A preliminary observation of the adverse effects of phenobarbital among patients with convulsive epilepsy in rural West China.

BACKGROUND

This study explored the adverse effect (AE) profile of phenobarbital (PB) among patients with active convulsive epilepsy (ACE) from resource-poor areas.

METHODS

Patients with ACE were enrolled into an epilepsy management project in rural West China. Information was obtained from monthly follow-up questionnaires. The demographic and clinical features of the patients with AE were firstly described. After that, the occurrence rate was estimated for each subtype of AE at three different severity levels (mild, moderate, and serious). Survival analysis was used to determine the potential risk factors of AEs.

RESULTS

A total of 7231 patients (3780 men) were included in the present cohort. During the follow-up time period (average 33.4months), the most common AEs were drowsiness (moderate: 4.4%, serious: 0.68%), dizziness (moderate: 3.7%, serious: 0.5%), and headache (moderate: 2.9%, serious: 0.41%). In the confirmed AE groups (moderate and serious severity levels), the symptoms tended to be transient, with durations of less than 3months. Polytherapy was an independent risk factor for AEs and had an increasing risk when the severity of the AE increased (Hazard Ratio 1.12, 1.55, and 2.52 for mild AE, moderate AE, and serious AE, respectively). Receiving a high dosage of PB (>180mg/day) indicated a slightly elevated risk (Hazard Ratio 1.22 and 1.27 for mild AE and moderate AE, respectively).

CONCLUSION

Phenobarbital demonstrates overall tolerability, and serious AEs were not common. Patients receiving a high dose of PB or polytherapy are at increased risk of developing AEs.