Mechanism of Muscle Relaxant

What are Muscle Relaxants? 

A class of medications known as muscle relaxants work by relaxing the skeletal muscles, reducing muscle tone, and relieving muscle spasms. 

While the specific drug determines the exact mechanism of action, most muscle relaxants reduce muscle activity by either acting on the central nervous system or interfering with the transmission of nerve impulses at the neuromuscular junction.

How do different muscle relaxants work on the body?

Peripheral muscle relaxants, like dantrolene, function by obstructing the release of calcium ions from the sarcoplasmic reticulum found in skeletal muscle cells. Calcium ions play a crucial role in muscle contraction, and by preventing their release, dantrolene reduces the amount of calcium accessible for muscle contraction. This leads to muscle relaxation.

Central muscle relaxants, such as baclofen and tizanidine, affect the central nervous system to decrease muscle activity.

Baclofen is a GABA agonist that binds to GABA-B receptors present in the spinal cord. This leads to hyperpolarization of spinal motor neurons and consequently reduces muscle tone. 

Tizanidine also works on the spinal cord by obstructing the release of stimulatory neurotransmitters such as glutamate and substance P. This inhibition results in a reduction of muscle activity.

Benzodiazepines are another type of central muscle relaxant, such as diazepam, which improve the activity of GABA-A receptors in the brain and spinal cord. GABA-A receptors are a type of inhibitory neurotransmitter receptors that decrease the excitability of neurons. As a result, they lead to a reduction in muscle tone.

Side effects of muscle relaxant:

Muscle relaxants are associated with multiple side effects, such as drowsiness, dizziness, and impaired coordination. 

These drugs can also interact with other medications, and their use must be closely monitored by a healthcare professional. 

Typically, muscle relaxants are prescribed for short-term use to treat acute muscle spasms resulting from conditions like neck pain, back pain, and fibromyalgia. For chronic muscle spasms, alternative therapies, such as physical therapy or surgery, may be considered.