How the interaction occurs:
Estrogen increases how quickly your body removes lamotrigine. Lamotrigine may increase how quickly your body removes contraceptive medicine.
What might happen:
The amount of lamotrigine and estrogen in your blood may be lowered. You may have more seizures if you are taking lamotrigine for a seizure disorder. If you are taking an oral contraceptive, it may not work as well to prevent pregnancy.
What you should do about this interaction:
Make sure your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together. Let your doctor know right away if you notice any changes in your seizure frequency. Inform your doctor if you have any changes in your menstrual cycle, such as break-through bleeding. This may be a sign that your estrogen or estrogen-containing contraceptive may not be working.If you are taking carbamazepine, phenytoin, phenobarbital, primidone, ritonavir, or rifampin, then your doctor will probably not need to adjust your lamotrigine dose.If you are not taking one of these medicines, then your doctor may need to adjust the dose of your lamotrigine if you start or stop taking your estrogen or estrogen-containing contraceptive. Make sure that the doctor prescribing your lamotrigine knows if you start or stop taking estrogens or an estrogen-containing contraceptive. If you start an estrogen containing medicine your lamotrigine dose may need to be increased to maintain effectiveness. When you stop an estrogen containing medicine your lamotrigine dose may need be decreased to lower the risk for lamotrigine side effects.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Lamictal (lamotrigine) US prscribing information. GlaxoSmithKline December, 2014.
2.Dear Healthcare Professional, Subject: Important new safety information concerning the antiepileptic, LAMICTAL (lamotrigine). GlaxoSmithKline Canada September, 2004.
3.Sabers A, Ohman I, Christensen J, Tomson T. Oral contraceptives reduce lamotrigine plasma levels. Neurology 2003 Aug 26;61(4):570-1.
4.Sabers A, Buchholt JM, Uldall P, Hansen EL. Lamotrigine plasma levels reduced by oral contraceptives. Epilepsy Res 2001 Nov;47(1-2):151-4.
5.Reimers A, Helde G, Brodtkorb E. Ethinyl estradiol, not progestogens, reduces lamotrigine serum concentrations. Epilepsia 2005 Sep;46(9):1414-7.
6.Christensen J, Petrenaite V, Atterman J, Sidenius P, Ohman I, Tomson T, Sabers A. Oral contraceptives induce lamotrigine metabolism: evidence from a double-blind, placebo-controlled trial. Epilepsia 2007 Mar;48(3):484-9.
7.Contin M, Albani F, Ambrosetto G, Avoni P, Bisulli F, Riva R, Tinuper P, Baruzzi A. Variation in lamotrigine plasma concentrations with hormonal contraceptive monthly cycles in patients with epilepsy. Epilepsia 2006 Sep;47(9):1573-5.
8.Sidhu J, Job S, Singh S, Philipson R. The pharmacokinetic and pharmacodynamic consequences of the co-administration of lamotrigine and a combined oral contraceptive in healthy female subjects. Br J Clin Pharmacol 2006 Feb;61(2):191-9.