Parenteral phenytoin is indicated for the control
of status epilepticus of the grand mal type, and prevention and treatment
of seizures occurring during neurosurgery.
-- A prolonged seizure or seizures repeated frequently enough to prevent recovery between episodes occurring over a period of 20-30 minutes. The most common subtype is generalized tonic-clonic status epilepticus, a potentially fatal condition associated with neuronal injury and respiratory and metabolic dysfunction. Nonconvulsive forms include petit mal status and complex partial status, which may manifest as behavioral disturbances. Simple partial status epilepticus consists of persistent motor, sensory, or autonomic seizures that do not impair cognition (see also EPILEPSIA PARTIALIS CONTINUA). Subclinical status epilepticus generally refers to seizures occurring in an unresponsive or comatose individual in the absence of overt signs of seizure activity. (From N Engl J Med 1998 Apr 2;338(14):970-6; Neurologia 1997 Dec;12 Suppl 6:25-30)
Tonic - clonic seizures
-- A generalized tonic-clinic seizure, characterized by loss of consciousness. This type of seizure may be preceded by an aura and is frequently followed by a period of confusion and lethargy (post-ictal state).
SPONDYLOMETAEPIPHYSEAL DYSPLASIA, SHORT LIMB-HAND TYPE
-- A generalized seizure disorder characterized by recurrent major motor seizures. The initial brief tonic phase is marked by trunk flexion followed by diffuse extension of the trunk and extremities. The clonic phase features rhythmic flexor contractions of the trunk and limbs, pupillary dilation, elevations of blood pressure and pulse, urinary incontinence, and tongue biting. This is followed by a profound state of depressed consciousness (post-ictal state) which gradually improves over minutes to hours. The disorder may be cryptogenic, familial, or symptomatic (caused by an identified disease process). (From Adams et al., Principles of Neurology, 6th ed, p329)
Phenytoin is contraindicated in patients with a history
of hypersensitivity to hydantoin products.Because
of its effect on ventricular automaticity, phenytoin is contraindicated
in sinus bradycardia, sino-atrial block, second and third degree A-V
block, and patients with Adams-Stokes syndrome.
-- Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.
-- A heart rate of less than 60 beats per minute, with its origin in the sinus node. (NCI)
-- A condition of fainting spells caused by heart block, often an atrioventricular block, that leads to BRADYCARDIA and drop in CARDIAC OUTPUT. When the cardiac output becomes too low, the patient faints (SYNCOPE). In some cases, the syncope attacks are transient and in others cases repetitive and persistent.
Intravenous administration should not exceed 50 mg
per minute in adults.In neonates, the drug
should be administered at a rate not exceeding 1 mg/kg/min to 3 mg/kg/min.Severe cardiotoxic reactions and fatalities have been
reported with atrial and ventricular conduction depression and ventricular
Severe complications are most commonly encountered in
elderly or gravely ill patients.Phenytoin should
be used with caution in patients with hypotension and severe myocardial
insufficiency.Hypotension usually occurs when
the drug is administered rapidly by the intravenous route.The intramuscular route is not recommended for the treatment
of status epilepticus since blood levels of phenytoin in the therapeutic
range cannot be readily achieved with doses and methods of administration
ordinarily employed.There have been a number
of reports suggesting a relationship between phenytoin and the development
of lymphadenopathy (local or generalized) 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.
involvement may occur with or without symptoms and signs resembling
serum sickness e.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.Acute alcoholic intake may increase phenytoin serum levels
while chronic alcoholic use may decrease serum levels.
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