Influence of folic acid on blood-phenytoin levels
Baylis, E.M.; Crowley, J.M.; Preece, J.M.; Sylvester, P.E.; Marks, V.
Lancet 1(7689): 62-64
1971
ISSN/ISBN: 0140-6736 PMID: 4099219 Document Number: 32770
Blood was obtained from 175 epileptics given long. term anticonvulsant treatment with different com. binations of phenobarbitone, phenytoin and primidone, from 25 epileptics given no anticonvulsant treatment, and from patients with low red cell folacin before and after 5 or 15 mg folic acid per day. Before folio acid was given serum phenytoin was similar in patients deficient or not in folacin on similar anti. convulsant therapy treatment but values were higher in patients deficient in folacin than in those not so deficient. Serum phenobarbitone remained unchanged during folic acid treatment. In folacin-deficient patients given 15 mg folio acid per day serum phenytoin fell after 1 month, but there was no increase in frequency of fits. In patients given 5 mg folio acid per day serum phenytoin fell after 10 days or 1 month of treatment with folio acid and in one patient there was a great increase in frequency and severity of fits, thought to be due to reduction of serum phenytoin to below the therapeutic range, 10 to 20 micro g per ml. S.