Is Methocarbamol Stronger Than Diazepam?

Is Methocarbamol Stronger Than Diazepam?

These two medications are indicated to treat and manage painful muscle spasms. However, they do so by way of different mechanisms, and belong to different drug classes.

Methocarbamol is a type of medication classified as a carbamate derivative – simply referring to the arrangement of compounds that constitute the medication – and is centrally acting. On the other hand, Diazepam is a benzodiazepine – a type of medication that slows brain activity – which also acts centrally, but does so via enhancing the action of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). This leads to a sedative and muscle-relaxant effect.You can read about diazepam's time for peak effect here.

Mechanism of Action

Methocarbamol acts centrally, which means it produces its effect through its action on the brain and spinal cord, as opposed to directly acting on the muscles. Although its precise mechanism is not fully understood (more on that here), it is thought to create inhibition of polysynaptic reflexes – which are complex networks of reflex arcs that can trigger muscle contraction in the spinal cord - and emerging evidence suggests it may inhibit Acetylcholinesterase, which is an enzyme involved in transmitting nerve signals to muscles.

Whereas, Diazepam facilitates GABA’s inhibitory effects, thereby decreasing the overall excitability of the central nervous system.

Comparative Efficacy and Potency

Regarding the literature, there are few robust studies that compare Methocarbamol and Diazepam’s efficacy. However, Sharifi et (2023) compared the effectiveness of Methocarbamol and diazepam for low back pain and both were shown to be equally effective. Chou et al (2004), although highlighting differing metrics upon which they were assessing various muscle relaxants, did conclude that both methocarbamol and diazepam are effective are reducing muscle spasms. So as you can see, the choice according to the literature depends on many things.

Safety Profile and Considerations and how this shapes what medication is right for you?

Deciding which drug is ‘stronger’ will depend, like all medications, on your overall health status, your clinical goals and the dosage of the medication in question. Methocarbamol, while effective at relieving muscle tension tends to have fewer sedative properties. Still, it may not be as potent for severe muscle spasms, in my clinical experience. But Diazepam carries a higher risk of dependence and withdrawal. This is one of the reasons why Diazepam is a controlled medication in the United Kingdon due to its potential for abuse. Whereas, Methocarbamol at present is not classified as a controlled drug.

If you would like to consult with me about being prescribed a muscle relaxant, you can do so here.

References

1. Chou, R., Peterson, K., & Helfand, M. (2004). Comparative efficacy and safety of skeletal muscle relaxants for spasticity and musculoskeletal conditions: a systematic review. Journal of Pain and Symptom Management, 28(2), 140–175. https://doi.org/10.1016/j.jpainsymman.2004.05.002

2. Sharifi, M., Abdorazzaghnejad, A., Yazdchi, M., & Bahreini, M. (2023). Methocarbamol versus diazepam in acute low back pain in the emergency department: a randomised double-blind clinical trial. Emergency Medicine Journal, 40(7), 493–498. https://doi.org/10.1136/emermed-2021-211485

3. BNF is only available in the UK. (n.d.). NICE. https://bnf.nice.org.uk/drugs/methocarbamol/

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