Oxcarbazepine

Additional information

Pharmacokinetics and dosing

According to the pharmaceutical company, no sex-related pharmacokinetic differences have been observed in children, adults or the elderly [1, 2]. Pharmacokinetic studies in Chinese patients with epilepsy show contradictory results. One study involving children and adults (54 men, 24 women, mean age 37 years) found lower clearance of the active metabolite 10-monohydroxy derivative (MHD) in women than in men [3], while a study including only children (90 boys, 51 girls, mean age 8 years) did not find an association between MHD pharmacokinetics and patient’s sex [4].

Effects

The pharmaceutical company report that no important sex differences in the efficacy of oxcarbazepine in epilepsy patients were shown in clinical trials [2, 5]. No other published studies with a clinically relevant sex analysis regarding the effects of oxcarbazepine have been found.

Adverse effects

Adverse events were reported more frequently in women than men treated with carbamazepine or oxcarbazepine for treatment of trigeminal neuralgia or neuralgiform (36 men, 43 women). The probability of a toxic dose with oxcarbazepine for women were around 1200 mg and for men around 1800 mg [6].

Oxcarbazepine can induce hyponatremia and women may have a higher risk than men of developing hyponatremia. A suggested explanation to this might be sex-related differences in the mechanisms of sodium transport [7]. A register-based study in epilepsy patients (69 men, 289 women) showed that women treated with oxcarbazepine had a higher risk of hyponatremia than men (odds ratio 2.25) [8].

Reproductive health issues

The plasma concentrations of estrogens and progestogens may be decreased by coadministration of oxcarbazepine. The effect of hormone therapy may therefore be impaired [2]. Regarding drug-drug interactions aspects, please consult Janusmed Interactions (in Swedish, Janusmed interaktioner).

There are studies indicating that treatment with oxcarbazepine (as well as carbamazepine and valproic acid) is associated with sperm abnormalities in men with epilepsy [9-12]. The clinical relevance of this finding is unclear. However, it is possible that the epilepsy itself affect the sperm quality, since decreased levels have been seen even before AED treatment [13]. Semen quality, sexual function and sex hormones in men with epilepsy are not affected by treatment with lamotrigine, levetiracetam, or oxcarbazepine, according to a randomized controlled trial including 38 adult men with newly diagnosed epilepsy [13]. Reports of sexual dysfunction caused by levetiracetam or oxcarbazepine are limited to case reports. Larger studies suggest that lamotrigine, levetiracetam and oxcarbazepine can improve sexual function [13, 14]. 

Regarding teratogenic aspects, please consult Janusmed Drugs and Birth Defects (in Swedish, Janusmed fosterpåverkan).

Other information

Slightly more men than women were treated in inpatient care with the main diagnosis epilepsy (ICD-10 G40) in Sweden during 20192011, totally 2 8553389 men and 2 5592921 women. The prevalence was highest among the elderly in both sexes. In the age group 5045 year and older, the diagnosis was on average 1.31.4 times more common among men. In the younger age groups, the prevalence was similar in both women and men [15]. In a Swedish study, the incidence of unprovoked epileptic seizures/epilepsy was generally higher among men than women, especially in the age group 60 years and older. In the age group 1-9 year, the incidence was higher among girls [16].