Loading…
PHENYTOIN SODIUM is a brand name for Phenytoin. The medicine, its uses, side effects and dosage are the same regardless of brand.
Used for: Phenytoin Injection is indicated for the control of status epilepticus of the tonic-clonic (grand mal) type and prevention and treatment of seizures occurring during or following neurosurgery and/or severe head injury.
Verbatim from this product's MHRA label. Tap a section to expand.
e. serial epilepsy, intravenous diazepam or a short-acting barbiturate is recommended prior to administration of phenytoin because of the more rapid onset of action of the former. Following the use of diazepam in patients having continuous seizures and in the initial management of serial epilepsy a loading dose of phenytoin 10 - 15mg/kg should be injected slowly intravenously, at a rate not exceeding 50mg per minute in adults (this will require approximately 20 minutes in a 70kg patient).
The loading dose should be followed by maintenance doses of 100mg orally or intravenously every 6 to 8 hours. In neonates, it has been shown that absorption of phenytoin is unreliable after oral administration, but a loading dose of 15-20mg/kg of phenytoin intravenously will usually produce serum concentrations of 10–20 mg/l phenytoin which is within the generally accepted therapeutic range.
The drug should be injected slowly intravenously at a rate of 1-3mg/kg/min. Determination of phenytoin serum levels is advised during use in the management of status epilepticus and subsequently whilst establishing maintenance dosage.
The clinically effective range is usually 10- 20mg/1 although some cases of tonic-clonic seizures may be controlled with lower serum levels of phenytoin. Intramuscular administration should not be used in the treatment of status epilepticus because peak plasma levels may not be reached for up to 24 hours.
Other clinical conditions:
It is not possible to provide a universally applicable dosage schedule. The intravenous route of administration is preferred. Dosage and dosing interval will be determined by the needs of the individual patient and factors such as previous anti- epileptic therapy, seizure control, age and general medical condition must be considered.
m. injection, such use may be appropriate in certain conditions. When short-term intramuscular administration is necessary for a patient previously stabilised orally, compensating dosage adjustments are essential to maintain therapeutic serum levels.
An intramuscular dose 50% greater than the oral dose is necessary to maintain these levels. When returned to oral administration, the dose should be reduced by 50% of the original oral dose, for the same period of time the patient received phenytoin intramuscularly.
In the table below all adverse reactions with phenytoin are listed by class and frequency: Rare (≥1/10,000 to <1/1,000), not known (cannot be estimated from the available data). Signs of toxicity are associated with cardiovascular and central nervous system depression.
MedDRA System organ Class Frequency Undesirable Effects Blood and lymphatic system disorders Not Known Pure red cell aplasia, Haematopoietic complications , some fatal, have occasionally been reported in association with administration of phenytoin.
These have included thrombocytopenia, leucopenia, granulocytopenia, agranulocytosis, and pancytopenia with or without bone marrow suppression and aplastic anaemia. While macrocytosis and megaloblastic anaemia have occurred, these conditions usually respond to folic acid therapy.
There have been a number of reports suggesting a relationship between phenytoin and the development of lymphadenopathy (local or generalised) including benign lymph node hyperplasia, pseudolymphoma, lymphoma, and Hodgkin's disease.
Although a cause and effect relationship has not been established, the occurrence of lymphadenopathy indicates the need to differentiate such a condition from other types of lymph node pathology. g. fever, rash and liver involvement.
In all cases of lymphadenopathy, follow- up observation for an extended period is indicated and every effort should be made to achieve seizure control using alternative antiepileptic drugs. Immune system disorders Rare Not Known Hypersensitivity syndrome Anaphylactoid reaction, anaphylactic reaction, periarteritis nodosa, immunoglobulin abnormalities may occur.
Psychiatric disorders Not Known Insomnia, transient nervousness, confusion. Nervous system disorders Rare Not Known There have also been rare reports of phenytoin- induced dyskinesia, including chorea, dystonia, tremor, and asterixis, similar to those induced by phenothiazine and other neuroleptic drugs.
General In adults, intravenous administration should not exceed a rate of 50mg per minute. In neonates, phenytoin should be administered at a rate of 1 - 3mg/kg/min. Hypotension usually occurs with rapid administration of phenytoin by the intravenous route.
Irritation and inflammation of soft tissue has occurred at the injection site with and without extravasation of intravenous phenytoin. Soft tissue irritation may vary from slight tenderness to extensive necrosis, sloughing and in rare instances has led to amputation.
Subcutaneous or perivascular injection should be avoided because of the highly alkaline nature of the solution. The intramuscular route is not recommended for the treatment of status epilepticus because of slow absorption. Serum levels of phenytoin in the therapeutic range cannot be rapidly achieved by this method.
Intravenous phenytoin should be used with caution in patients with hypotension and severe myocardial insufficiency. Antiepileptic drugs should not be abruptly discontinued because of the possibility of increased seizure frequency, including status epilepticus.
When, in the judgement of the clinician, the need for dosage reduction, discontinuation, or substitution of alternative antiepileptic medication arises, this should be done gradually. However, in the event of an allergic or hypersensitivity reaction, rapid substitution of alternative therapy may be necessary.
In this case, alternative therapy should be an antiepileptic drug not belonging to the hydantoin chemical class. Acute alcoholic intake may increase phenytoin serum levels while chronic alcoholic use may decrease serum levels. Phenytoin may precipitate or aggravate absence seizures and myoclonic seizures.
Because phenytoin is highly protein bound and extensively metabolised by the liver, reduced maintenance dosage may be required in patients with impaired liver function to prevent accumulation and toxicity. Where protein binding is reduced, as in uraemia, total serum phenytoin levels will be reduced accordingly.
1. Because of its effect on ventricular automaticity, it is also contra-indicated in sinus bradycardia, sino-atrial block, and second and third degree A-V block, and patients with Adams-Stokes syndrome. Intra-arterial injection must be avoided because of the high pH of the solution.
Co-administration of phenytoin is contraindicated with delavirdine due to the potential for loss of virologic response and possible resistance to delavirdine or to the class of non-nucleoside reverse transcriptase inhibitors.
Not medical advice. Always read the patient information leaflet and follow your prescriber or pharmacist.
Other brands of Phenytoin in United Kingdom.
Know a brand we are missing in United Kingdom? Suggest a brand →
Brand names are compiled from public regulatory records for active-ingredient mapping only. Drugvu is not affiliated with any manufacturer. This is not medical advice.
This is to prevent excessive serum levels due to continued release from intramuscular tissue sites Neurosurgery: In a patient who has not previously received the drug, Phenytoin Injection 100 - 200mg (2 - 4ml) may be given intramuscularly at approximately 4- hour intervals prophylactically during neurosurgery and continued during the postoperative period for 48 - 72 hours.
The dosage should then be reduced to a maintenance dose of 300mg and adjusted according to serum level estimations. If possible, intramuscular injections of phenytoin should not be continued for more than one week; after this, alternative routes such as naso-gastric intubation should be considered.
For time periods less than one week, the patient switched from intramuscular administration should receive half the original oral dose for the same period of time the patient received phenytoin intramuscularly. Measurement of serum levels is of value as a guide to an appropriate adjustment of dosage.
2). It should be noted that complications may occur more readily in elderly patients.
Paediatric population Neonates:
In neonates it has been shown that absorption of phenytoin is unreliable after oral administration, but a loading dose of phenytoin injected slowly intravenously at a rate of 1-3mg/kg/min at a dose of 15-20mg/kg will usually produce serum concentrations of phenytoin within the generally accepted therapeutic range of 10-20mg/l.
Infants and children:. Children tend to metabolize phenytoin more rapidly than adults. This should be considered when determining dosage regimens; monitoring serum levels is therefore particularly beneficial in such cases.
Method of administration:
Intravenous. Intramuscular. Solutions for parenteral administration should be inspected visually for particulate matter and discoloration prior to use. Only a clear solution should be used and the product should be discarded if a precipitate or haziness develops in the solution.
On refrigeration or freezing, a precipitate might form, but this will dissolve when the solution is allowed to stand at room temperature. The product is still suitable for use. Only a clear solution should be used. A faint yellow discoloration may develop, but this does not affect the potency of the solution.
There is a relatively small margin between full therapeutic effect and minimally toxic doses of this drug. Optimum control without clinical signs of toxicity can most often be achieved with serum levels in the range 10 - 20mg/1 (40 - 80 micromoles/1).
Because of the risk of local toxicity, intravenous phenytoin should be injected slowly directly into a large vein through a large-gauge needle or intravenous catheter. Each injection or infusion of intravenous phenytoin should be preceded and followed by an injection of sterile saline through the same needle or catheter to avoid local venous irritation due to alkalinity of the solution.
4) For administration by intravenous infusion phenytoin injection should be diluted in 50 - 100 ml of normal saline, and the final concentration of phenytoin in the solution should not exceed 10 mg/ml, the infusion mixture should not be refrigerated.
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 […]
Adverse reactions in this body system are common and are usually dose-related. Reactions include nystagmus, ataxia, dysarthria and decreased coordination. 4). Dizziness, motor twitchings, headache, paraesthesia, somnolence, drowsiness and dysgeusia have also been observed.
A predominantly sensory peripheral polyneuropathy has been observed in patients receiving long-term phenytoin therapy. Tonic convulsions have also been reported. Peripheral sensory neuropathy. Ear and labyrinth disorders Not Known Vertigo Cardiac disorders Not Known Hypotension may occur.
Arrhythmias including bradycardia, atrial and ventricular depression and ventricular fibrillation can occur and these have, in some cases, resulted in asystole/ cardiac arrest and death. Severe complications are most commonly encountered in older people or gravely ill patients.
Respiratory, thoracic and mediastinal disorders Not Known Pneumonitis, alterations in respiratory function including respiratory arrest may occur. Gastrointestinal disorders Not Known Vomiting, nausea, gingival hyperplasia, constipation.
4) has been reported and may in rare cases be fatal (the syndrome may include, but is not limited to, symptoms such as arthralgia, eosinophilia, pyrexia, hepatic function abnormal, lymphadenopathy or rash). Several individual case reports have suggested that there may be an increased, although still rare, incidence of hypersensitivity reactions, including skin rash and hepatotoxicity, in black patients.
Dermatological manifestations sometimes accompanied by fever have included scarlatiniform or morbilliform rashes. A morbilliform rash (measles like) is the most common. Other types of dermatitis are seen more rarely. 4). Skin exfoliation.
Musculoskeletal and connective tissue disorders Not Known Systemic lupus erythematosus, arthropathy. There have been reports of decreased bone mineral density, osteopenia, osteoporosis and fractures in patients on long-term therapy with phenytoin.
The mechanism by which phenytoin affects bone metabolism has not been identified. 4). Dupuytren’s contracture. Arthralgia. Renal and urinary disorders Not Known Tubulointerstitial nephritis, Peyronie’s Disease. General disorders and administration site conditions Not Known Local irritation, inflammation, tenderness, necrosis and oedema have been reported with or without extravasation of intravenous phenytoin.
Fever. Investigations Not Known Thyroid function test abnormal Paediatric population The adverse event profile of phenytoin is generally similar between children and adults. Gingival hyperplasia occurs more frequently in paediatric patients and in patients with poor oral hygiene.
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. uk/yellowcard or search for MHRA […]
However, as the pharmacologically active free drug concentration is unlikely to be altered, under these circumstances therapeutic control may be achieved with total phenytoin levels below the normal range 10 - 20mg/l. Dosage should not exceed the minimum necessary to control convulsions.
Due to an increased fraction of unbound phenytoin in patients with renal or hepatic disease, or in those with hypoalbuminemia, the interpretation of total plasma phenytoin concentrations should be made with caution. Unbound concentration of phenytoin may be elevated in patients with hyperbilirubinemia.
Unbound phenytoin concentrations may be more useful in these patient populations. Cardiovascular Effect The most significant signs of toxicity with the intravenous use of phenytoin are cardiovascular collapse and/or central nervous system depression.
Severe cardiotoxic reactions and fatalities due to depression of atrial and ventricular conduction and ventricular fibrillation, respiratory arrest and tonic seizures have been reported, particularly in elderly or gravely ill patients, if the preparation is given too rapidly or in excess.
Anticonvulsant Hypersensitivity Syndrome/ Drug Reaction with Eosinophilia and Systemic Symptoms (AHS/DRESS): Anticonvulsant Hypersensitivity Syndrome (AHS) is a rare drug-induced, multiorgan syndrome that is potentially fatal and occurs in some patients taking anticonvulsant medication, including phenytoin.
AHS/DRESS typically, although not exclusively is characterized by fever, rash, lymphadenopathy, and other multiorgan pathologies, such as hepatitis, nephritis, haematological abnormalities, myocarditis, myositis or pneumonitis. Initial symptoms may resemble an acute viral infection.
Other common manifestations include arthralgias, jaundice, hepatomegaly, leucocytosis, and eosinophilia. The mechanism is unknown. The interval between first drug exposure and symptoms is usually 2-4 weeks, but has been reported in individuals receiving anticonvulsants for 3 or more months.
If such signs and symptoms occur, the patient should be evaluated immediately. Phenytoin should be discontinued if an alternative aetiology for the signs and symptoms cannot be established. Drug rash with eosinophilia and systemic symptoms (DRESS) reflects a serious hypersensitivity reaction to drugs, characterized by skin rash, fever, lymph node enlargement, and internal organ involvement.
Cases of DRESS have been noted in patients taking phenytoin. Patients at higher risk for developing AHS/DRESS include black patients, patients who have a family history of or who have experienced this syndrome in the past (with phenytoin or other anticonvulsant drugs), and immuno-suppressed patients.
The syndrome is more severe in previously sensitized individuals. If a patient is diagnosed with AHS, discontinue the phenytoin and provide appropriate supportive measures.
Serious skin reactions:
Life-threatening cutaneous reactions Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) have been reported with the use of Phenytoin. Patients should be advised of the signs and symptoms and monitored closely for skin reactions.
The highest risk for occurrence of SJS and TEN is within the first weeks of treatment. g. progressive skin rash often with blisters or mucosal lesions) are present, Phenytoin sodium treatment should be discontinued. The best results in managing SJS and TEN come from early diagnosis and immediate discontinuation of any suspect drug.
Early withdrawal is associated with a better prognosis. If the patient has developed SJS or TEN with the use of Phenytoin and it must not be re-started in this patient at any time. The physician should advise the patient to discontinue treatment if the rash appears.
If the rash is of a milder type (measles-like or scarlatiniform), therapy may be resumed after the rash has completely disappeared. If the rash recurs upon […]