I. Indications

  1. Preterm Labor for tocolysis or prevention of cerebral palsy for preterm birth < 30wks (click link for details)
  2. Preeclampsia
  3. Torsades des Pointes

II. Contraindications

  1. Renal failure
  2. Hypocalcemia
  3. Myasthenia gravis
  4. Don't combine with calcium-channel blockers

III. Dosing guidelines:

  1. Check serum Cr first!! (Mg is excreted by kidneys)  If high, lower infusion rate
  2. First give NS 500ml over 30min then bolus 4-5g over 20min then 2-3.5g/h, then 2-3g/h titrated to DTR's & serum Mg levels
    1. One protocol used for tocolysis calls for, after bolus is given, increasing rate by 0.5/h Q15-30min until sig. side effects or ctx stop; then decrease by 0.6g/h Q1h to min of 2g/h as long as ctx absent
  3. Target levels = 4-8mg/dL
  4. Consider checking levels 2h post-loading then Q4-6h
  5. Evaluate Qhour:
  1. DTR's (should be present)--earliest sign of toxicity
  2. Respirations (should be >12/minute)
  3. Urine output (should be >30cc/h)

IV. Adverse reactions:

  1. Nausea
  2. Flushing
  3. Dizziness
  4. Dry mouth
  5. Headache
  6. Somnolence
  7. Blurred vision
  8. Weakness and hyporeflexia (lose DTR's at 10mg/dL)
  9. Respiratory depression (respiratory arrest usually occurs at 12mg/dL)
  10. Oliguria
  11. Pulmonary edema

V. Antidote: CaGluconate 1gIV slow push over 3min; have @ bedside