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Time to consider a skeletal muscle relaxant?

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When you see conditions such as low back pain or neck pain, do you check for muscle spasm in and around the area of pain?
 
It may help to explain to patients that their skeletal muscles respond to cues of distress or potential damage by contracting in an attempt to protect joints and nerves.
 
The exact causes of these cues can vary, from poor posture to repetitive movements to acute injury. When the muscles spasm like this it can contribute to pain.
 
Be prepared to tackle muscle spasm with a skeletal muscle relaxant
Skeletal muscle spasm associated with back pain, neck pain and tension headache can be treated with a skeletal muscle relaxant (SMR). But which SMR?
 
After all, SMRs are not all the same. In fact, there are a variety of compounds with different mechanisms of action and tolerability profiles to consider.
 
Broadly, there are two categories of SMR – antispasticity agents and antispasmodic agents, with one type of medication that works as both. The antispasticity agents are indicated for spastic conditions like those seen in multiple sclerosis and spinal lesions.
 
Benzodiazepines act as both antispasticity and antispasmodic agents by increasing GABA-mediated presynaptic inhibition at spinal and supra-spinal sites.
 
Adverse events range from drowsiness, fatigue and poor muscle control to the risks of dependence and tolerance, benzodiazepines also have little to no evidence supporting their use in conditions like low back pain.
 
Only one randomised controlled trial has been conducted on benzodiazepines in acute low back pain over the past four decades, showing no additional benefit when added to non-steroidal anti-inflammatory drugs (NSAIDs) alone.
 
Orphenadrine is a non-benzodiazepine, non-opioid antispasmodic agent indicated for back pain, neck pain and tension headache.
 
While orphenadrine’s exact mechanism of action has not been determined, the following effects have been established:

• Antihistamine effects – orphenadrine is an H1 histamine receptor antagonist (H1 receptors mediate neurotransmission in the central nervous system [CNS])
• Anticholinergic effects – orphenadrine blocks muscarinic acetylcholine receptors in the CNS, as well as N-methyl-D-aspartate (NMDA) receptors, which may interfere with the transmission of nerve impulses from the spinal cord to skeletal muscles, helping them to relax
• Serotonergic effects – orphenadrine appears to affect the descending serotonergic projections in the spinal cord, potentially giving an antinociceptive effect

Orphenadrine, both alone or in combination with paracetamol, has been shown to be effective on painful muscle spasm, in comparison to placebo.
 
Adverse events associated with orphenadrine are mainly related to its anticholinergic activity and are reduced by dose reduction. They include dryness of the mouth, tachycardia, palpitations, urinary hesitancy or retention, blurred vision, dilation of the pupils, increased ocular tension, weakness, nausea, headache, dizziness, constipation and drowsiness.
 
Discover ways to utilise orphenadrine in practice and review case studies online.
 
This advertorial was commissioned by iNova Pharmaceuticals and independently reviewed by newsGP.
 
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