Magnesium Sulphate Injection 50%

Magnesium Sulphate BP 50% w/v

Sterile solution for parenteral use.

Treatment of magnesium deficiency where the oral route of administration may be inappropriate, which may be due to malabsorption syndromes, chronic alcoholism, malnutrition, severe diarrhoea or patients on total parenteral nutrition.

Magnesium sulphate injection may be administered by intramuscular or intravenous routes. For intravenous administration, a concentration of 20% or less should be used; the rate of injection not exceeding 1.5ml/minute of a 10% solution or its equivalent.

Adults

The dosage should be individualised according to patient's needs and responses.

Mild magnesium deficiency

1g intramuscularly every 6 hours for 4 doses.

Severe magnesium deficiency

Up to 250mg/kg intramuscularly given over 4 hours or 5g/litre of infusion solution intravenously over 3 hours.

Children

It is recommended that the solution be diluted to 20% w/v prior to intramuscular injection.

Elderly

No special recommendations.

Magnesium sulphate is contraindicated in patients with heart block, myocardial damage or impaired renal function.

Magnesium sulphate must be used with caution in patients suspected of or known to have renal impairment.

Administer with caution to patients receiving digitalis glycosides. Effects of neuromuscular blocking agents may be enhanced. Magnesium sulphate should not be administered concomitantly with high doses of barbiturates, opioids or hypnotics due to the risk of respiratory depression.

Concomitant use of nifedipine may very rarely lead to a calcium ion imbalance and could result in abnormal muscle function.

Safety in human pregnancy and during breastfeeding has not been established, therefore, as with all drugs it is not advisable to administer magnesium sulphate during pregnancy or breastfeeding unless considered essential, and it must be administered under medical supervision.

None known.

Hypermagnesaemia characterised by flushing, thirst, hypotension, drowsiness, nausea, vomiting, confusion, loss of tendon reflexes due to neuromuscular blockade, muscle weakness, respiratory depression, cardiac arrhythmias, coma and cardiac arrest.

There is a risk of respiratory depression if magnesium sulphate is administered concomitantly with high doses of barbiturates, opioids or hypnotics (see 'Interactions').

Symptoms: Hypermagnesaemia characterised by flushing, thirst, hypotension, drowsiness, nausea, vomiting, confusion, loss of tendon reflexes due to neuromuscular blockade, muscle weakness, respiratory depression, cardiac arrhythmias, coma and cardiac arrest.

Treatment: Maintain respiration with 10% calcium gluconate administered intravenously in a dose of 10-20ml. If renal function is normal adequate fluids should be given to assist removal of magnesium from the body. Dialysis may be necessary in patients with renal impairment or severe hypermagnesaemia.

Magnesium is the second most abundant cation in intracellular fluid and is an essential body electrolyte. Magnesium is a factor in a number of enzyme systems, and is involved in neurochemical transmission and muscular excitability.

Parenterally administered magnesium sulphate exerts a depressant effect on the central nervous system and acts peripherally to produce vasodilation.

Following intravenous administration, the onset of action is immediate and the duration approximately 30 minutes. Following intramuscular administration the onset of action occurs after approximately one hour and the duration of action is 3-4 hours.

Magnesium sulphate is excreted by the kidneys with small amounts being excreted in breast milk and saliva.

None stated.

Sodium hydroxide BP

Sulphuric acid BP

Water for injections HSE

Magnesium sulphate is incompatible with alkali hydroxides (forming insoluble magnesium hydroxide), alkali carbonates (forming insoluble magnesium carbonate) and salicylates. Streptomycin sulphate and tetramycin sulphate activity is inhibited by magnesium ions.

36 months.

Store below 25°C.

Neutral Type I glass ampoules containing 2ml, 4ml or 40ml, supplied in packs of 1, 5 or 10 units.

Not all pack sizes may be marketed.

None stated.

UCB Pharma Limited

208 Bath Road

Slough

Berkshire

SL1 3 WE

UK

PL 00039/5903R

2 June 1987 / 3 September 1997

June 2005