INTRODUCTION
phenytoin (fen-i-toyn)
Dilantin, Phenytek
Classification
Therapeutic: antiarrhythmics (group IB), anticonvulsants
Pharmacologic:
hydantoins
Indications
Treatment/prevention of tonic-clonic (grand mal) seizures and complex partial seizures. Unlabeled Use: As an antiarrhythmic, particularly for ventricular arrhythmias associated with digoxin toxicity, prolonged QT interval, and surgical repair of congenital heart
diseases in children. Management of neuropathic pain, including trigeminal neuralgia.
Action
Limits seizure propagation by altering ion transport. May also decrease synaptic transmission. Antiarrhythmic properties as a result of shortening the action potential and ↓ automaticity. Therapeutic
Effects: Diminished seizure activity. Termination of ventricular arrhythmias.
Adverse Reactions/Side Effects
Most listed are for chronic use of phenytoin
CNS: ataxia, agitation, confusion, dizziness, drowsiness, dysarthria, dyskinesia, extrapyramidal syndrome, headache, insomnia, weakness. EENT: diplopia, nystagmus. CV:
hypotension (↑ with IV phenytoin), tachycardia. GI: gingival hyperplasia, nausea, constipation, drug-induced hepatitis, vomiting. Derm: hypertrichosis,
rash, exfoliative dermatitis, pruritus. Hemat: AGRANULOCYTOSIS, APLASTIC ANEMIA, leukopenia, megaloblastic anemia, thrombocytopenia. MS: osteomalacia. Misc: ALLERGIC REACTIONS, INCLUDING STEVENS-JOHNSON SYNDROME, fever,
lymphadenopathy.
PHYSICAL THERAPY IMPLICATIONS
Examination and Evaluation
Be alert for phenytoin hypersensitivity syndrome (fever, skin rash, lymphadenopathy). Rash usually occurs within the first 2 wk of therapy. Hypersensitivity syndrome usually occurs at 3–8 wk
but may occur up to 12 wk after initiation of therapy. Report these signs immediately because this syndrome may lead to renal failure, rhabdomyolysis, or hepatic necrosis.
Monitor other skin reactions (itching/burning skin, hives, exfoliation, dermatitis). Notify physician immediately about because certain skin reactions may indicate serious hypersensitivity reactions (Stevens-Johnson syndrome).
Be alert for signs of agranulocytosis (fever, sore throat, mucosal
lesions, signs of infection), aplastic anemia (unusual fatigue, weakness, dizziness, pallor), thrombocytopenia (bruising, nose bleeds, bleeding gums), or fatigue and poor health that might be due to other anemias and blood dyscrasias. Report these signs to the physician immediately. Periodic blood tests may be needed to monitor WBC and RBC counts.
Document the number, duration, and severity of seizures to help determine if this drug is effective in reducing seizure activity.
Assess dizziness that might affect gait, balance, and other functional activities (See Appendix C). Report balance problems and functional limitations to the physician and nursing staff, and caution the patient and family/caregivers to guard against falls and trauma.
Monitor daytime drowsiness, confusion, or agitation. Repeated or excessive symptoms may require
change in dose or medication.
Assess gait and motor function and document any signs of incoordination, ataxia, or other motor symptoms that might indicate extrapyramidal syndrome such as involuntary movements of the jaw, limbs, Parkinson-like symptoms, and other dystonias and dyskinesias. Report these signs to the physician.
If treating neuropathic pain, use visual analogue scales and other appropriate pain scales to assess the patient's pain and help ...
(fen’i-toy-in)
Dilantin-125, Dilantin-30 Pediatric, Dilantin Infatab
PHENYTOIN SODIUM EXTENDED
Dilantin Kapseals
PHENYTOIN SODIUM PROMPT
Dilantin
Classifications: central nervous system agent; anticonvulsant; hydantoin
Pregnancy Category: D
NURSING IMPLICATIONS
Assessment & Drug Effects
- Continuously monitor vital signs and symptoms during IV infusion and for an hour afterward. Watch for respiratory depression. Constant observation
and a cardiac monitor are necessary with older adults or patients with cardiac disease. Margin between toxic and therapeutic IV doses is relatively small.
- Be aware of therapeutic serum concentration: 10–20 mcg/mL; toxic level: 30–50 mcg/mL; lethal level: 100 mcg/mL. Steady-state therapeutic levels are not achieved for at least 7–10 d.
- Lab tests: Periodic serum phenytoin concentration; CBC with differential, platelet count, and Hct and Hgb; serum glucose, serum calcium, and serum
magnesium; and liver funtion tests.
- Observe patient closely for neurologic adverse effects following IV administration. Have on hand oxygen, atropine, vasopressor, assisted ventilation, seizure precaution equipment (mouth gag, nonmetal airway, suction apparatus).
- Be aware that gingival hyperplasia appears most commonly in children and adolescents and never occurs in patients without teeth.
- Make sure patients on prolonged therapy have adequate intake of vitamin
D-containing foods and sufficient exposure to sunlight.
- Monitor diabetics for loss of glycemic control.
- Check periodically for decrease in serum calcium levels. Particularly susceptible: patients receiving other anticonvulsants concurrently, as well as those who are inactive, have limited exposure to sun, or whose dietary intake is inadequate.
- Observe for symptoms of folic acid deficiency: neuropathy, mental dysfunction.
- Be alert to symptoms of hypomagnesemia (see
Appendix F); neuromuscular symptoms: tetany, positive Chvostek’s and Trousseau’s signs, seizures, tremors, ataxia, vertigo, nystagmus, muscular fasciculations.
Patient & Family Education
- Be aware that drug may make urine pink or red to red-brown.
- Report symptoms of fatigue, dry skin, deepening voice when receiving long-term therapy because phenytoin can unmask a low thyroid reserve.
- Do not alter prescribed drug regimen. Stopping
drug abruptly may precipitate seizures and status epilepticus.
- Do not to request/accept change in drug brand when refilling prescription without consulting physician.
- Understand the effects of alcohol: Alcohol intake may increase phenytoin serum levels, leading to phenytoin toxicity.
- Discontinue drug immediately if a measles-like skin rash or jaundice appears and notify physician.
- Be aware that influenza vaccine during phenytoin treatment may increase seizure
activity. Understand that a change in dose may be necessary.
- Do not breast feed while taking this drug.
What Do You Think?
What should the nurse keep in mind when administering phenytoin IV?
Continually monitor patient's cardiac rhythm and check BP frequently and regularly during IV infusion. Suggest use of fosphenytoin sodium if IV route is needed. Monitor injection sites carefully; drug solutions are very alkaline and irritating. WARNING: Monitor for therapeutic serum levels of 10–20 mcg/mL.
What administration considerations apply to phenytoin?
Intramuscular administration is not recommended due to its erratic absorption and local reaction. The drug is slowly administered intravenously directly into a large central or peripheral vein through an IV catheter less than 20 gauge, not exceeding a rate of 50 mg/minute. It requires dilution with sodium chloride.
What precautions are necessary when administering phenytoin by intravenous infusion?
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.
What should the nurse monitor for with phenytoin?
Patients taking phenytoin will need regular and close monitoring of their serum phenytoin levels. Signs of phenytoin toxicity are neurological in nature: ataxia, confusion, slurred speech, nystagmus, nausea and confusion. Phenytoin is very toxic to the tissues, so avoid IV extravasation.