From the Guidelines
Robaxin (methocarbamol) is generally considered less sedating than Norflex (orphenadrine). Both medications are muscle relaxants used to treat muscle spasms and pain, but they differ in their sedative effects. Robaxin works primarily by depressing the central nervous system and inhibiting multisynaptic reflex arcs, while Norflex has anticholinergic properties that can cause more pronounced central nervous system effects.
Key Differences
- Norflex has anticholinergic properties that can cause more pronounced central nervous system effects, leading to increased sedation 1.
- Robaxin is less likely to cause sedation due to its mechanism of action, which primarily involves inhibiting multisynaptic reflex arcs.
- In clinical practice, patients typically report more drowsiness and sedation with Norflex compared to Robaxin.
Considerations for Use
- Both medications can cause some degree of sedation, so patients should be cautious about driving or operating machinery until they know how either medication affects them.
- If sedation is a concern, starting with a lower dose at bedtime and gradually increasing as tolerated can help minimize this side effect.
- Patients with liver or kidney impairment may experience increased sedation with either medication and may require dose adjustments.
Clinical Evidence
- A higher-quality Cochrane review found skeletal muscle relaxants, including Robaxin and Norflex, to be moderately superior to placebo for short-term pain relief, but did not specifically compare the sedative effects of the two medications 1.
- The review noted that there was insufficient evidence to conclude that any specific muscle relaxant is superior to others for benefits or harms, including sedation 1.
From the FDA Drug Label
Methocarbamol is a central nervous system (CNS) depressant with sedative and musculoskeletal relaxant properties. The mode of action of methocarbamol has not been clearly identified, but may be related to its sedative properties.
The available information from the drug labels of Methocarbamol (Robaxin) indicates that it has sedative properties. However, there is no direct information in the provided drug labels about Norflex (Orphenadrine) to compare its sedating effects with Robaxin (Methocarbamol).
- Key point: The sedating effects of Methocarbamol are acknowledged, but a comparison with Norflex cannot be made based on the given information. 2 2
From the Research
Sedating Effects of Norflex (Orphenadrine) and Robaxin (Methocarbamol)
- The sedating effects of Norflex (Orphenadrine) and Robaxin (Methocarbamol) are compared in several studies 3, 4, 5, 6.
- According to a systematic review, methocarbamol and metaxalone are less sedating than other skeletal muscle relaxants such as tizanidine and cyclobenzaprine 4.
- Another study found that orphenadrine has sedative properties, but the evidence is limited 3.
- A review of commonly used muscle relaxant therapies for acute low back pain found that carisoprodol, cyclobenzaprine hydrochloride, and metaxalone are effective, but the potential for abuse with carisoprodol is a concern 6.
- The choice of skeletal muscle relaxant should be based on side-effect profile, patient preference, abuse potential, and possible drug interactions 4.
Comparison of Sedating Effects
- There is fair evidence that cyclobenzaprine, carisoprodol, orphenadrine, and tizanidine are effective compared to placebo in patients with musculoskeletal conditions, but the sedating effects of these drugs vary 3.
- Methocarbamol and metaxalone are less sedating than cyclobenzaprine and tizanidine, but the evidence is limited 4.
- Orphenadrine has sedative properties, but the evidence is limited 3.
- The sedating effects of methocarbamol are less pronounced compared to other skeletal muscle relaxants such as cyclobenzaprine and tizanidine 4, 6.