Magnesium supplements

decreases calcium influx → prevents early afterdepolarizations (EADs)

• Torsade-de-pointes

• Refractory ventricular tachyarrhythmias (e.g., polymorphic VT)

• Digoxin intoxication

• Eclampsia

• Constipation

• Tocolysis

• Hypotension

• Asystole

• Drowsiness

• Flush

• Loss of reflexes

• Respiratory depression

• Prevention/Control Seizures

• Preeclampsia/Eclampsia

• Hypomagnesemia

• Preterm labor/fetal neuroprotection

• Arrhythmias

• Acute MI

• Acute Asthma

• Barium Poisoning

• Parenteral administration in heart block or myocardial damage.

• Tocolytic therapy in general may be contraindicated by some maternal or fetal conditions (e.g., nonreassuring fetal status, chorioamnionitis, fetal demise, lethal congenital or chromosomal abnormalities, maternal bleeding with hemodynamic instability, severe preeclampsia or eclampsia, preterm premature rupture of membranes [may consider use in the absence of maternal infection for maternal transport and/or corticosteroid administration]).

• Tocolytic therapy with magnesium sulfate may be contraindicated in myasthenia gravis. 

• In toxemia of pregnancy during 2 hours prior to delivery.

Flushing, sweating, hypotension, depression of reflexes, flaccid paralysis, hypothermia, circulatory collapse, depression of cardiac function, CNS depression, respiratory paralysis, hypocalcemia, tetany.

• Hypermagnesemia (serum magnesium concentrations >2.5 mEq/L) may depress the CNS and block peripheral neuromuscular transmission, producing anticonvulsant effects. 

• Exact mechanism is not fully known; excess magnesium appears to decrease the amount of acetylcholine liberated by the motor nerve impulse. 

  Magnesium ions slow the rate of the SA node impulse formation and prolong conduction time in animals. 

• IV infusion prolongs PR interval, H (atria-His bundle) interval, antegrade AV nodal effective refractory period, and SA conduction time in humans. 

• Required cofactor for >300 enzyme systems. 

• Required for both anaerobic and aerobic energy generation and for glycolysis. 

• Described as nature’s physiologic calcium-channel blocking agent. 

• During magnesium depletion, intracellular calcium increases, which can cause muscle cramps, hypertension, and coronary and cerebral vasospasms. 

• Plays an important role in BP regulation; hypertension may be associated with magnesium deficiency and magnesium may decrease BP in hypertension. 

• Important role in bone and mineral homeostasis and can directly affect bone cell formation and influence hydroxyapatite crystal formation and growth; deficiency may be risk factor for osteoporosis.

• Insulin resistance and impaired insulin secretion with deficiency.