What are the different types of muscle relaxant medications?

From the Guidelines

Muscle relaxant medications can be broadly categorized into centrally acting muscle relaxants, benzodiazepines, and direct-acting muscle relaxants, with each type having its own set of commonly prescribed medications and dosages. The main types of muscle relaxants include:

• Centrally acting muscle relaxants, such as cyclobenzaprine (Flexeril), carisoprodol (Soma), and methocarbamol (Robaxin), which are typically prescribed for short-term use due to potential side effects and risk of dependence 1.
• Benzodiazepines, such as diazepam (Valium), which can also relieve muscle spasms, but are associated with a greater risk for central nervous system adverse events, such as somnolence, fatigue, and lightheadedness 1.
• Direct-acting muscle relaxants, such as baclofen (Lioresal) and tizanidine (Zanaflex), which are commonly used for severe spasticity, and dantrolene (Dantrium), which works directly on muscles rather than through the central nervous system. Some key points to consider when prescribing muscle relaxants include:
• The potential for drowsiness and the need to avoid combining these medications with alcohol or other central nervous system depressants.
• The risk of dependence and the need for short-term use (2-3 weeks) to minimize this risk.
• The importance of monitoring for adverse events, such as somnolence, fatigue, and lightheadedness, particularly with benzodiazepines.
• The need to individualize treatment and adjust dosages based on patient response and tolerance. It is essential to weigh the benefits and risks of each medication and to consider the individual patient's needs and medical history when selecting a muscle relaxant 1.

From the FDA Drug Label

Diazepam is a useful adjunct for the relief of skeletal muscle spasm due to reflex spasm to local pathology Cyclobenzaprine HCl relieves skeletal muscle spasm of local origin without interfering with muscle function. There are two types of muscle relaxant medications mentioned:

• Benzodiazepines, such as diazepam, which can be used as an adjunct for the relief of skeletal muscle spasm due to reflex spasm to local pathology 2
• Tricyclic antidepressant-like muscle relaxants, such as cyclobenzaprine, which relieves skeletal muscle spasm of local origin without interfering with muscle function 3

From the Research

Types of Muscle Relaxant Medications

The following are different types of muscle relaxant medications:

• Centrally acting skeletal muscle relaxants, such as metaxalone, cyclobenzaprine, and carisoprodol 4
• Baclofen, tizanidine, and dantrolene, which are effective for spasticity, primarily in patients with multiple sclerosis 5
• Orphenadrine, which is used to treat musculoskeletal conditions, such as acute back or neck pain 5
• Methocarbamol and chlorzoxazone, which have limited or inconsistent data regarding their effectiveness in patients with musculoskeletal conditions 5
• Diazepam, which can be used to treat muscle spasm 6
• Quinine sulfate, which can be used to treat muscle cramps 6

Characteristics of Muscle Relaxant Medications

Some muscle relaxants have specific characteristics, such as:

• Sedation, which is a common side effect of cyclobenzaprine 7
• Anticholinergic side effects, which are associated with cyclobenzaprine 4
• Potential for physical and psychological dependence, which is a concern with carisoprodol 4
• Hepatotoxicity, which is a rare but serious side effect of dantrolene and chlorzoxazone 5

Efficacy of Muscle Relaxant Medications

The efficacy of muscle relaxant medications varies:

• Cyclobenzaprine has been consistently found to be effective in patients with musculoskeletal conditions 5, 7
• Metaxalone, carisoprodol, and orphenadrine have been found to be effective compared to placebo in patients with musculoskeletal conditions 5
• Baclofen, tizanidine, and dantrolene have been found to be effective in patients with spasticity 5