 1994), “resulting in stabilization of hyper-excited neural membranes, inhibition of repetitive neuronal firing and inhibition of the spread of discharges” (Shorvon 2000). Other possible, though less significant, mechanisms include an effect on potassium channels (McLean et al. 1994).
Adverse effects
The adverse effects of oxcarbazepine are “similar in nature to that of carbamazepine, although the frequency and severity of the side-effects have been shown to be less” (Shorvon 2000).
Of these, “The commonest dose-related side-effects are fatigue, headache, dizziness and ataxia” (Shorvon 2000). In addition, “Skin rash is relatively common (up to 10% of all patients) and is the main reason for discontinuation of the drug” (Shorvon 2000).
One adverse effect of oxcarbazepine is hyponatremia, which is thought to be secondary to an anti-diuretic hormone-like effect (Shorvon 2000). The hyponatremia is “usually mild” and “in routine clinical practice, serum sodium need not be monitored” (Shorvon 2000).
Cautions and contraindications
The available data on the use of oxcarbazepine in pregnancy are insufficient to draw firm conclusions (Montouris 2005), so we generally recommend refraining from the use of oxcarbazepine during pregnancy and lactation.
Relevance in otoneurology
The main application of oxcarbazepine in otoneurology is in the management of vestibular and vestibulo-cochlear paroxysmia.
References
Lloyd P, Flesch G, Dieterle W (1994) Clinical pharmacology and pharmacokinetics of oxcarbazepine. Epilepsia 35 Suppl 3: S10-3. doi: 10.1111/j.1528-1157.1994.tb05938.x
McLean MJ, Schmutz M, Wamil AW, Olpe HR, Portet C, Feldmann KF (1994) Oxcarbazepine: mechanisms of action. Epilepsia 35 Suppl 3: S5-9. doi: 10.1111/j.1528-1157.1994.tb05949.x
Montouris G (2005) Safety of the newer antiepileptic drug oxcarbazepine during pregnancy. Curr Med Res Opin 21: 693-701. doi: 10.1185/030079905×43640
Shorvon S (2000) Oxcarbazepine: a review. Seizure 9: 75-9. doi: 10.1053/seiz.2000.0391
