What is the recommended dose of cyclobenzaprine (muscle relaxant) for radicular pain?

Cyclobenzaprine Dosing for Radicular Pain

Cyclobenzaprine is not recommended for radicular pain, as the available evidence shows it is ineffective for this indication and may cause harm. 1

Evidence Against Use in Radicular Pain

The most relevant high-quality evidence comes from a 2017 systematic review for the American College of Physicians, which found:

• A good-quality trial (n=60) demonstrated that diazepam 5 mg three times daily (a benzodiazepine muscle relaxant similar in class to cyclobenzaprine) showed no difference in function compared to placebo for acute radiculopathy (median improvement on Roland Disability Questionnaire at 1 week: 3.0 vs 5.0 points, P=0.67) 1

• More concerning, diazepam was significantly less likely to provide pain relief of 50% or greater at 1 week compared to placebo (41% vs 79%; RR 0.5, CI 0.3-0.8), suggesting potential harm 1

• For skeletal muscle relaxants in general, evidence was insufficient from small placebo-controlled trials with inconsistent results to determine effects on chronic low back pain, and no trials evaluated acute radicular pain specifically 1

Why Cyclobenzaprine Is Not Appropriate

Radicular pain is neuropathic in origin, caused by nerve root compression or inflammation, not muscle spasm. 1 Cyclobenzaprine's mechanism targets muscle spasm through central nervous system depression, which does not address the underlying pathophysiology of radiculopathy 2.

Recommended Alternatives for Radicular Pain

For neuropathic radicular pain, evidence-based first-line options include:

• Gabapentin: Start 100-300 mg at bedtime, increase to 900-3600 mg daily in divided doses 2-3 times daily 1

  • Dose increments of 50-100% every few days with slower titration for elderly or medically frail patients 1
  • Requires dose adjustment for renal insufficiency 1

• Pregabalin: Start 50 mg three times daily, increase to 100 mg three times daily, maximum 600 mg daily in divided doses 1

  • More efficient absorption than gabapentin with linear pharmacokinetics 1
  • Also requires renal dose adjustment 1

• Tricyclic antidepressants (nortriptyline or desipramine): Start 10-25 mg nightly, increase to 50-150 mg nightly 1

  • Secondary amines better tolerated than tertiary amines 1
  • Effective for neuropathic component of pain 1

Critical Pitfall to Avoid

Do not confuse mechanical low back pain with muscle spasm (where cyclobenzaprine may have limited short-term benefit) with radicular pain from nerve root pathology (where it is ineffective). 1 The distinction is critical: radicular pain radiates down the leg following a dermatomal pattern, often with neurological signs, whereas mechanical pain with spasm is localized to the back without nerve involvement 1.

If Cyclobenzaprine Were to Be Used (Not Recommended for Radicular Pain)

The FDA-approved dosing for muscle spasm (not radicular pain) is 5 mg three times daily, with possible increase to 10 mg three times daily based on response, for no longer than 2-3 weeks. 2 However, this dosing is irrelevant for radicular pain given the lack of efficacy and potential for harm in this condition 1.