Names and pronunciation
(foss-fen′i-toy-in) Cerebyx, Sequient
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Drug reference
(foss-fen′i-toy-in) Cerebyx, Sequient
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Func. class.: Anticonvulsant
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Chem. class.: Hydantoin, phosphate phenytoin ester
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ACTION: Inhibits spread of seizure activity in motor cortex by altering ion transport; increases AV conduction, pro- drug of phenytoin
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USES: Generalized tonic-clonic sei- zures, status epilepticus, partial seizures
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CONTRAINDICATIONS: Preg- nancy, hypersensitivity, bradycardia, SA and AV block, Stokes-Adams syndrome Precautions: Breastfeeding, allergies, renal/hepatic disease, myocardial insuffi- ciency, hypoalbuminemia, hypothyroid- ism, Asian patients positive for HLA-B 1502, abrupt discontinuation, agranulocy- tosis, alcoholism, carBAMazepine/barbi- turate hypersensitivity, bone marrow sup- pression, CAD, geriatric patients, hemolytic anemia, hyponatremia, methe- moglobinemia, myasthenia gravis, psycho- sis, suicidal ideation
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Black Box Warning: Dysrhythmias, hy- potension (rapid IV infusion) Black Box Warning: Because of the risk of hypotension, do not exceed rec- ommended infusion rates; continuous monitoring of ECG, B/P, and respira- tory function is recommended, especially throughout the period in which phenytoin concentrations peak (about 10-20 min after the end of the infusion) • Loading doses should always be followed by maintenance doses of oral or parenteral F phenytoin or parenteral fosphenytoin Black Box Warning: Adult: IV Infuse at a max rate of 150 mg PE/min; Elderly or debilitated adults: IV Infuse at a max 3 mg PE/kg/min or 150 mg PE/min, which- ever is less; Child: IV Infuse at a rate of 0.5-3 mg PE/kg/min or max 150 mg PE/ min, whichever is less; Infant/neonate: IV Infuse at a rate max 0.5-3 mg PE/kg/min Y-site compatibilities: Aminocaproic acid, amphotericin B lipid complex, amphoteri- cin B liposome, anidulafungin, atenolol, bivalirudin, bleomycin, CARBOplatin, CIS- platin, cyclophosphamide, cytarabine, DACTINomycin, DAPTOmycin, dexmedeto- midine, diltiazem, DOCEtaxel, doxacurium, eptifibatide, ertapenem, etoposide, fludara- bine, fluorouracil, gatifloxacin, gem- citabine, gemtuzumab, granisetron, ifosfamide, levofloxacin, linezolid, LORaze- pam, mechlorethamine, meperidine, meth- otrexate, metroNIDAZOLE, nesiritide, octreotide, oxaliplatin, oxytocin, PACLitaxel, palonosetron, pamidronate, pantoprazole, PEMEtrexed, PHENobarbital, piperacillin- tazobactam, rocuronium, sodium acetate, tacrolimus, teniposide, thiotepa, tigecy- cline, tirofiban, vinCRIStine, vinorelbine, voriconazole, zoledronic acid Black Box Warning: Rapid IV infu- sion: risk of hypotension and dysrhyth- mias with rapid infusion rates • Seizure activity, including type, location, duration, character; provide seizure pre- cautions • Drug level: target level 10-20 mcg/mL, toxic level 30-50 mcg/mL, wait >2 hr af- ter dose before testing, 4 hr after IM dose; phenytoin blood levels are used for this product • Blood studies: CBC, platelets q2wk until stabilized, then monthly × 12 mo, then q3mo; serum calcium, albumin, phosphorus, potassium • Mental status: mood, sensorium, affect, memory (long, short), suicidal thoughts/behaviors • Serious skin reactions: usually occur- ring within 28 days of treatment; if a rash develops, patient should be evaluated for DRESS • Pregnancy, breastfeeding: do not use in pregnancy; birth defects have occurred; avoid breastfeeding • Renal studies: urinalysis, BUN, urine creatinine • Hepatic studies: ALT, AST, bilirubin, creatinine • Allergic reaction: red, raised rash; product should be discontinued • Toxicity/bone marrow depression: nausea, vomiting, ataxia, diplopia, cardio- vascular collapse, slurred speech, confusion • Respiratory depression: rate, depth, character of respirations • Blood dyscrasias: fever, sore throat, bruising, rash, jaundice • Continuous monitoring of ECG, B/P, respiratory function • Rash: discontinue as soon as rash de- velops; serious adverse reactions such as Stevens-Johnson syndrome can occur
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SIDE EFFECTS CNS: Drowsiness, dizziness, insomnia, paresthesias, depression, suicidal ten- dencies, aggression, headache, confu- sion, paresthesia, emotional lability, syn- cope, cerebral edema CV: Hypo/hypertension, HF, shock, dysrhythmias EENT: Nystagmus, diplopia, blurred vision GI: Nausea, vomiting, diarrhea, constipa- tion, anorexia, weight loss, hepatitis, jaundice, gingival hyperplasia HEMA: Agranulocytosis, leukopenia, aplastic anemia, thrombocytopenia, meg- aloblastic anemia INTEG: Rash, lupus erythematosus, Ste- syndrome, hirsutism, vens-Johnson hypersensitivity, pruritus RESP: Bronchospasm, cough SYST: Hyperglycemia, hypokalemia, SJS/TEN in Asian patients positive for HLA-B 1502; drug reaction with eosino- philia and systemic symptoms (DRESS), purple glove syndrome, anaphylaxis
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INTERACTIONS Increase: fosphenytoin level—cimetidine, amiodarone, chloramphenicol, estro- gens, H2 antagonists, phenothiazines, sa- licylates, sulfonamides, tricyclics, CYP1A2 inhibitors Decrease: fosphenytoin effects—alcohol (chronic use), antihistamines, antacids, traMADol, antineoplastics, rifampin, folic acid, carBAMazepine, theophylline, CYP1A2 inducers Decrease: virologic response, resistance— delavirdine; do not use concurrently Drug/Herb Increase: anticonvulsant effect—ginkgo Decrease: anticonvulsant effect—gin- seng, valerian Drug/Lab Test Increase: glucose, alk phos Decrease: dexamethasone, metyrapone test serum, PBI, urinary steroids, potassium
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DOSAGE AND ROUTES All doses in PE (phenytoin sodium equiva- lent) Status epilepticus • Adult/child: IV 15-20 mg PE/kg Nonemergency/maintenance dosing • Adult/adolescent >16 yr: IM/IV 10-20 mg PE/kg; 4-6 mg PE/kg/day (mainte- nance)
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Available forms: Inj 50-mg/mL vials
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Administer: Injectable routes • Give IM/IV; the dosage, concentra- tion, and infusion rate of fosphenytoin should always be expressed, pre- scribed, and dispensed in phenytoin sodium equivalents (PE); exercise ex- treme caution when preparing and ad- ministering fosphenytoin; the concen- tration and dosage should be carefully confirmed; fatal overdoses have oc- curred in children when the per mL concentration of the product (50 mg PE/mL) was misinterpreted as the total amount of drug in the vial • Visually inspect for particulate matter and discoloration before use IV INFUSION route • Before infusion, dilute in 5% dextrose or 0.9% saline solution to a concentra- tion ranging from 1.5 to 25 mg PE/mL
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Assess:
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Evaluate: • Therapeutic response: decrease in se- verity of seizures
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CLINICAL CONSIDERATIONS
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Patient and caregiver information: • About the reason for, expected out- comes of treatment • Not to use machinery or engage in hazardous activity, since drowsiness, diz- ziness may occur • To carry emergency ID denoting prod- uct use, name of prescriber • To notify prescriber of rash, bleeding, bruising, slurred speech, jaundice of skin or eyes, joint pain, nausea, vomiting, severe headaches, depression, suicidal thoughts • To keep all medical appointments, in- cluding those for lab work, physical assessment • To notify prescriber if pregnancy is planned or suspected; not to use in preg- nancy; to avoid breastfeeding • To use contraception while using this product
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PHARMACOKINETICS Metabolized by liver, excreted by kid- neys (minimal), protein binding 95%- 99%, rapidly converted to phenytoin, distributed to CSF, tissue, crosses pla- centa; half-life 15 min; IM: onset unknown, peak 30 min, duration 24 hr, IV onset 15-45 min, peak 15-60 min, duration 24 hr
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• Adult/child: IV 15-20 mg PE/kg Nonemergency/maintenance dosing
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• Adult/adolescent >16 yr: IM/IV 10-20 mg PE/kg; 4-6 mg PE/kg/day (mainte- nance)
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