MAGNESIUM SULFATE 20% w/v Solution for infusion Ref.[6959] Active ingredients: Magnesium sulfate

Magnesium salts should be administered with caution to patients with impaired renal function and appropriate dosage reduction should be made. See section 4.2.

Magnesium sulfate should not be used in hepatic coma if there is a risk of renal failure.

Respiratory depression may occur and caution is required in patients with respiratory disease.

Parenteral magnesium should be used with caution in individuals with myasthenia gravis, to prevent an exacerbation of the condition or the precipitation of a myasthenic crisis. A risk-benefit assessment should be performed in individual cases prior to initiation of treatment.

Serum calcium levels should be routinely monitored in patients receiving magnesium sulfate.

Muscle Relaxants: non-depolarising muscle relaxants such as tubocurarine are enhanced by parenteral magnesium salts.

Nifedipine: profound hypotension was produced in two women who were given oral Nifedipine.

Magnesium salts should also be administered with caution to those receiving digitalis glycosides.

Parenteral administration of magnesium salts may enhance the effects of neuromuscular blocking agents or of central nervous system depressants. The neuromuscular blocking effects of parenteral magnesium and aminoglycoside antibacterials may be additive.

CNS Depressants: When barbiturates, opiates, general anaesthetics, or other CNS depressants are administered concomitantly with magnesium sulfate, dosage of these agents must be carefully adjusted because of the additive central depressant effects.

Intravenous calcium will antagonise the effects of magnesium.

The muscle stimulating effects of barium toxicity are reduced by magnesium.

Pregnancy

As eclampsia may be life-threatening to mother and baby, magnesium sulfate may be administered in this condition.

Magnesium crosses the placenta and may produce hypotonia, hypoflexia, hypotension. If administered during labour it may cause respiratory depression of the newborn infant. When used in pregnant women, fetal heart rate should be monitored and use within 2 hours of delivery should be avoided.

Breastfeeding

Safety during breast feeding has not been established. Therefore, as with all drugs, it is not advisable to administer magnesium sulfate during breastfeeding unless considered essential.

Fertility

There is no information on the effects of magnesium sulfate on fertility.

Not relevant.

Immune system disorders: Hypersensitivity reactions.

Excessive administration of magnesium leads to the development of symptoms of hypermagnesaemia which may include:

Metabolism and Nutritional disorders: Electrolyte/fluid abnormalities (hypophosphataemia, hyperosmolar dehydration)

Nervous system disorders: Respiratory depression, Nausea, vomiting, drowsiness and confusion
Coma, Slurred speech, double vision

Cardiac disorders: Cardiac arrhythmias, cardiac arrest, ECG changes (prolonged PR, QRS and QT intervals), bradycardia

Vascular disorders: Flushing of the skin and hypotension due to peripheral vasodilatation

Musculoskeletal and connective tissue disorders: Loss of tendon reflexes due to neuromuscular blockade, muscle weakness

Other undesirable effects: Thirst

There have been isolated reports of maternal and foetal hypocalcaemia with high doses of magnesium sulfate.

Especially in patients with impaired renal function, there may be sufficient accumulation of magnesium sulfate to produce toxic effects.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme. Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.

This medicinal product must not be mixed with other medicinal products except those mentioned in section 6.6.