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Phenytoin Sodium 50mg/ml Solution for Injection
Phenytoin Sodium 50mg/ml Solution for Injection
The name of your medicine is Phenytoin Sodium 50mg/ml Solution for Injection. It will be referred to as Phenytoin Injection for ease hereafter.
1. What Phenytoin Injection is and what it is used for
2. What you need to know before you are given Phenytoin Injection
3. How Phenytoin Injection is given to you
4. Possible side effects
5. How to store Phenytoin Injection
6. Contents of the pack and other information
Phenytoin belongs to a group of drugs known as hydantoins. It is called an anticonvulsant because it works by controlling the overactivity in the brain that can cause epilepsy or seizures (fits).
Phenytoin Injection is used to:
You should consult your doctor if you are unsure why you have been given Phenytoin Injection if you do not feel better or if you feel worse.
Make sure your doctor knows if you suffer from any of the above before you are given the injection.
Talk to your doctor or nurse before you are given Phenytoin Injection if you suffer from or have suffered in the past from any of the following conditions:
The risk of these serious skin side effects may be associated with a variant in genes in a subject with Chinese or Thai origin. If you are of such origin and have been tested previously carrying this genetic variant (HLA-B* 1502), discuss this with your doctor before using Phenytoin Injection.
Black patients may be at greater risk of liver problems, serious skin reactions and allergic reactions. If you are taking phenytoin at the same time as you receive radiation therapy to your head and the dose of another medication called corticosteroids is reduced, you may more likely to develop a severe skin rash called erythema multiform or one that causes blistering called Stevens Johnson Syndrome or Toxic Epidermal Necrosis (see Possible Side Effects in section 4).
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. Tell your doctor if any of these apply to you as special care may be needed. Your doctor will take particular care with this medicine if you are elderly or gravely ill.
Phenytoin may precipitate or aggravate absence seizures and myoclonic seizures (two specific types of epilepsy).
There is a risk of harm to the unborn child if Phenytoin Injection is used during pregnancy. Women of childbearing age should use effective contraception during treatment with Phenytoin Injection (see Pregnancy and breast-feeding).
Tell your doctor if you are taking, have recently taken or might take any other medicines.
This will allow your doctor to decide whether it is safe for you to be given phenytoin.
Some medicines can affect the way Phenytoin Injection works, or Phenytoin Injection itself can reduce the effectiveness of other medicines taken at the same time. These include:
Speak to your doctor before being given this medicine if you have recently had a drink of alcohol.
Drinking a lot of alcohol can also affect the concentration of Phenytoin in your blood.
What you should know about the use of antiepileptic drugs in pregnancy
If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor for advice before taking this medicine.
If you are planning to become pregnant you should discuss your epilepsy treatment with your doctor as early as possible before you become pregnant. If you do get pregnant or think you may be pregnant while you are taking Phenytoin Injection, you must tell your doctor straight away and discuss possible risks the epilepsy medicine you are taking might pose to your unborn baby. You should not stop your treatment without discussing this with your doctor. Suddenly stopping may lead to breakthrough seizures which may harm you and your unborn baby. It is important that your epilepsy remains well controlled, but, as with other anti-epilepsy treatments, there is a risk of harm to the foetus.
Taking phenytoin during pregnancy increases the chance that the baby may have a physical birth abnormality.
Studies with women treated with phenytoin for epilepsy during pregnancy have shown that around babies in every 100 will have serious physical birth abnormalities. This compares to 2-3 babies in every 100 born to women who don’t have epilepsy.
The most common types of serious physical birth abnormalities (major congenital malformations) reported for phenytoin include abnormalities of the lip and palate, heart, skull, nail and finger disorders and growth abnormalities.
Taking more than one epilepsy medicine at the same time may also increase the risk of physical birth abnormalities. Where possible, your doctor will consider using one epilepsy medicine only to control your epilepsy.
Your doctor may advise you to take folic acid if you’re planning to become pregnant and while you’re pregnant. Your doctor may adjust your epilepsy medicine when you take folic acid.
Some studies observed that taking phenytoin during pregnancy increases the chance that the baby may have problems affecting learning and thinking abilities.
Make sure you are very clear about the risks and benefits of taking Phenytoin Injection.
Do not stop taking Phenytoin Injection until you have seen your doctor as it is important to control your fits. If given during pregnancy phenytoin may affect the baby but your doctor may decide that it is very important that you continue with phenytoin. He or she will explain the risks to you.
Phenytoin Injection can cause major birth defects. If you take Phenytoin Injection during pregnancy your baby has up to 3 times the risk of having a birth defect than women not taking an antiepileptic medication. Major birth defects including growth, skull, facial, nail, finger and heart abnormalities have been reported. Some of these may occur together as part of a fetal hydantoin syndrome.
Problems with neurodevelopment (development of the brain) have been reported in babies born to mothers who used phenytoin during pregnancy. Some studies have shown that phenytoin negatively affects neurodevelopment of children exposed to phenytoin in the womb, while other studies have not found such an effect. The possibility of an effect on neurodevelopment cannot be ruled out.
As phenytoin is released into breast milk, you should not breast-feed if you are being given this medicine.
Phenytoin Injection may cause dizziness or drowsiness. If you experience these symptoms, do not drive or use any tools or machinery.
Ask your doctor for advice before taking any medicine.
This medicine contains less than 1 mmol sodium (23 mg) per 5 ml, that is to say essentially ‘sodium-free’.
Phenytoin Injection is given by a doctor or nurse. It may be given as an injection slowly into a muscle or a large vein. Alternatively, it may be diluted and given as a drip or infusion into one of your large veins (intravenously). When given as an intravenous infusion, Phenytoin Injection must be diluted with normal saline. Intramuscular or intravenous Phenytoin Injection should not be added to dextrose or dextrose-containing solutions as this could interfere with the dose of this medicine.
The correct dose will be calculated by your doctor according to your body weight and will be written as the equivalent dose of phenytoin sodium (PE). The dose will be as mg per dose if given as an injection or mg per ml of solution if given as an infusion (drip). A repeat injection may be given after 30 minutes if necessary.
During your treatment your doctor may monitor your blood levels of phenytoin by taking regular blood samples. Sometimes it is necessary to give Phenytoin Injection into your muscle if you cannot continue to take it by mouth. This is not normally continued for longer than one week. When switching from oral Phenytoin to intramuscular injection, the dose needs to be increased by approximately 50%. When switching back to oral Phenytoin, the dose should be reduced to half the original oral dose for the same period of time that the intramuscular injection was given. This is because phenytoin continues to be released from your muscles for some time after the injections have been given.
The recommended dose is as follows:
Severe epileptic seizure or fits (Status Epilepticus)
A dose of 10 to 15 mg per kg of body weight is given intravenously at a rate not exceeding 50 mg per minute in adults. This is followed by more Phenytoin Injection given every 6 to 8 hours either by injection or by mouth.
If Phenytoin Injection does not stop your seizures, other treatments will be tried.
A dose of 100 to 200 mg may be given into your muscle (intramuscularly) approximately every 4 hours during surgery and for two to three days afterwards to prevent seizures. This dosage may then be reduced to a maintenance dose of 300 mg daily and adjusted according to your blood levels.
Lower or less frequent dosing may be needed in some elderly patients due to decreased clearance of Phenytoin Injection. Your doctor may not need to change your dose, but side effects can occur more often in the elderly.
Make sure your doctor knows if you have liver or kidney problems as you may need your dose adjusted.
No dosage adjustment is required, but children tend to breakdown the medicine faster than adults and this may mean that your doctor has to change the number or timing of the Phenytoin Injection doses.
The starting dose is usually 15 to 20 mg per kg of baby weight. Intravenous Phenytoin Injection should not be given to neonates at a rate faster than 1 to 3 mg per kg body weight per minute. Intravenous Phenytoin Injection is more reliably absorbed than oral Phenytoin in very young babies.
Tell your doctor immediately.
Phenytoin Injection is dangerous in overdose. The initial signs are nystagmus (condition of involuntary eye movement), diplopia (double vision), ataxia (the loss of full control of bodily movements) and dysarthria (motor speech disorder). Other signs are tremor, hyperflexia (muscle spasms), lethargy, nausea, vomiting. The patient may become comatose and hypotensive. Death is due to respiratory and circulatory depression.
If you think that you may have missed a dose, tell your doctor immediately.
If you have any further questions on the use of this medicine, ask your doctor or nurse.
Like all medicines, this medicine can cause side-effects, although not everybody gets them.
Rare: may affect up to 1 in 1,000 people:
Not known: frequency cannot be estimated from the available data
Please see your doctor if you notice any of these side effects and they cause you concern, or if you notice any side effects not listed in this leaflet.
If you get any side effects, talk to your doctor or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly 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. By reporting side effects you can help provide more information on the safety of this medicine.
Keep this medicine out of the sight and reach of children.
Do not use this medicine after the expiry date which is stated on the ampoule (a small bottle) label and carton, after ‘EXP’. The expiry date refers to the last day of that month.
Do not store above 30°C. Keep the ampoule in the outer carton in order to protect from light.
If only part of the contents of an ampoule is used, the remaining solution should be discarded.
Do not use this medicine if you notice a haziness or precipitate.
The solution should not be mixed with any other drugs.
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.
Phenytoin Injection is a clear, colourless, particle-free solution. Each carton contains ten 5ml ampoules of Phenytoin Injection.
This leaflet was last revised in January 2024.