Lamotrigine

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Contents 1 Introduction 2 Indications 3 Contraindications 4 Dosage 5 Adverse-effects 6 Drug-interactions 7 More General Terms 8 Additional Terms 9 Internet Database 10 References

Introduction

• Tradename: Lamictal.

Indications

• adjunctive treatment of partial seizures in patients > 16 years of age
• adjunctive therapy in primary generalized seizures, generalized tonic-clonic seizures [5,7]
• efficacy in myoclonic seizures & absence seizures [3]

Contraindications

• concurrent administration of valproic acid*

• Caution:

• use cautiously in patients with significant renal or hepatic dysfunction
• do not discontinue use abruptly
  

• pregnancy category = c
• safety in lactation = -

Dosage

• start 50 mg PO QD for 14 days, then
• 50 mg BID for 14 days, then
• maintenance 150-250 mg BID.

• * (ref 4 makes recommendations for use in connection with valproic acid)
• * 4) with valproic acid: start 25 mg QOD for 2 weeks, then

• 25 mg QD for 2 weeks
• maintenance 50-75 mg BID
  

• Tabs: 25, 100, 150, 200 mg; Lamictal XR ( extended-release) for partial seizures
• Oral disintegrating tabs: Lamical ODT

Adverse-effects

• weight loss common in elderly [5]
• not common (1-10%)

• headache, ataxia, dizziness, diplopia, sedation, lethargy, nystagmus
• nausea
• hematuria
• skin rash, angioedema, Stevens-Johnson syndrome
• EKG conduction delays, QRS complex widening

• increased chance of cleft lip or cleft palate in babies of pregnant women taking Lamictal [8]
• aseptic meningitis [10]
  

• Toxicity:

• associated with serum lamotrigine > 15 mg/L
• admit to telemetry, monitor for QRS widening
• activated charcoal for altert patients with intact airway
• infusion of sodium bicarbonate 150 meq in 1 L D5W may be of benefit for patients with QRS duration > 100 msec
• monitor serum K+
  
• drug adverse effects of anticonvulsants

Drug-interactions

• phenytoin, carbamazepine, primidone & barbiturates shorten the 1/2life
• valproic acid prolongs the 1/2life & increases risk of life-threatening dermatitis ( contraindicated)
• lamotrigine decreases valproic acid level
• lamotrigine increases carbamazepine level

More General Terms

• anticonvulsant

Additional Terms

• lamotrigine in serum

Internet Database

PubChem: 3878
PubChem: 164342

References

1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
2. Harrison's Principles of Internal Medicine, 13th ed. Companion Handbook. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1995, pg 702
3. Medical Knowledge Self Assessment Program (MKSAP) 11, 15, American College of Physicians, Philadelphia 1998, 2009
4. Kaiser Permanente Northern California Regional Drug Formulary, 1998
5. Journal Watch 25(15):118-19, 2005 Rowan AJ, Ramsay RE, Collins JF, Pryor F, Boardman KD, Uthman BM, Spitz M, Frederick T, Towne A, Carter GS, Marks W, Felicetta J, Tomyanovich ML; VA Cooperative Study 428 Group. New onset geriatric epilepsy: a randomized study of gabapentin, lamotrigine, and carbamazepine. Neurology. 2005 Jun 14;64(11):1868-73. PMID: [1]
6. Department of Veterans Affairs, VA National Formulary
7. Biton V et al, Double-bind, placebo-controlled study of lamotrigine in primary generalized tonic-clonic seizures. Neurololgy 2005, 65:1737 PMID: [2]
8. The Washington Manual of Medical Therapeutics, 33rd edition Foster C et al (eds) Lippincott, Williams & Wilkins, Philadelphia, 2010, pg 951
9. FDA MedWatch [3]
   - Prescriber's Letter 13(11): 2006 Increased Risk of Oral Clefts with use of Lamotrigine (Lamictal) During Pregnancy Detail-Document#: [4] (subscription needed) [5]
10. Lamictal (lamotrigine): Label Change - Risk of Aseptic Meningitis [6]
11. Greiner-Sosanko E et al Drug monitoring: simultaneous analysis of lamotrigine, oxcarbazepine, 10-hydroxycarbazepine, and zonisamide by HPLC-UV and a rapid GC method using a nitrogen-phosphorus detector for levetiracetam J Chromatogr Sci. 2007 October; 45(9): 616-622 [7]

lamotrigine (Lamictal, Lamictal ODT, Lamictal XR)