Dosing and uses of Magnesium (antidote)
Adult dosage forms and strengths
IV infusion, premixed in D5W
- 10mg/mL
- 20mg/mL
IV infusion, premixed in water
- 40mg/mL
- 80mg/mL
injection for dilution
- 500mg/mL
Digitalis Toxicity
1-2 g IVP over 5 minutes, then 1 g/hr drip (if Digibind not available)
Monitor levels q2hr; therapeutic goal is 4.5 mEq/L
Other Indications & Uses
Hydrofluoric acid burns
Pediatric dosage forms and strengths
injection for dilution
- 500mg/mL
Hypomagnesemia or Torsades de Pointes
Indicated for the treatment of documented hypomagnesemia or for torsades de pointes (polymorphic VT associated with long QT interval)
There is insufficient evidence to recommend for or against the routine administration of magnesium during cardiac arrest
25-50 mg/kg IV/IO over 10-20 minutes (may infuse faster in torsades de pointes); not to exceed 2 g/dose
Kleinman ME, et al. Circ 2010 Nov;122(18):S876-S908
Magnesium (antidote) adverse (side) effects
Frequency not defined
Flushing
Hypotension
Hypothermia
CNS depression
Motor & respiratory paralysis
Abnormal ECg
Diarrhea
Heart block
Prolonged bleeding time
Warnings
Contraindications
Hypersensitivity
Heart block
Myocardial disease
Cautions
Caution in myasthenia gravis or other neuromuscular disease
Caution in renal impairment
Serum levels poorly correlate to body stores
Pregnancy and lactation
Pregnancy category: A
Lactation: safe
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Magnesium (antidote)
Mechanism of action
Co-factor in enzymatic processes
Slows the rate of S-A node impulse formation in the myocardium and prolongs conduction time
Stabilizes excitable membranes by promoting the movement of sodium, calcium, and potassium in and out of the celL
Pharmacokinetics
Distribution: Bone (50-60%); extracellular fluid (1-2%)
Protain binding: 30%
Excretion: Urine
