From the FDA Drug Label
DOSAGE AND ADMINISTRATION: ... The rate of IV injection should generally not exceed 150 mg/minute (1. 5 mL of a 10% concentration or its equivalent)... In the treatment of mild magnesium deficiency, the usual adult dose is 1 g, equivalent to 8. 12 mEq of magnesium (2 mL of the 50% solution) injected IM every six hours for four doses (equivalent to a total of 32.5 mEq of magnesium per 24 hours). A total daily (24 hr) dose of 30 to 40 g should not be exceeded.
The maximum dose of magnesium IV that can be given is 30 to 40 g per day, with a rate of injection not exceeding 150 mg/minute. For pain management, the dose is not explicitly stated, but it can be inferred that a dose of 1 to 2 g may be used, as seen in other indications such as counteracting muscle-stimulating effects of barium poisoning or controlling seizures. However, the exact dose for pain management is not directly stated in the label 1.
From the Research
Intravenous magnesium sulfate can be administered at doses of 1-2 grams diluted in 100 mL of normal saline and infused over 15-30 minutes for acute pain management, with potential benefits in reducing pain transmission and opioid requirements, as suggested by the most recent study 2. When considering the use of magnesium for pain management, it is essential to weigh the potential benefits against the risks, particularly in patients with renal impairment or those taking other medications that may interact with magnesium. The evidence from recent studies, such as the 2024 review 2, suggests that intravenous magnesium may be a promising option for certain types of chronic pain, including renal colic pain and pelvic pain related to endometriosis. Key considerations for the use of magnesium in pain management include:
- Dosing: 1-2 grams diluted in 100 mL of normal saline and infused over 15-30 minutes, with potential for continuous infusion at 0.5-1 gram per hour for up to 24 hours 2
- Monitoring: Renal function should be assessed before administration, and serum magnesium levels should be monitored during treatment to minimize the risk of adverse effects 2
- Potential benefits: Reduction in pain transmission, decrease in opioid requirements, and potential benefits in certain types of chronic pain, such as renal colic pain and pelvic pain related to endometriosis 2, 3
- Potential risks: Hypotension, flushing, nausea, muscle weakness, and serious complications like respiratory depression and cardiac arrhythmias, particularly at higher doses 2, 4