Carbamazepine Extended-Release Capsules (Carbatrol) and Foltanx

In the database of official manuals used in the service creation an interaction registered by statistical results of studies was found, which can either lead to negative consequences for the patient health or strengthen a mutual positive effect. A doctor should be consulted to address the issue of joint drug administration.

Consumer information for this interaction is not currently available.MONITOR: Anticonvulsants including, but not limited to, carbamazepine, lamotrigine, phenobarbital, phenytoin, primidone, and valproic acid have been shown to impair folate absorption and increase the metabolism of circulating folate. The precise mechanism of interaction has not been established. MONITOR: Coadministration with folate therapy may reduce the anticonvulsant effects of phenytoin, phenobarbital, primidone, and succinimides. The exact mechanism of interaction is unknown. Available data pertain primarily to phenytoin. Some investigators suggest that folic acid may serve as a cofactor in the metabolism of phenytoin, thus clearance is increased in the presence of folic acid. In one study, administration of folic acid for 14 days reduced the serum levels of phenytoin in normal subjects without significantly altering the bound fraction. Urinary excretion of phenytoin and its metabolite, meta-hydroxydiphenylhydantoin, was increased. In another study, three of four folate-deficient male patients receiving phenytoin monotherapy for epilepsy demonstrated a 7.5% to 47.6% decrease in total phenytoin plasma concentration following the addition of folic acid 1 mg/day for 180 or 300 days. Ratios of urinary metabolites to parent drug increased in these patients, suggesting an increase in phenytoin oxidative metabolism. The interaction is further supported by case reports describing subtherapeutic phenytoin levels and/or breakthrough seizures following the addition of folate therapy, including one case involving folinic acid (leucovorin). Limited data are available for phenobarbital and primidone. In one study, the addition of folic acid 15 mg/day increased the frequency and severity of seizures in 13 of 26 folate-deficient epileptic patients receiving two or more anticonvulsant drugs, including phenytoin, phenobarbital, and primidone. Nine of them required discontinuation of folic acid therapy. No data are available for other hydantoins. MANAGEMENT: Caution is advised when folate therapy is coadministered with anticonvulsants. Close monitoring for clinical and laboratory evidence of diminished therapeutic response to both treatments is recommended. Patients should be advised to notify their physician if they experience loss of seizure control. References Furlanut M, Benetello P, Avogaro A, Dainese R "Effects of folic acid on phenytoin kinetics in healthy subjects." Clin Pharmacol Ther 24 (1978): 294-7 Berg MJ, Fincham RW, Ebert BE, Schottelius DD "Phenytoin pharmacokinetics: before and after folic acid administration." Epilepsia 33 (1992): 712-20 Canadian Pharmacists Association "e-CPS. Available from: URL: http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink." Ch'ien LT, Krumdieck CL, Scott CW Jr, Butterworth CE Jr "Harmful effect of megadoses of vitamins: electroencephalogram abnormalities and seizures induced by intravenous folate in drug- treated epileptics." Am J Clin Nutr 28 (1975): 51-8 "Product Information. L-Methylfolate Calcium (l-methylfolate)." Virtus Pharmaceuticals LLC, Tampa, FL. Cerner Multum, Inc. "Australian Product Information." O 0 Yuen GJ "Interaction of phenytoin and folic acid: an alternative explanation." Clin Pharm 3 (1984): 116,119 "Product Information. Levoleucovorin (levoleucovorin)." Spectrum Chemical, Gardena, CA. Katz M "Potential danger of self-medication with folic acid." N Engl J Med 289 (1973): 1095 Berg MJ, Fischer LJ, Rivey MP, Vern BA, Lantz RK, Schottelius DD "Phenytoin and folic acid interaction: a preliminary report." Ther Drug Monit 5 (1983): 389-94 Lewis DP, Van Dyke DC, Willhite LA, Stumbo PJ, Berg MJ "Phenytoin-folic acid interaction." Ann Pharmacother 29 (1995): 726-35 Carl GF, Smith ML "Phenytoin-folate interactions: differing effects of the sodium salt and the free acid of phenytoin." Epilepsia 33 (1992): 372-5 Robenberg IH "Drugs and folic acid absorption." Gastroenterology 63 (1972): 353-7 Seligmann H, Potasman I, Weller B, Schwartz M, Prokocimer M "Phenytoin-folic acid interaction: A lesson to be learned." Clin Neuropharmacol 22 (1999): 268-72 "Product Information. Wellcovorin (leucovorin)." Glaxo Wellcome, Research Triangle Park, NC. Berg MJ, Rivey MP, Vern BA, Fischer LJ, Schottelius DD "Phenytoin and folic acid: individualized drug-drug interaction." Ther Drug Monit 5 (1983): 395-9 Veldhorst-Janssen NM, Boersma HH, de Krom MC, van Rijswijk RE "Oral tegafur/folinic acid chemotherapy decreases phenytoin efficacy." Br J Cancer 90 (2004): 745 Berg MJ, Stumbo PJ, Chenard CA, Fincham RW, Schneider PJ, Schottelius D "Folic acid improves phenytoin pharmacokinetics." J Am Diet Assoc 95 (1995): 352-6 Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0 MacCosbe PE, Toomey K "Interaction of phenytoin and folic acid." Clin Pharm 2 (1983): 362-9 Steinweg DL, Bentley ML "Seizures following reduction in phenytoin level after orally administered folic acid." Neurology 64 (2005): 1982 Agencia Española de Medicamentos y Productos Sanitarios Healthcare "Centro de información online de medicamentos de la AEMPS - CIMA. Available from: URL: https://cima.aemps.es/cima/publico/home.html." ([2018]): View all 22 references

MONITOR: Anticonvulsants including, but not limited to, carbamazepine, lamotrigine, phenobarbital, phenytoin, primidone, and valproic acid have been shown to impair folate absorption and increase the metabolism of circulating folate. The precise mechanism of interaction has not been established.

MONITOR: Coadministration with folate therapy may reduce the anticonvulsant effects of phenytoin, phenobarbital, primidone, and succinimides. The exact mechanism of interaction is unknown. Available data pertain primarily to phenytoin. Some investigators suggest that folic acid may serve as a cofactor in the metabolism of phenytoin, thus clearance is increased in the presence of folic acid. In one study, administration of folic acid for 14 days reduced the serum levels of phenytoin in normal subjects without significantly altering the bound fraction. Urinary excretion of phenytoin and its metabolite, meta-hydroxydiphenylhydantoin, was increased. In another study, three of four folate-deficient male patients receiving phenytoin monotherapy for epilepsy demonstrated a 7.5% to 47.6% decrease in total phenytoin plasma concentration following the addition of folic acid 1 mg/day for 180 or 300 days. Ratios of urinary metabolites to parent drug increased in these patients, suggesting an increase in phenytoin oxidative metabolism. The interaction is further supported by case reports describing subtherapeutic phenytoin levels and/or breakthrough seizures following the addition of folate therapy, including one case involving folinic acid (leucovorin). Limited data are available for phenobarbital and primidone. In one study, the addition of folic acid 15 mg/day increased the frequency and severity of seizures in 13 of 26 folate-deficient epileptic patients receiving two or more anticonvulsant drugs, including phenytoin, phenobarbital, and primidone. Nine of them required discontinuation of folic acid therapy. No data are available for other hydantoins.

MANAGEMENT: Caution is advised when folate therapy is coadministered with anticonvulsants. Close monitoring for clinical and laboratory evidence of diminished therapeutic response to both treatments is recommended. Patients should be advised to notify their physician if they experience loss of seizure control.

Carbamazepine Extended-Release Capsules (Carbatrol)

Generic Name: carbamazepine

Brand name: Carbatrol, Epitol, Equetro, Tegretol, Tegretol XR, Tegretol, Tegretol XR

Synonyms: Carbamazepine, CarBAMazepine

What is Carbamazepine Extended-Release Capsules (Carbatrol)?

Foltanx

Generic Name: l-methylfolate

Brand name: Deplin, L-Methylfolate Formula, XaQuil XR, L-Methylfolate Formula 75

Synonyms: L-methylfolate, Methylfolate

What is Foltanx?