Muscle Relaxant Drugs: 12 of the Most Used

Muscle relaxants are drugs used to treat spasms and spasticity. Read on and find out which are the most common ones, as well as their effects and contraindications.

There are two basic types of muscle relaxant drugs. Some are used to treat spasms (carisoprodol, chlorzoxazone, and cyclobenzaprine), and others are for spasticity (baclofen, dantrolene, diazepam).

These are sensitive drugs that require a prescription. The reason is that some of them can interact with other substances, as well as produce side effects.

In this article, we’ll learn what muscle relaxant drugs are, their purposes, precautions for use, and contraindications. It should be noted that the intention of this article is only informative.

What are muscle relaxant drugs and what are they used for?

As the name implies, these drugs are used in the treatment of certain muscle problems. Specifically, they’re recommended for spasms as well as spasticity.

Spasms or cramps refer to sudden, involuntary contractions of one or more muscles. These can be caused by accumulated tension and occur with pain.

In spasticity, on the other hand, the muscle feels stiff, making it difficult to flex a joint. It’s caused by lesions in the nerves involved in the movement. It can be a symptom of some conditions, such as multiple sclerosis, amyotrophic lateral sclerosis, and cerebral palsy.

Muscle relaxant drugs can help soothe or reduce pain and discomfort related to spasms and spasticity, even in clinical conditions such as irritable bowel syndrome. However, they don’t attack the root cause.

It should be noted that these drugs shouldn’t be interchanged, i.e., they cannot be administered in place of each other. Therefore, antispasmodics shouldn’t be used for spasms, although some antispasmodics (such as tizanidine), are also recommended in spasticity.

Commonly used antispasmodic muscle relaxant drugs

Antispasmodics act on the nervous system, producing a sedative effect, in the sense that they block or inhibit pain signals. It’s advisable not to use them for more than 2 to 3 weeks.

On the other hand, so far they haven’t proven to be more effective than non-steroidal anti-inflammatory drugs or acetaminophen, but they do have more side effects than these. Among the best known are the following.

1. Carisoprodol

Carisoprodol comes in 350-milligram (mg) tablets. It’s recommended for musculoskeletal disorders with pain caused by sprains, strains or other injuries. It can also be found in combination with aspirin or codeine.

2. Chlorzoxazone

Known under the brand names Parafon ® or Lorzone ®, chlorzoxazone is also used to relieve pain and contractions due to muscle tears or sprains. In treatment, it’s often used in conjunction with aspirin or analgesics such as acetaminophen.

3. Metaxalone

Commercially called Skelaxin ® or Metaxall ®. It’s administered orally and comes in 800 mg tablets. This muscle relaxant is effective, but relatively potent, so it should be taken in moderation.

4. Methocarbamol

The best-known trade name for this muscle relaxant is Robaxin®. It comes in 500 mg tablets. It’s considered ineffective for low back pain, as well as in cases of rheumatoid arthritis and cerebral palsy muscle problems.

The maximum dose in adults is 2 to 3 tablets 4 times daily (4 to 6 grams per day). But the dose should be adjusted for elderly people and patients with liver disease.

5. Orphenadrine

Norflex® is a muscle relaxant for oral administration. It has an anticholinergic effect and is therefore recommended for pain and to help with motor control in people with Parkinson’s disease.

6. Tizanidine

Tizanidine is an alpha-2 receptor agonist muscle relaxant that works in the spinal cord. It’s centrally acting and slows down the action of the brain and nervous system.

7. Cyclobenzaprine

Cyclobenzaprine is a tricyclic drug. It comes in various forms, usually 5 to 10 mg.

It’s administered 2 to 4 times a day, the maximum dose being 60 mg/day. It’s useful for pain, but not for spasticity or stiffness.

Commonly used antispastic muscle relaxants

The other group of muscle relaxants is made up of antispastics. These include the following.

8. Baclofen

Baclofen (Lioresal® ) is used for spasticity in multiple sclerosis. It’s supposed to work by blocking the nerve signals sent by the spine that trigger spasms.

9. Dantrolene

Known commercially as Dantrium®, dantrolene is also prescribed in cases of multiple sclerosis, as well as for muscle spasms caused by stroke, spinal cord injury and cerebral palsy. Unlike the former, it acts on skeletal muscle.

10. Diazepam

Diazepam (Valium ®) is a drug belonging to the benzodiazepine group. It’s used in depression and anxiety, and is also a muscle relaxant that helps to relieve spasms.

Other drugs prescribed as muscle relaxants

Apart from those already mentioned, some drugs may be recommended by health professionals to treat problems such as spasticity, without actually being muscle relaxants.

11. Benzodiazepines

Other benzodiazepines can help to relax muscles, due to their sedative effects. These include clonazepam and alprazolam.

12. Gabapentin

Gabapentin is an anticonvulsant. It also helps to relieve muscle spasticity, although its function is not fully understood.

Precautions and contraindications

Muscle relaxants interact with alcohol and other drugs. Therefore, concomitant use with opioid analgesics, psychotropics, and central nervous system depressants should be avoided.

Because of their sensitive use, a physician should be consulted in the following cases:

• Adults over 65 years old and under 18 years old
• Patients with mental disorders
• Liver disease and kidney failure

Side effects of muscle relaxants

Muscle relaxants can produce a variety of side effects. The most common are the following:

• Drowsiness and fatigue
• Dizziness or loss of balance
• Headaches
• Nervous agitation
• Difficulty concentrating or remembering things

Prolonged treatment with muscle relaxants should be avoided, as some can create dependence, as well as withdrawal syndrome.