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08. Lamotrigine Interactions: Practical Recommendations on Divalproex, Carbamazepine and Oral Contraceptives Use

Published on February 1, 2018 Expired on April 1, 2021

James Phelps, M.D.

Research Editor - Psychopharmacology Institute

Key Points

  • Divalproex
    • If adding divalproex to lamotrigine: reduce lamotrigine dose by 50%
    • If adding lamotrigine to divalproex: start with half a pill (12.5 mg) or use the pediatric dose of 5 mg and increase by one pill every 4 days
  • Carbamazepine
    • If carbamazepine is stopped and the patient is already on lamotrigine, be prepared for increased lamotrigine blood levels and manage accordingly
    • If carbamazepine is added and the patient develops depressive symptoms, lamotrigine dose can be increased
  • Oral contraceptives
    •  Lamotrigine’s interaction with oral contraceptives is clinically insignificant, except for the misconceptions among pharmacists

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Transcript

So let’s look at clinically relevant drug interactions. There are two drug interactions with lamotrigine that must be managed carefully, when you add it to divalproex and when it is used with carbamazepine. Many clinicians understand these issues but I will review them here in a moment. There is one other interaction that doesn’t require management but it gets inaccurate press coverage, so I will review that as well and that is oral contraceptives.

References

  1. Kanner AM. When thinking of lamotrigine and valproic acid, think “pharmacokinetically”! Epilepsy Curr . 2004 Sep–Oct;4(5):206–7.
  2. Perucca E. Clinically relevant drug interactions with antiepileptic drugs. Br J Clin Pharmacol . 2006 Mar;61(3):246–55.
  3. Christensen J, Petrenaite V, Atterman J, et al. Oral contraceptives induce lamotrigine metabolism: evidence from a double-blind, placebo-controlled trial. Epilepsia . 2007 Mar;48(3):484–9.
  4. Wegner I, Edelbroek PM, Bulk S, Lindhout D. Lamotrigine kinetics within the menstrual cycle, after menopause, and with oral contraceptives. Neurology . 2009 Oct 27;73(17):1388–93
  5. Lamictal Interactions
  6. 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.

Learning Objectives:

After completing this activity, the learner will be able to:

  1. Describe the concept of the bipolar spectrum as a dimensional approach to mood disorders
  2. Review the efficacy, safety and practical uses of lamotrigine

Original Release Date: 02/01/2018

Expiration Date: 04/01/2022

Relevant Financial Disclosures: 

The following planners, faculty, and reviewers have the following relevant financial relationships with commercial interests to disclose:

Dr. Phelps has disclosed the following relationships:

  • McGraw-Hill, W.W. Norton & Company: Books on bipolar disorders
  • McGraw-Hill: Book on Bipolar II / Bipolar NOS
  • W.W.Norton & Co.: Books on a spectrum approach to mood disorders

All of the relevant financial relationships listed for these individuals have been mitigated.

Contact Information: For questions regarding the content or access to this activity, contact us at support@psychopharmacologyinstitute.com

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