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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
• Muscle relaxants such as tubocurarine, used during
1. W
 hat is Magnesium Sulphate
anaesthesia
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.
•p
 revent further fits (seizures) occurring because of very
high blood pressure in pregnancy (eclampsia).

2. B
 efore you are given Magnesium Sulphate
Injection
Magnesium Sulphate Injection should not be used if you:
•Y
 ou are very sensitive to magnesium salts
•Y
 ou 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.
• I f 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:
•O
 pioids such as morphine or codeine, barbiturates such as
amylobarbitone or hypnotics such as nitrazepam or
temazepam.

A1000065_1 V1 Magnesium 50% PIL.indd 1

• Nifedipine which may be used to treat high blood pressure
or chest pain (angina)
• 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.

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 in 10ml
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.
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.
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

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To prevent further seizures associated with very high blood
pressure in pregnancy (eclampsia)
Adult women: A
 n initial IV loading dose followed either by
intravenous infusion or by regular
intramuscular (IM) injections for 24 hours.

Heart Problems
•D
 rop in blood pressure
•F
 lushing of the skin
• Irregular heart beats
•H
 eart attack

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.

Other effects
• L oss of the knee jerk reflex
•M
 uscle weakness
•F
 eeling thirsty
• L ow blood calcium levels in pregnant women and their
developing babies have been reported extremely rarely
• L ow levels of calcium in your blood. (This may cause you
to have pins and needles or twitching muscles)

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. P
 ossible side effects

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
•D
 o not store above 30°C.
•K
 eep this medicine out of the sight and reach of children
•D
 o 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.
•D
 o 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.

Like all medicines, Magnesium Sulphate can cause side
effects although not everyone gets them.

The product is available in 2ml and 10ml ampoules in packs
of 10 ampoules

Seek immediate medical help if you have an allergic reaction.
This included any of the following symptoms:
•D
 ifficulty in breathing, - slow and/or shallow breathing
•S
 welling of your eyelids, face or lips
•R
 ash or itching especially those covering your whole body.

The Marketing Authorisation for Magnesium Sulphate
Injection is held by Auden Mckenzie (Pharma Division) Ltd,
Mckenzie House, Bury Street, Ruislip, Middlesex, HA4 7TL,
UK.

Nervous System disorders
•F
 eeling sick (nausea)
•V
 omiting
•D
 rowsiness
•F
 eeling confused
•C
 oma
•S
 lurred speech
•D
 ouble vision

Magnesium Sulphate Injection is manufactured by SNS
Pharmaceuticals Ltd., Mckenzie House, Bury Street, Ruislip,
Middlesex, HA4 7TL, UK.
This leaflet was revised in April 2014

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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.

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.

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).

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.

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.

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 30°C
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
10 DATE OF REVISION OF THE TEXT
27/08/2009

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, concentration-dependent 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.

Auden Mckenzie (Pharma Division) Ltd

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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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