Magnesium - Acetaminophen, Methocarbamol Interaction
Herbal: Magnesium
Also Known As: Chelated Magnesium, Dimagnesium Malate, Epsom Salts, Magnesia, Magnesium Aspartate, Magnesium Carbonate, Magnesium Chelate, Magnésium Chelaté, Magnesium Chloride, Magnesium Citrate, Magnesium Gluconate, Magnesium Glycerophosphate, Magnesium Glycinate
Drug: Acetaminophen, Methocarbamol
Brand names:
Robaxacet
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jul 22, 2023
Interaction Details
Acetaminophen, Methocarbamol is classified as belonging to the following category: Skeletal Muscle Relaxants
Parenteral magnesium alters the pharmacokinetics of skeletal muscle relaxants, increasing their effects and accelerating the onset of effect.
Parenteral magnesium shortens the time to onset of skeletal muscle relaxants by about 1 minute and prolongs the duration of action by about 2 minutes. Magnesium potentiates the effects of skeletal muscle relaxants by decreasing calcium-mediated release of acetylcholine from presynaptic nerve terminals, reducing postsynaptic sensitivity to acetylcholine, and having a direct effect on the membrane potential of myocytes. Magnesium also has vasodilatory actions and increases cardiac output, allowing a greater amount of muscle relaxant to reach the motor end plate. A clinical study found that low-dose rocuronium (0.45 mg/kg), when given after administration of magnesium 30 mg/kg over 10 minutes, has an accelerated onset of effect, which matches the onset of effect seen with a full-dose rocuronium regimen (0.6 mg/kg). In another clinical study, onset times for rocuronium doses of 0.3, 0.6, and 1.2 mg/kg were 86, 76, and 50 seconds, respectively, when given alone, but were reduced to 66, 44, and 38 seconds, respectively, when the doses were given after a 15-minute infusion of magnesium sulfate 60 mg/kg.
Interaction Rating
Likelihood of Occurrence
ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
References
- Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
- Choi ES, Jeong WJ, Ahn SH, Oh AY, Jeon YT, Do SH. Magnesium sulfate accelerates the onset of low-dose rocuronium in patients undergoing laryngeal microsurgery. J Clin Anesth. 2017 Feb;36:102-106.
- Rodríguez-Rubio L, Solis Garcia Del Pozo J, Nava E, Jordán J. Interaction between magnesium sulfate and neuromuscular blockers during the perioperative period. A systematic review and meta-analysis. J Clin Anesth. 2016;34:524-34.
- Almeida CED, Carvalho LR, Andrade CVC, Nascimento PD Jr, Barros GAM, Modolo NSP. Effects of magnesium sulphate on the onset time of rocuronium at different doses: a randomized clinical trial. Braz J Anesthesiol. 2021;71(5):482-8.
Magnesium Overview
Magnesium is a mineral that is essential for the proper functioning of the body. It plays a role in many important physiological processes, including the contraction and relaxation of muscles, the transmission of nerve impulses, and the regulation of blood pressure. Magnesium is found in a variety of foods, including leafy green vegetables, nuts, and grains, and it is also available as a dietary supplement.
There are several different forms of magnesium that are available as supplements, all of which can be used to prevent deficiency. Additionally, magnesium is purported to have several different health benefits, such as improving sleep, reducing muscle cramps, reducing anxiety, and preventing or treating migraines.
Although magnesium is essential for health, magnesium-containing foods and supplements can interact with some prescription medications if used at the same time.
Magnesium - More Interactions
Magnesium interacts with 276 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
| Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
| Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
| Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
| Unknown | No interactions have been reported or no interaction data is currently available. |
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Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Drug descriptions are provided by MedlinePlus.
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Dr. Brian Staiger, PharmD
In addition to being a clinical pharmacist specializing in pharmacotherapy, Dr. Brian Staiger is a registered herbalist through the American Herbalist Guild. He has combined his passion for pharmacy practice with the study of medical ethnobotany to improve patient care. Feel free to reach out about any of your herbal or medication questions!
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