F Toin Inj
Phenytoin Sodium Injection USP
Description
Phenytoin Sodium Injection is available in 50mg/ml – 2ml Inj
Indication
Epilepsy
Status epilepticus
Neuropathic pain
Choreoathetosis
Myotonia
Arrhythmias where first line treatment not effective
Tetralogy of Fallot – post operative
Dosage
IV Dose for Seizures
Do not exceed the infusion rate of 50mg/min
Loading dose – 10 to 15mg/kg IV slowly
Maintenance dose – 100mg IV every 6 to 8 hours
IM Dose
Avoid the IM route due to erratic absorption
IV Dose for Arrhythmias
1.25 mg/kg IV every 5 minutes
IV Dose for status Epilepticus
Loading Dose – 15 to 20mg/kg by slow IV administration (at a rate not exceeding 50mg/minute)
Maintenance Dose – 100mg 6 to 8 hours
Uses
To treat
Convulsions (Control seizures)
Tonic – clonic (grandma seizures)
Psychomotor (Temporal lobe seizures)
Contraindications
Known hypersensitivity to hydantion products. Because of its effect on ventricular automaticity, IV phenytoin is contraindicated in sinus bradycardia, sinoatrial block, second and third degree AV block, patients with Adams strokes syndrome
Adverse Drug Reaction
Fatigue
Irritability
Headache
Nystagmus
Ataxia
Dyskinesia
Lethargy
Slurred Speech
Vertigo
Gum hypertrophy
Hirsutism
Osteomalacia
Coarse facies
Cognitive dysfinction
Folate deficiency
Drug Interaction
Amiodarone, Chloramphenicol, Cimetidine, Disulfiram, Erythromycin, Fluconazole, Fluoxetine, Isoniazid, Ketoconazole, Methylphenidate, Omeprazole, Phenylbutazone, Salicylates, Sulfonamides, Trazodone, Warfarin and Acute alcohol ingestion – Drugs may increase Phenytoin serum levels
Carbmazepine, Chronic Alcohol Abuse, Diazoxide, Rifampicin and Theophylline – Drugs may decrease phenytoin levels
Phenobarbital, Valporic acid and Sodium Valporate – Drugs may either increase or decrease Phenytoin serum levels
Corticosteroids, Diazoxide, Digitalis glycosides, Doxycycline, Estrogens, Furosemide, Levodopa, Methadone, Oral Contraceptives, Quinidine, Theophylline, Vitamin D and warfarin, Drug efficacy may impaired by Phenytoin
Mechanism of Action
Phenytoin is an anticonvulsant which elevates the seizure threshold in the motor cortex by limiting the post tetanic potentiation (PTP) of synaptic transmission. It exerts this effect by preventing the excessive accumulation of intracellular sodium during tetanic stimulation by either reducing the passive influx of sodium or increasing the efficiency of the sodium pump