ADVERSE REACTIONS
The most notable signs of toxicity associated with the intravenous use of this drug are cardiovascular collapse and/or central nervous system depression. Hypotension does occur when the drug is administered rapidly by the intravenous route. The rate of administration is very important; it should not exceed 50 mg per minute in adults, and 1 mg/kg/min to 3 mg/kg/min in neonates. At this rate, toxicity should be minimized.
Cardiovascular
Severe cardiotoxic reactions and fatalities have been reported with atrial and ventricular conduction depression and ventricular fibrillation. Severe complications are most commonly encountered in elderly or gravely ill patients.
Central Nervous System
The most common manifestations encountered with phenytoin therapy are referable to this system and are usually dose-related. These include nystagmus, ataxia, slurred speech, decreased coordination and mental confusion. Dizziness, insomnia, transient nervousness, motor twitchings, and headaches have also been observed. There have also been rare reports of phenytoin induced dyskinesias, including chorea, dystonia, tremor and asterixis, similar to those induced by phenothiazine and other neuroleptic drugs.
A predominantly sensory peripheral polyneuropathy has been observed in patients receiving long-term phenytoin therapy.
Gastrointestinal System
Nausea, vomiting, and constipation.
Integumentary System
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. Other more serious forms which may be fatal have included bullous, exfoliative or purpuric dermatitis, lupus erythematosus, Stevens-Johnson syndrome, and toxic epidermal necrolysis (see PRECAUTIONS).
Hemopoietic System
Hemopoietic complications, some fatal, have occasionally been reported in association with administration of phenytoin. These have included thrombocytopenia, leukopenia, granulocytopenia, agranulocytosis, and pancytopenia with or without bone marrow suppression. While macrocytosis and megaloblastic anemia have occurred, these conditions usually respond to folic acid therapy. Lymphadenopathy including benign lymph node hyperplasia, pseudolymphoma, lymphoma, and Hodgkin’s disease have been reported (see WARNINGS).
Connective Tissue System
Coarsening of the facial features, enlargement of the lips, gingival hyperplasia, hypertrichosis, and Peyronie’s disease.
Injection Site
Local irritation, inflammation, tenderness, necrosis, and sloughing have been reported with or without extravasation of intravenous phenytoin.
Other
Systemic lupus erythematosus, periarteritis nodosa, toxic hepatitis, liver damage, and immunoglobulin abnormalities may occur.
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REPORTS OF SUSPECTED PHENYTOIN SIDE EFFECTS / ADVERSE REACTIONS
Below is a sample of reports where side effects / adverse reactions may be related to Phenytoin. The information is not vetted and should not be considered as verified clinical evidence.
Possible Phenytoin side effects / adverse reactions in 51 year old female
Reported by a health professional (non-physician/pharmacist) from Singapore on 2011-10-05
Patient: 51 year old female
Reactions: Rash, Dermatitis Exfoliative
Suspect drug(s):
Phenytoin
Dosage: unk
Start date: 2011-08-04
End date: 2011-08-20
Ciprofloxacin HCL
Dosage: unk
Start date: 2011-08-16
End date: 2011-08-18
Gentamicin
Dosage: unk
Start date: 2011-08-18
End date: 2011-08-20
Possible Phenytoin side effects / adverse reactions in 31 year old male
Reported by a pharmacist from United States on 2011-10-06
Patient: 31 year old male weighing 75.2 kg (165.4 pounds)
Reactions: Weight Decreased, Gingival Hypertrophy, Toxicity TO Various Agents
Adverse event resulted in: hospitalization
Suspect drug(s):
Phenytoin
Possible Phenytoin side effects / adverse reactions in 51 year old female
Reported by a health professional (non-physician/pharmacist) from Japan on 2011-10-06
Patient: 51 year old female
Reactions: Drug Eruption, Hypersensitivity, Metastases TO Meninges, Inappropriate Antidiuretic Hormone Secretion
Adverse event resulted in: death
Suspect drug(s):
Phenytoin
Indication: Ovarian Cancer Metastatic
Paclitaxel
Dosage: 3 courses at 3 week interval. 160 mg/m2) weekly for a total of 20 courses,
Indication: Ovarian Cancer Metastatic
Cisplatin
Indication: Ovarian Cancer Metastatic
Carboplatin
Dosage: auc - 5
Indication: Ovarian Cancer Metastatic
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