Magnesium Sulfate and Pre-Eclampsia

1. MAGNESIUM SULFATE
AND
PRE-ECLAMPSIA
Donna Graham
Lamar University
Advanced Pharmacology

2.  Pregnancy induced hypertension (HTN) = hypertension without accompanying symptoms involved in
preeclampsia or eclampsia.
 Pre-eclampsia = hypertension, proteinuria, and swelling caused by fluid leaking out of the body's capillaries,
building up and getting trapped in tissues around the leaking blood vessels
 Eclampsia = one or more seizure occurring as a result of preeclampsia.
(Lu & Nightingale, 2000).

3. Hypertension = systolic blood pressure(SBP) >140 millimeters of mercury (mmHg) & diastolic
pressure (DBP) > 90 mmHg OR an increase in SBP of 30mmHg and an increase in DBP of 15
on two readings.
Proteinuria = 2+ concentration or 24 hour urine result of greater than 0.3 grams.
MAY INCLUDE:
Low Platelet Count
Impaired Liver Function
Fluid in Lungs (Pulmonary Edema)
New onset visual changes or headaches (Lu & Nightingale, 2000).

4. Magnesium Sulfate is mineral and a drug.
A cation like calcium or potassium.
An anticonvulsant
A potent vasodilator
A laxative
A Tocolytic
(Virkud, 2015).

5. Reduce and prevent seizures ante, intra and/or postpartum. Anticonvulsant.
 Mechanism of Action - not clearly understood.
 Some believe - may act mainly at neuromuscular junction and less so at central nervous system and others
believe the exact opposite to be true.
 Another theory - proposes that seizures result from decreased blood flow to the brain, and endothelial
dysfunction from free radical injury. The decreased blood flow and injury leads to intense vasospasms and
increased pressure receptor sensitivity causing seizures. Magnesium Sulfate administration increases blood
flow to the brain by increasing endothelial vasodilator prostacyclin which decreases or eliminates seizure
activity entirely.
(Lu & Nightingale, 2000)

6.  Potent Vasodilator - especially within the brain. It is an antagonist of calcium, acting on any vascular
calcium channels, decreasing calcium and causing dilation. It is also thought to protect the brain by
limiting cerebral edema.
 Neuroprotector - not only does Mg have brain protector abilities on the maternal side, evidence has
shown neuroprotective action in the fetus even to the extent of protecting the preterm fetus against
cerebral palsy.
(Virkud, 2015).

7.  Administered Intravenously (IV) or Intramuscularly (IM). Rapid distribution phase, more rapid when
administered IV. Protein Bound. Calcium antagonist, decreases intracellular calcium. Not metabolized. Slow
elimination phase.
 IV route has a faster rate of absorption resulting in immediate action with its effect lasing for about 30 minutes.
Absorption occurs slowly when given IM and reaches a plateau in 1-2 hours. Plasma concentration slowly
declines back to control level over the next 6-8 hours. When IM repeated every four hours the rates of
absorption, distribution and excretion are about equal and plasma concentration remains fairly constant. IM
injections are very irritating. Combining IV and IM administration may be beneficial for predictability in plasma
concentration levels.
 Clinical effect and toxicity linked to plasma concentration.
(Lu & Nightingale, 2000)

8.  The serum plasma level for therapeutic versus toxic levels of magnesium plasma is narrow.
 NORMAL SERUM LEVELS OF MAGNESIUM = 1.6 – 2.1 mmol/L.
 THERAPEUTIC SERUM LEVEL = 2-4 mm/L.
 TOXICITY BEGINS @ 3.5-5 mmol/L.
 The milder, more common side effects include an increased feelings of warmth, flushing, lethargy, blurred
vision, headaches, nausea, hypothermia, fecal impaction and urinary retention.
 MILDER REACTIONS LINKED TO PLASMA LEVELS OF 3.8 - 5 mmol/L.
 FIRST SIGN OF MAGNESIUM TOXICITY = LOSS OF PATELLAR REFLEX
 RESPIRATORY ARREST LINKED TO PLASMA LEVELS OF 5 – 6.5 mmol/L.
 CARDIAC ARRESST LINKED TO PLASMA LEVELS EXCEEDING 12.5 mmol/L.
(Lu & Nightingale, 2000) (Virkud,2015)

9.  MgSO4 + Calcium antagonist or Anesthetic Agent = Use with Caution and consider reducing the dosage.
 MgSO4 may potentiate the action of neuromuscular blocking agents whether they are polarizing or non-
polarizing and a dose reduction may be warranted.
 MgSO4 + Calcium channel blockers = Use with caution or not at all.
 When Magnesium is used with a calcium channel blocker and the two medications will have increased power to
perform their intended action.
 MGSO4 + Epidural anesthesia - both cause vasodilation but when given together they have only been shown to
minimally reduce BP beyond using one agent at a time (Lu & Nightingale, 2000). Using them concurrently have
not shown evidence of decreased oxygen or blood flow to the fetus or uterus
(Lu & Nightingale, 2000) (Virkud,2015)

10.  MgSO4 + Nifedipine = AVOID.
 Magnesium Sulfate are both calcium antagonists and so they have an additive affect when administered
together, decreasing BP further than when used alone. Using these drugs concurrently may result in harm or
death to fetus due to severe hypotension.
 MgSO4 +Renal Impairment = AVOID.
 Patients with renal function impairment should not receive magnesium sulfate because it is excreted
exclusively in the urine.
 MgSO4 + Cardiac Ischemia = Contraindicated.
 Patients who have cardiac ischemia should never receive MGSO4 because Magnesium inhibits calcium influx
into cells, decreases systemic vascular resistance and increases cardiac output .
(Lu & Nightingale, 2000) (Virkud,2015)

11.  MGSO4 has been shown to be tolerated well by both mother and fetus when administered and in fact reduces
morbidity and mortality from preeclampsia and eclampsia.
 MGSO4 does need to be monitored prudently in order to prevent adverse reactions from occurring due to the
development of Magnesium toxicity.
 A collaborative effort between patient, pharmacist, medical doctor (MD) and nurse should be continuous to
improve patient care and safety.
(Lu & Nightingale, 2000) (Virkud,2015)

12.  Medical Doctor - Thorough assessment and diagnosis of the patient condition before beginning any
treatment regimen.
 Patient - educate regarding their condition, treatment plan and the side effects of magnesium sulfate are
warranted. Educate on the Speak up program.
 Hospital - have well established protocols in place for dose administration and monitoring of Magnesium
Sulfate.
 Pharmacy - Have regulations in place for mixing, dispensing, and labeling MSO4, plus have the antidote
readily available.
 Nursing – Follow established policies and protocols for assessing and administering MgSO4. MgSO4 is a high
alert medication and orders given and written are not to be abbreviated.
(Virkud, 2015)(Perez, 2017)

13. A TEAM EFFORT
 Collaboration assists in improving patient safety and outcomes. Our team includes everyone working in the
patients care, their family, themselves and any committee involved.
 A hospital task force also needs to keep Magnesium Sulfate and other high alert medications as topics to
discuss in their to review measures that work well and identify areas needing improvement .

14. At KNAPP Medical Center, there is a Pharmacy and Therapeutics Committee that takes into consideration
hospital policies and procedures along with patient safety goals and national guidelines. A protocol has also been
established with parameters for how much an MD should order and at what rate, plus Calcium Gluconate
administration guidelines. The pharmacist premixes MGSO4 and two nurses must sign off at bedside before
beginning administration. It is a high alert medication, labelled as such and Mg labs are monitored every 4 hours
as well as patient clinical symptoms hourly as per policy.
(Perez, 2017).

15.  Established Guidelines - In Form Fast under MGSO4 orders.
 Commonly Ordered - Loading dose of 4grams Magnesium Sulfate in 50ml D5W to infuse over 15 minutes
(pre-mixed). Continuous infusion of 40 grams Magnesium Sulfate in 1000ml of fluid pre-mixed.
 Administration - Two nurses check five medication rights and witness in electronic medication administration.
Given in grams or ml per hour. Infused on a pump in ml per hour. High Alert Infusion.
 -Have Lactated Ringers running as main line and magnesium piggy backed into last port of LR.
 Eclampsia - 4 grams IV push over 3-5 minutes with IV wide open and notify MD STAT
 Calcium Glugonate – 1gram of 10 % solution in 10 millimeters administered slowly over 3-5 minutes as
ordered by physician.

16. HOURLY MONITORING FOR MAGNESIUM TOXICITY
 Patellar Reflexes – Should be +1 or +2. If absent stop Magnesium Sulfate infusion, prepare to give
alert MD.
 Respiratory Rate – Call MD if 14 or less a minute.
 Urine Output – Want at least 100 ml in a four hour period.
EVERY FOUR HOURS:
 Magnesium Sulfate levels checked four hours after administration of loading dose and/or at physician
discretion. (MD may need a reminder as part of our duty as a prudent nurse).
CALCULATE RATE:
D = ordered dose D X V
h = dose on hand h = 50ml per hour for 2 grams an hour
V = Vehicle supplied in
2 grams x 1000ml
40 grams

17. Arcangelo, V. P., Peterson, A. M., Wilbur, V. F., & Reinhold, J. A. (2017). Pharmacotherapeutics for advanced practice:
a practical approach (4th. Ed.). Philadelphia, PA: Lippincott, Williams & Wilkins.
Berdai, M. A., Labib, S., & Harandou, M. (2016). Prolonged neuromuscular block in a preeclamptic patient induced
by magnesium sulfate. The Pan African Medical Journal, 255. doi:10.11604/pamj.2016.25.5.6616
Euser, A.G., Cipolla, M.J. (2009). Magnesium sulfate treatment for the prevention of eclampsia: A brief review.
Retrieved at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663594/
Lu, J. F., & Nightingale, C. H. (2000). Magnesium sulfate in eclampsia and pre-eclampsia: pharmacokinetic principles.
Clinical Pharmacokinetics, 38(4), 305-314. Retrieved at
http://eds.a.ebscohost.comlibproxy.lamar.edu/eds/detail/detail?vid=7&sid=9759fc4b-dfed-4b80-b480-b42a-
32fct25ba49%40sessionmgr4007$bdate=JnpdGU9ZWxpd

18. Mayo Clinic. (n.d.) Preeclampsia. Retrieved at https://www.mayoclinic.org/disease-
conditions/preeclampsia/diagnosis-treatment/drc-20355751
Perez, D. (11.23.17). Personal communication. Knapp Medical Center Pharmacist.
Williams, P.J. & Morgan, L. (2012). The role of genetics in pre-eclampsia and potential pharmacogenomics
interventions. Retrieved at https://www-ncbi-nlm-nih-gov.libproxy.lamar.edu/pmc/articles/PMC3513227/
Virkud, A. (2015, Nov., 21). Magnesium Sulfate in Obstetrics and Gynecology.
https://www.youtube.com/watch?v=aLtQ0Iwt8Q4