What is the role of carbamazepine in the treatment of trigeminal neuralgia (TN)?

Updated: Jul 11, 2019
  • Author: Manish K Singh, MD; Chief Editor: Robert A Egan, MD  more...
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Answer

Carbamazepine acts by inhibiting the neuronal sodium channel activity, thereby reducing the excitability of neurons. A 100-mg tablet may produce significant and complete relief within 2 hours, and for this reason, it is a suitable agent for initial trial, although the effective dose ranges from 600-1200 mg/d, with serum concentrations between 40-100 mcg/mL. Indeed, serum levels of carbamazepine (but not necessarily phenytoin) in ranges appropriate for epilepsy may be necessary, at least to control initial symptoms, although a much smaller maintenance dosage may be adequate thereafter.

So predictable and powerful is the relief that if the patient does not respond at least partially to carbamazepine, reconsider the diagnosis of idiopathic trigeminal neuralgia.

Once a patient experiences breakthrough pain on a single agent, a second and even third additional medication may be required to restore relief. If this dosage does not relieve the discomfort adequately, administer a higher dose.

Many adverse central nervous system (CNS) effects (eg, vertigo, sedation, ataxia, diplopia) are associated with carbamazepine, which may make it difficult to use in elderly patients. The dose may be tapered once pain is controlled, since remission may occur.


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