• Clinical Info

Interactions

Specific Drugs

Pharmacokinetics

Absorption

Onset

IV administration: Immediate onset.

IM administration: About 1 hour.

Duration

IV administration: About 30 minutes.

IM administration: 3–4 hours.

Plasma Concentrations

Effective anticonvulsant serum magnesium concentrations: 2.5–7.5 mEq/L.

Monitor for hypermagnesemia (serum concentrations >2.5 mEq/L); toxic effects (e.g., depression of deep-tendon reflexes) may begin at 4 mEq/L.

At 10 mEq/L, deep-tendon reflexes disappear and respiratory paralysis may occur; complete heart block can occur at about 10 mEq/L.

Serum magnesium >12 mEq/L may be fatal.

Distribution

Extent

Crosses the placenta.

Distributes into milk.

Elimination

Elimination Route

Excreted by the kidneys; interindividual variability in rate but directly proportional to serum concentration and glomerular filtration.

Stability

Storage

Parenteral

Injection

15–30°C.

Magnesium Sulfate in 5% Dextrose Injection

25°C (may expose to up to 40°C). Avoid freezing.

Compatibility

For information on systemic interactions resulting from concomitant use, see Interactions.

Incompatible with alkali hydroxides (forming insoluble magnesium hydroxide), with alkali carbonates (forming basic carbonates), and with salicylates (forming basic salicylates).

Reacts with arsenates, phosphates, and tartrates, precipitating the corresponding magnesium salts.

Lead, barium, strontium, and calcium react with magnesium sulfate resulting in precipitation of the respective sulfates.

Parenteral

Solution Compatibility

Drug Compatibility