Is carbamazepine (CBZ) used to treat multiple sclerosis (MS)?

Carbamazepine is Not Used to Treat Multiple Sclerosis but May Be Used for Specific MS-Related Pain Syndromes

Carbamazepine is not indicated for the treatment of multiple sclerosis itself, but it is a first-line treatment for certain pain syndromes that can occur in MS patients, particularly trigeminal neuralgia and painful paroxysmal symptoms.

Role of Carbamazepine in MS-Related Pain

Trigeminal Neuralgia in MS

• Carbamazepine is the first-line treatment for trigeminal neuralgia in MS patients 1, 2
• Affects less than 5% of MS patients but can cause extreme pain 1
• Dosing typically starts at 200 mg at night and gradually increases by 200 mg every 7 days to a final dose of 400-1200 mg divided in 2-3 doses per day 3

Painful Paroxysmal Symptoms

• Carbamazepine is first-choice treatment for painful tonic spasms and other paroxysmal symptoms in MS 2
• These symptoms affect approximately 11% of MS patients 1
• Low-dose therapy (50-200 mg/day) is often effective 3

Adverse Effects and Cautions

MS-Specific Concerns

• Carbamazepine has a significantly higher incidence of adverse effects in MS patients compared to other anticonvulsants like gabapentin or lamotrigine 4
• 12 out of 36 MS patients in one study experienced adverse effects that mimicked MS relapse, leading to diagnostic confusion 4
• High rate of treatment discontinuation even at low dosages 4

General Adverse Effects

• Common side effects include drowsiness, headache, and dizziness 3
• Risk of Stevens-Johnson syndrome/toxic epidermal necrolysis, particularly in patients with HLA-B*15:02 genotype 3
• HLA-B*15:02 screening recommended before initiating treatment in high-risk populations 3

Alternative Treatments for MS-Related Pain

For Trigeminal Neuralgia and Paroxysmal Symptoms

• Oxcarbazepine (600-1200 mg/day) has shown efficacy in treating painful paroxysmal symptoms in MS with potentially better tolerability 5
• Lamotrigine, gabapentin, and oxcarbazepine are second-line options if carbamazepine is not tolerated 2, 6
• Combination therapy with pregabalin plus lamotrigine may be effective for refractory trigeminal neuralgia 6

For Other MS-Related Pain

• Painful "burning" dysesthesias (most common chronic pain syndrome in MS) are treated with tricyclic antidepressants or anticonvulsants 2
• Cannabinoids have been studied in randomized controlled trials for central neuropathic pain in MS 1
• Gabapentin has demonstrated efficacy for painful spasms in MS 1

Clinical Decision Algorithm

1. Identify the specific type of pain syndrome in the MS patient:

   • Trigeminal neuralgia → Consider carbamazepine first-line
   • Painful tonic spasms → Consider carbamazepine first-line
   • Burning dysesthesias → Consider tricyclic antidepressants first-line
   • Spasticity-related pain → Consider baclofen or tizanidine first-line

2. If carbamazepine is indicated:

   • Screen for HLA-B*15:02 in high-risk populations
   • Start at low dose (50-200 mg/day)
   • Monitor closely for adverse effects that may mimic MS relapse
   • Consider oxcarbazepine, lamotrigine or gabapentin if carbamazepine is not tolerated

3. For patients who fail first-line therapy:

   • Consider combination therapy (e.g., pregabalin plus lamotrigine)
   • Consult with pain specialist for refractory cases

Remember that carbamazepine treats specific MS-related symptoms but does not modify the disease course of MS itself.