Primidone, an anticonvulsant, is one of the medicines that can lead to folate deficiency. So if you take primidone, your body may run low on folate, which is the vitamin that 6s-5-Methyltetrahydrofolate [Bio-Active Folate] supplies.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.