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MAGNESIUM SULPHATE 50% W/V SOLUTION FOR INJECTION

Active substance(s): MAGNESIUM SULPHATE HEPTAHYDRATE

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PATIENT INFORMATION LEAFLET
Magnesium Sulphate 50% w/v Solution for injection
Magnesium Sulphate (as heptahydrate) 1g in 2ml, 5g in 10ml
This leaflet contains important information about Magnesium Sulphate Injection. Read
all of this leaflet carefully before you start your treatment with this medicine.
1. Keep this leaflet. You may need to read it again.
2. If you have further questions, please ask your doctor.
3. If any of the side effects get serious, or if you notice any side effects not listed in this
leaflet, please tell your doctor or nurse.
In this leaflet
1. What is Magnesium Sulphate Injection and what is it for
2. Before you are given Magnesium Sulphate Injection
3. How Magnesium Sulphate Injection is used
4. Possible side effects
5. How Magnesium Sulphate Injection is stored
6. Further information
1. What is Magnesium Sulphate Injection and what is it for
The name of your medicine is Magnesium Sulphate 50% w/v – solution for injection. It is a
sterile solution containing magnesium sulphate (as heptahydrate). It also contains water and
may also contain a very small amount of hydrochloric acid and/or sodium hydroxide.
The product is available in 2ml and 10ml ampoules in packs of 10 ampoules. It will be
administered by a health care professional and may be diluted first.
Magnesium sulphate is a mineral salt which is given to:
• increase the amount of magnesium in the body in conditions where, because of a variety of
causes, the blood level of magnesium is below normal.
• prevent further fits (seizures) occurring because of very high blood pressure in pregnancy
(eclampsia).
2. Before you are given Magnesium Sulphate Injection
Magnesium Sulphate Injection should not be used if you:

You are very sensitive to magnesium salts

You have liver problems (particularly in hepatic coma if there is a risk of kidney
failure)
Take special care with magnesium sulphate if:
• You have kidney problems, although a reduction in the usual dosage may be appropriate.
• You suffer from myasthenia gravis (a rare condition causing muscle weakness)
• If you are taking or using other drugs – see ‘Taking other medicines’ below.
Always tell your doctor or nurse about any of these before having your injection.
Taking other medicines

Tell your doctor if you are taking or have recently taken any medicines including medicines
obtained without a prescription. Magnesium Sulphate can interfere with the action of some
other drugs and some drugs can have an effect on Magnesium Sulphate. The following drugs
can cause some problems when taken together with Magnesium Sulphate Injection:
• Opioids such as morphine or codeine, barbiturates such as amylobarbitone or hypnotics
such as nitrazepam or temazepam.
• Muscle relaxants such as tubocurarine, used during anaesthesia
• Nifedipine or nimodipine which may be used to treat high blood pressure or chest pain
(angina), as using this medicine with Magnesium Sulfate can cause problems with muscle
function
• Digoxin for the treatment of heart failure or irregular heart beats
• Suxamethonium used for anaesthesia.
• Aminoglycoside antibacterial medicines (such as streptomycin).
Pregnancy and breast-feeding
• Magnesium crosses the placenta and so can reach your baby.
However, your doctor may decide to use it if you are pregnant and have very high blood
pressure (eclampsia). This is because you are a risk of having fits (seizures). In this case,
the treatment is considered less harmful than the fits.
If you are being treated with magnesium sulphate for other conditions, then tell your
doctor if you are pregnant, think you might be pregnant or are trying to become pregnant.
• If you are breast feeding you should tell your doctor before you are given this medicine.
Small amounts of magnesium get into breast milk.
Driving and using machines
Your medicine is unlikely to affect your ability to drive or to operate machinery. However,
some people may feel dizzy or drowsy when given Magnesium Sulphate injection. If this
happens to you, do not drive or operate machinery.
3. How Magnesium Sulphate Injection is used
Magnesium sulphate will be given to you by injection either into a muscle (intramuscularly)
or into a vein (intravenously) after being diluted. The dose depends on your individual needs
and responses to treatment. Your blood levels will be monitored during treatment. If you have
doubts about the treatment or want more information about your medicine or the monitoring
procedure, do ask the doctor or nurse.
Treatment of magnesium deficiency (hypomagnesaemia)
Adults:
Up to 40g magnesium sulphate by slow intravenous (IV) infusion (in glucose 5% or normal
saline) over a period of up to five days.
Children:
Administer diluted into a muscle.
Elderly:
As for adults.
To prevent further seizures associated with very high blood pressure in pregnancy
(eclampsia)
Adult women:

An initial IV loading dose followed either by intravenous infusion or by regular
intramuscular (IM) injections for 24 hours.
IV Maintenance Regimen
A loading dose of 4-5g (usually as a 20% solution) over 5-15 minutes, followed by an
infusion of 1g/hour continuing for 24 hours after the last fit.
IM Maintenance Regimen
The IV loading dose is followed immediately by 5g (usually as a 50% or 25% solution) by
deep IM injection into the upper outer quadrant of each buttock.
Maintenance therapy is a further 5g IM every four hours, continued for 24 hours after the last
fit.
Recurrent convulsions: In both IV and IM regimens, a further 2-4g IV over a period of 5
minutes.
If more Magnesium Sulphate is used than should be:
Excessive administration of magnesium leads to the development of hypermagnesaemia, i.e.
high blood levels of magnesium. Hypermagnesaemia may only be associated with mild
symptoms initially – see “Possible side effects” below – but if treatment is not terminated or
efforts made to reduce the blood level, symptoms may become more serious and could lead
eventually to coma or cardiac arrest. You may require an injection of a calcium salt to
counteract an excessively high level of magnesium.
Tell the doctor if you are experiencing any side effects or think you may be reacting badly so
that he/she can give appropriate treatment.
If you have already left the medical premises, contact your nearest hospital, doctor or nurse.
If you miss a dose of Magnesium Sulphate:
It is unlikely that you will miss a dose as your doctor or nurse will be giving it to you.
However, it is important not to have a double dose if you have missed one. Ask your doctor
or nurse when you should have the next dose.
If you have any further questions on the use of this product, ask your doctor or nurse.
4. Possible side effects
Like all medicines, Magnesium Sulphate can cause side effects although not everyone gets
them.
Seek immediate medical help if you have an allergic reaction. This included any of the
following symptoms:
• Difficulty in breathing, - slow and/or shallow breathing
• Swelling of your eyelids, face or lips
• Rash or itching especially those covering your whole body.
Nervous System disorders






Feeling sick (nausea)
Vomiting
Drowsiness
Feeling confused
Coma

• Slurred speech
• Double vision
Heart Problems
• Drop in blood pressure
• Flushing of the skin
• Irregular heart beats
• Heart attack
Other effects
• loss of the knee jerk reflex
• muscle weakness
• feeling thirsty
• low blood calcium levels in pregnant women and their developing babies have been
reported extremely rarely
• Low levels of calcium in your blood. (This may cause you to have pins and needles or
twitching muscles)
If any of the side effects get serious, or if you notice any side effects not listed in this leaflet,
please tell your doctor or nurse.
Reporting of side effects
If you get any side effects, talk to your doctor or pharmacist or nurse. This includes any
possible side effects not listed in this leaflet. You can also report side effects directly via the
national reporting system (Yellow Card Scheme Website: www.mhra.gov.uk/yellowcard). By
reporting side effects you can help provide more information on the safety of this medicine.
5. How Magnesium Sulphate Injection is stored
• Do not store above 30°C.
• Keep this medicine out of the sight and reach of children
• Do not use Magnesium Sulphate Injection after the expiry date which is stated on the
ampoule and carton after (Exp:MM/YYYY). The expiry date refers to the last day of that
month.
• Do not throw away any medicines via wastewater or household waste. Ask your
pharmacist how to throw away medicines you no longer use. These measures will help
protect the environment.
6. Further information
Magnesium Sulphate Injection is a sterile solution for injection containing magnesium
sulphate (as heptahydrate). It also contains water and may also contain a very small amount
of hydrochloric acid and/or sodium hydroxide.
The product is available in 2ml and 10ml ampoules in packs of 10 ampoules
The Marketing Authorisation for Magnesium Sulphate Injection is held by Auden Mckenzie
(Pharma Division) Ltd, Mckenzie House, Bury Street, Ruislip, Middlesex, HA4 7TL, UK.
Magnesium Sulphate Injection is manufactured by SNS Pharmaceuticals Ltd., Mckenzie
House, Bury Street, Ruislip, Middlesex, HA4 7TL, UK.

This leaflet was revised in April 2016
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SUMMARY OF PRODUCT CHARACTERISTICS
(Please detach prior to giving the leaflet to the patient)
Magnesium Sulphate 50% w/v Solution for Injection
Magnesium sulphate as heptahydrate 1g in 2ml, 5g in10ml

1

NAME OF THE MEDICINAL PRODUCT
Magnesium Sulphate 50% w/v Solution for Injection

2

QUALITATIVE AND QUANTITATIVE COMPOSITION
Magnesium sulphate as heptahydrate 1g/2ml, 5g/10ml
For excipients, see Section 6.1

3

PHARMACEUTICAL FORM
Solution for injection

4

CLINICAL PARTICULARS

4.1

Therapeutic indications
Treatment of magnesium deficiency in hypomagnesaemia
Prevention of recurrent seizures in eclampsia

4.2

Posology and method of administration
Magnesium sulphate may be administered by the intramuscular or intravenous routes.
For the intravenous route (and also for the intramuscular route in children), the
solution requires dilution to a concentration of not more than 20%. Glucose 5% (or
sodium chloride 0.9%) is a suitable dilution fluid.
Dosage should be tailored according to the individual’s needs and responses and
should be reduced in renal impairment. Plasma magnesium concentrations should be
measured to determine the rate and duration of infusion and should be monitored
throughout therapy.
Treatment of magnesium deficiency in hypomagnesaemia
Adults:

Up to 160mmol Mg++ (provided by approximately 40g magnesium sulphate [as
heptahydrate]/80ml of a 50% solution) by slow intravenous infusion of a diluted
solution over a period of up to five days.
Children:
Dilute appropriately and administer by the intramuscular route.
Elderly:
There are no specific recommendations for dosage in elderly adults.
Prevention of recurrent seizures in eclampsia
Adult women:
An initial IV loading dose followed either by intravenous infusion or by regular IM
injections for 24 hours.
IV Maintenance Regimen
A loading dose of approximately 16mmol Mg++ (provided by 4-5g magnesium
sulphate [as heptahydrate], usually as a 20% solution) over 5-15 minutes, followed by
an infusion of approximately 4mmol Mg++ (1g) every hour for at least 24 hours after
the last fit.
IM Maintenance Regimen
The IV loading dose is followed immediately by 5g magnesium sulphate [as
heptahydrate], using either the 50% solution provided or a dilution to 25%, as a deep
IM injection into the upper outer quadrant of each buttock.
Maintenance therapy is a further 5g IM every four hours, continued for 24 hours after
the last fit (provided respiratory rate is >16/min, urine output >25ml/min and knee
jerks are present).
Recurrent convulsions: In both IV and IM regimens, a further 2-4g depending on
body weight (2g if less than 70g) is given IV over a period of 5 minutes.
A reduction in dosage (20g over 48 hours) should be made for patients with severe
renal impairment.

4.3

Contraindications
Hypersensitivity to magnesium and its salts
Hepatic encephalopathy, hepatic failure, renal failure

4.4

Special warnings and precautions for use
Magnesium salts should be administered with caution to patients with impaired renal
function and appropriate dosage reduction should be made.
Magnesium sulphate should not be used in hepatic coma if there is a risk of renal
failure.
Parenteral magnesium salts should be used with caution in patients with myasthenia
gravis.
Serum calcium levels should be routinely monitored in patients receiving magnesium
sulphate.

The solution MUST be diluted before use for IV administration; concentrations up to
20% w/v are usually employed. For IM use, a 25% w/v or 50% w/v solution is
acceptable.

4.5

Interaction with other medicinal products and other forms of interaction
Muscle relaxants
The action of non-depolarising muscle relaxants such as tubocurarine is potentiated
and prolonged by parenteral magnesium salts.
Nifedipine
Profound hypotension has been reported.
Concomitant use of calcium channel blockers such as nimodipine or nifedipine may
rarely lead to a calcium ion imbalance and could result in abnormal muscle function.
Magnesium salts should also be administered with caution to those patients receiving digitalis
glycosides.
Parenteral administration of magnesium salts may enhance the effects of neuromuscular
blocking agents. The neuromuscular blocking effects of parenteral magnesium and
aminoglycoside antibacterials may be additive.

There is a risk of respiratory depression if magnesium sulphate is administered
concomitantly with high doses of barbiturates, opioids or hypnotics

4.6

Pregnancy and lactation
As eclampsia may be life-threatening to mother and baby, magnesium sulphate may
be administered in this condition.
Magnesium crosses the placenta. When used in pregnant women, foetal heart rate
should be monitored and use within 2 hours of delivery should be avoided.
Safety during breast feeding has not been established. Therefore, as with all drugs, it
is not advisable to administer magnesium sulphate during lactation unless considered
essential.

4.7

Effects on ability to drive and use machines
None known

4.8

Undesirable effects

Immune system disorder:
Hypersensitivity reactions.

Excessive administration of magnesium leads to the development of symptoms of
hypermagnesaemia which may include:
Metabolism and Nutritional disorder
Electrolyte/fluid abnormalities (hypophosphataemia, hyperosmolar dehydration)

CNS effects
Respiratory depression
Nausea, vomiting, drowsiness and confusion
Coma
Slurred speech, double vision

Cardiovascular effects
Flushing of the skin and hypotension due to peripheral vasodilatation
Cardiac arrhythmias, cardiac arrest
ECG changes (prolonged PR, QRS and QT intervals), bradycardia
Other undesirable effects
Loss of tendon reflexes due to neuromuscular blockade, muscle weakness, thirst
There have been isolated reports of maternal and foetal hypocalcaemia with high
doses of magnesium sulphate.
Especially in patients with impaired renal function, there may be sufficient
accumulation of magnesium sulphate 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 national reporting system (Yellow Card Scheme Website:
www.mhra.gov.uk/yellowcard)
4.9

Overdose
Signs:
Clinical signs of overdosage will be those of hypermagnesaemia – see Section 4.8.
Patients with renal failure and metabolic derangements develop toxicity at lower
doses.
Treatment:

Appropriate action should be taken to reduce the blood level of magnesium.
Neuromuscular blockade associated with hypermagnesaemia may be reversed with
calcium salts, such as calcium gluconate, which should be administered intravenously
in a dose equivalent to 2.5 to 5mmol of calcium.

5

PHARMACOLOGICAL PROPERTIES

5.1

Pharmacodynamic properties
Magnesium is the second most abundant cation in intracellular fluid and is an
essential body electrolyte. It is a cofactor in numerous enzyme systems and is
involved in phosphate transfer, muscle contractility and neuronal transmission. The
body contains about 25g of magnesium (about 14mmol per kg body weight),
approximately 60% of which is found in the skeleton. The daily amount of
magnesium required by an adult is of the order of 270 to 350mg (about 11 to
14mmol).
The normal concentration of magnesium in plasma is around 0.65 to 1.0mmol/l.
Serum magnesium levels in the range 1.5 – 2.5mmol/l cause vasodilatation in the
peripheral and coronary circulation and corresponding increases of 20-25% in cardiac
output and coronary blood flow. There is little change in heart rate or blood pressure.
Animal studies suggest that the effect of magnesium ions on cardiac muscle is to slow
the rate of the sinoatrial node impulse formation and prolong conduction time.
Limited data on patients with no evidence of heart disease indicate that intravenous
magnesium prolongs PR interval, H (atria-His bundle) interval, antegrade AV nodal
effective refractory period and sinoatrial conduction time. Within this concentration
range there are no detectable effects on CNS function or neuromuscular transmission.
At a serum magnesium level of 1-3mmol/l, platelet disaggregation has been reported;
possibly mediated by stimulation of prostacyclin release from vascular endothelium.
At plasma concentrations up to 4mmol/l, the only adverse effect likely to be seen is
flushing due to peripheral vasodilalation. At about 4-5mmol/l, concentrationdependent toxicity is heralded by loss of deep tendon reflexes, then successively by
hypotension, bradycardia and ultimately neuromuscular blockade leading to
respiratory arrest.

5.2

Pharmacokinetic properties
The approximate amount of magnesium each g of magnesium sulphate heptahydrate
will provide is 4.1mmol ≡ 8.1mEq and 2ml of a 50% w/v solution will therefore
provide 4mmol of magnesium ions.
When given intravenously, magnesium sulphate has an immediate onset of action and
its duration of activity is about 30 minutes. The onset of action of intramuscular
magnesium sulphate is about one hour and its duration of action 3-4 hours.
Small and clinically irrelevant amounts of magnesium are excreted in milk. The major
excretory pathway is renal and parenteral loads are rapidly eliminated in this way. In
renal impairment, there may be accumulation of magnesium. Faecal loss is very
limited; small amounts are excreted in saliva and magnesium crosses the placenta.

5.3

Preclinical safety data
There are no preclinical data of relevance to the prescriber additional to those already
included in other sections of the SPC.

6

PHARMACEUTICAL PARTICULARS

6.1

List of excipients
Water for Injections
Hydrochloric Acid
Sodium Hydroxide

6.2

Incompatibilities
Magnesium sulphate is incompatible with alkali hydroxides (forming insoluble
magnesium hydroxide), alkali carbonates (forming insoluble magnesium carbonate)
and salicylates. The activities of streptomycin sulphate and tetramycin sulphate are
inhibited by magnesium ions.

6.3

Shelf life
36 months

6.4

Special precautions for storage
Do not store above 30oC

6.5

Nature and contents of container
2ml and 10ml clear glass (Ph. Eur. Type I) ampoules containing a 50% w/v solution
of magnesium sulphate as heptahydrate for injection.
Pack size: 10 ampoules per carton.

6.6

Special precautions for disposal
For intramuscular use, a 25% w/v or 50% w/v solution is used. For intravenous use,
the solution must be diluted before use; concentrations up to 20% w/v are usually
employed.
Any solution remaining at the end of administration should be discarded in an
appropriate manner.

7

MARKETING AUTHORISATION HOLDER
Auden Mckenzie (Pharma Division) Ltd
Mckenzie House
Bury Street

Ruislip
Middlesex
HA4 7TL
UK

8

MARKETING AUTHORISATION NUMBER(S)
PL 17507/0025

9

DATE OF FIRST AUTHORISATION/RENEWAL OF THE
AUTHORISATION
25/04/2003

/

20/03/2009

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Source: Medicines and Healthcare Products Regulatory Agency

Disclaimer: Every effort has been made to ensure that the information provided here is accurate, up-to-date and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. This information has been compiled for use by healthcare practitioners and consumers in the United States. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate that the drug or combination is safe, effective or appropriate for any given patient. If you have questions about the substances you are taking, check with your doctor, nurse or pharmacist.

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