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Active substance(s): PHENYTOIN SODIUM

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Special care needs to be taken with
Phenytoin Injection

Phenytoin Injection BP
Read all of this leaflet carefully before
you start using this medicine.
• Keep this leaflet. You may need to
read it again.
• If you have any further questions, ask
your doctor or pharmacist.
• If any of the side effects gets serious,
or if you notice any side effects not
listed in this leaflet, please tell your
In this leaflet:
1. What Phenytoin Injection is and what it is
used for
2. Before Phenytoin Injection is used
3. How Phenytoin Injection is used
4. Possible side effects
5. How Phenytoin Injection is stored
6. Further information

Phenytoin is one of a group of medicines
called hydantoins.
Phenytoin Injection is a medicine which is
used to control status epilepticus (serious
condition in which seizures (fits) continue
for hours or days) or to prevent fits during
or after neurosurgery. It can also be used to
correct some heart rhythm abnormalities.

Phenytoin Injection should not be used
• if you have shown signs of hypersensitivity
(severe allergy) to phenytoin, any of the
ingredients of phenytoin Injection, or
medicines of the same class (hydantoins)
in the past
• in patients with certain heart conditions
If possible, tell your doctor if any of the
above applies to you before this medicine is
This medicine must not be injected into an
artery. See section 3 for the correct method
of administration.

Take special care with Phenytoin
A small number of people being treated with
anti-epileptics such as phenytoin have had
thoughts of harming or killing themselves.
If at any time you have these thoughts,
immediately contact your doctor.
Serious skin side effects can rarely occur
during treatment with Phenytoin Injection.
This risk may be associated with a variant
in genes in a subject of Chinese or Thai
origin. If you are of such origin and have
been tested positively carrying this genetic
variant (HLA-B*1502), discuss this with your
doctor before taking Phenytoin Injection.
Some evidence suggests that black
patients are also at increased risk of these
reactions. In the Caucasian and Japanese
population frequency of the genetic variant
(HLA-B*1502) is extremely low therefore
risk of developing serious skin side effects
cannot be concluded.
A combination of phenytoin, radiation
therapy to the head and gradual reduction in
treatment with corticosteroids may also be
associated with the development of serious
skin side effects.
Irritation and swelling can occur at and
around the site of injection with phenytoin.
Build up of fluid beneath the skin, change in
colour of the skin and pain may also occur
following peripheral intravenous phenytoin
In rare cases, patients taking phenytoin
have experienced problems with their
internal organs. Outward signs include fever,
rash and swollen lymph nodes (isolated
small raised lumps under the skin) within
2-12 weeks of beginning treatment. The risk
may be increased in black patients, patients
who have a family history of or who have
experienced these problems in the past and
those with decreased ability to fight infections
(also known as immunosuppression).

Phenytoin Injection BP
The following information is intended for
medical or healthcare professionals only
Practical information on the preparation/handling
of the medicinal product is provided here.
Intra-arterial administration must be avoided
in view of the high pH of the preparation.
Improper administration including
subcutaneous or perivascular injection
should be avoided.

if you have a liver or kidney disorder
if you suffer from diabetes
if you suffer from low blood pressure
if you suffer from heart problems
if you have a condition called prophyria

If possible, tell your doctor if any of the
above applies to you before this medicine is

Taking/using other medicines
Special care is needed if you are
taking/using other medicines as some could
interact with phenytoin, for example:
• some antibacterials e.g. doxycycline,
ciprofloxacin, chloramphenicol, isoniazid,
rifampicin, and other sulphonamides
• some antifungals i.e. amphotericin B,
ketoconazole, fluconazole, miconazole
and itraconazole
• some coumarin anticoagulants,
e.g. warfarin and dicoumarol
• medicines used to control diabetes
e.g. insulin or oral anti-diabetic agents
(eg tolbutamide)
• some pain killers and anti-inflammatory
medicines, i.e. phenylbutazone and
salicylates such as aspirin
• some medicines used to control anxiety,
e.g. chlordiazepoxide, diazepam
• barbiturates, e.g. phenobarbitone and
• corticosteroids (used in numerous
situations to aid the body’s healing
• some medicines used to treat
mental problems such as psychoses
and depression, e.g. haloperidol,
methylphenidate, monoamine oxidase
inhibitors, trazodone, thioxanthenes,
fluoxetine, fluvozamine, sertraline and
tricyclic antidepressants
• oral contraceptives and other medicines
which mimic female hormones,
e.g. oestrogen and ethinyloestradiol
• antiepileptic medicines, e.g.
carbamazepine, ethosuximide,
mephenytoin, primidone, sodium
valproate, sulthiame, valproic acid,
oxcarbazepine and trimethadione
• halothane (an inhaled general
• some anti-ulcer medicines, e.g. cimetidine
and ranitidine
• medicines taken to help the heart, i.e.
aspirin, beta-blockers, diazoxide, digoxin,
diltiazem, disopyramide, dopamine,
frusemide, mexiletine, nifedipine,
quinidine, reserpine, amiodarone and
• medicines often taken while undergoing
cancer treatment, i.e. bleomycin, calcium
folinate, carboplatin, carmustine, cisplatin,
dacarbazine, fluorouracil and vinblastine
• St John’s wort - The herbal remedy
St John’s wort (Hypericum perforatum)
should not be taken at the same time
as this medicine. If you already take St
John’s wort, consult your doctor before
stopping the St John’s wort preparations
• nelfinavir, used in the treatment of HIV
• others which you may recognise by name:
ciclosporin, disulfiram, folic acid, L-dopa,
lignocaine, succinimide, viloxazine,
theophylline (a xanthine), methotrexate,
omeprazole, ticagrelor and vitamin D
If possible, please tell your doctor if you
are taking or have recently taken any other
medicines, including medicines obtained
without a prescription.

Phenytoin and alcohol consumption
The consumption of alcohol, whilst you are
being treated with phenytoin can reduce the
effectiveness of treatment or increase the
side effects.

Pregnancy and breast-feeding
This medicine can have negative effects
on unborn children and the injectable form
will only be used if the baby is at risk from
the mother’s convulsions (eg in status
epilepticus). Tell your doctor if you are
pregnant, trying to become pregnant or
breast-feeding. Your doctor will only use this
medicine if the expected benefits outweigh
any potential risk to your baby.

Phenytoin is used for newborns, infants and
Ask your doctor or pharmacist for advice
before taking any medicine.
Intramuscular phenytoin administration may
cause pain, necrosis and abscess formation
at the injection site.

Incompatible with amikacin sulphate, cephapirin
sodium, clindamycin phosphate, and many other
drugs. It is recommended that phenytoin sodium
is not mixed with other drugs or with any infusion
solution other than sodium chloride 0.9%.

Driving and using machines
Do not drive or use machines if you experience
any side effect (e.g. dizziness or drowsiness)
which may lessen your ability to do so.

Important information about some of
the ingredients of Phenytoin Injection
This medicinal product contains 10% vol
ethanol (alcohol), i.e. up to 1.6 g per 1 g dose
of phenytoin, equivalent to 57 ml of a 3.5% vol
beer or 14 ml of a 14% vol wine. Harmful to
those suffering from alcoholism. To be taken
into account in pregnant or breast-feeding
women, children and high-risk groups such as
patients with liver disease or epilepsy.
In addition, this medicinal product contains
propylene glycol, which can cause
alcohol-like symptoms and sodium (1.1 mmol
per 5 ml ampoule).

This medicine will be given to you by a slow
injection via a drip into a vein or, more rarely,
via an injection into a muscle.

Your doctor will calculate the correct does of
phenytoin for you.
The dose will depend upon your medical
condition, your size, your age and how well
your kidneys, liver and heart are working. Your
doctor will tell how well your liver and kidneys
are working from blood and urine samples.
Where treatment is prolonged, blood
samples may be taken to check the level of
phenytoin in the blood. Subsequent doses
may be increased or decreased accordingly.

If you are given too much or too little
Phenytoin Injection
As this medicine will be given to you whilst
you are in hospital it is unlikely that you will be
given too little or too much, however tell your
doctor or pharmacist if you have any concerns.

Effects when treatment with phenytoin is
Sudden withdrawal of phenytoin treatment in
patients susceptible to fits may cause status
epilepticus. In such cases, phenytoin dosage
reduction should be gradual, perhaps
following a switch to a form of phenytoin
which can be taken by mouth.

Like all medicines, phenytoin can cause side
effects, although not everybody gets them.

If any of the following happen, tell your
doctor immediately:
• severe allergic reaction - you may
experience a sudden itchy rash (hives),
swelling of the hands, feet, ankles, face,
lips, mouth or throat (which may cause
difficulty in swallowing or breathing), and
you may feel you are going to faint
• rash (can be severe resulting in painful
reddening and blistering of the skin, eyes,
inside of the mouth and ano-genital region
and may lead to skin shedding)
• swollen lymph nodes (isolated small
raised lumps under the skin)
• chest pains and palpitations
These are serious side effects. You may
need urgent medical attention.

If any of the following happen, tell your
doctor as soon as possible:
• pain and inflammation at the injection
site (in rare instances severe tissue
damage has required amputation),
some discolouration and pain above the
injection site, known as “Purple Glove
syndrome” can occur
• tightness of the chest or wheezing
• dizziness/fainting/vertigo
• fever
• persistent pain, tingling or numbness
• contraction of the fingers (bending in to
the palm) (Dupuytren’s contracture)
• slurred speech
• muscle twitching and/or rapid
uncontrollable eye movements
• fits or seizures
• difficulties associated with muscular
movement: loss of muscle co-ordination,
clumsiness or unsteadiness, shaking and
loss of muscle tone
• bleeding, tender or enlarged gums (may
be reduced by maintaining good oral
hygiene and massaging the gums)

Instructions for use and handling
For single use. Discard any unused contents.
The product should be visually inspected for
particulate matter and discolouration prior to
Phenytoin Injection is suitable for use as long
as it remains free of haziness and precipitate.
A precipitate might form if the product has been
kept in a refrigerator or freezer. This precipitate will
dissolve if allowed to stand at room temperature.
The product will then be suitable for use.

joint pain
yellowing of the eyes and skin
enlargement of facial features including
thickening of the lips
unusual and excessive hair growth on
body and face
increased sweating
Peyronie’s disease (a condition where
male patients experience a deformation of
the penis which may cause pain when the
penis is erect)
unusual tiredness, drowsiness or
a feeling of nervousness
loss of appetite and weight
taste changes
* DRESS (Drug Reaction with Eosinophilia
and Systemic Symptoms) that appears
initially as flu-like symptoms and a rash
on the face and then an extended rash
with a high temperature, increased level
of liver enzymes seen in blood tests and
an increase in a type of white blood cell
(eosinophilia) and enlarged lymph nodes.
The consequences can be life-threatening.

There have been reports of bone disorders
including osteopenia and osteoporosis
(thinning of the bone) and fractures. Check
with your doctor or pharmacist if you are on
long-term antiepileptic medication, have a
history of osteoporosis, or take steroids.
Phenytoin may cause problems with
breathing, blood pressure, heart and liver
function, blood-sugar levels and blood cell
count. Your doctor may do tests to check for
these side effects.
Reporting of side effects
If you get any side effects, talk to your doctor.
This includes any possible side effects not
listed in this leaflet. You can also report side
effects directly via:
Yellow Card Scheme
By reporting side effects you can help provide
more information on the safety of this medicine.

Keep out of the reach and sight of children

This medicine must not be used after the
expiry date which is stated on the ampoule
and carton after 'EXP'. Where only a month
and year is stated, the expiry date refers to
the last day of that month.

The ampoules should be kept in the outer
carton, in order to protect from light, and
stored at, or below, 25°C.
Unused portions of opened ampoules must
not be stored for later use.

Visible signs of deterioration
Only clear, colourless solutions should
be used. Opaque, cloudy or discoloured
solutions should not be used.

What Phenytoin Injection contains
The active substance is phenytoin sodium.
Each millilitre (ml) of solution contains
50 milligrams (mg) of phenytoin sodium.
The other ingredients are ethanol, propylene
glycol and Water for Injections. See
section 2 ‘Important information about some of
the ingredients of Phenytoin Injection’ for further
information about ethanol and propylene glycol.

What Phenytoin Injection looks like and
contents of the pack
Phenytoin Injection is a clear, colourless
solution for injection which comes in glass
containers called ampoules.
It is supplied in packs containing
5 x 250 mg/5 ml ampoules.

Marketing authorisation holder and
Hospira UK Limited,
Horizon, Honey Lane, Hurley,
Maidenhead, SL6 6RJ, UK
This leaflet was last revised in August 2016.
For infusion administration, Phenytoin Injection
should be diluted in 50 - 100 ml of normal
saline, with the final concentration of phenytoin
in the solution not exceeding 10 mg/ml.
Administration should commence immediately
after the mixture has been prepared and must
be completed within one hour (the infusion
mixture should not be refrigerated). An in-line
filter (0.22 - 0.50 microns) should be used. The
diluted form is suitable for use as long as it
remains free of haziness and precipitate.

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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.