Names and pronunciation
(fen′i-toh-in) Dilantin, Tremytoine
Source page 1047
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Individual generic drug information
Extracted information for phenytoin only.
(fen′i-toh-in) Dilantin, Tremytoine
Source page 1047
Func. class.: Anticonvulsant; antidys- rhythmic (IB) Func. class.: Laxative, saline
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Chem. class.: Hydantoin
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ACTION: Inhibits spread of seizure activity in motor cortex by altering ion transport; increases AV conduction ACTION: Increases water absorption in the small intestine by osmotic action; laxative effect occurs by increased peristalsis and water retention P
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USES: Generalized tonic-clonic seizures; status epilepticus; nonepileptic seizures associated with Reye’s syndrome or after head trauma; complex partial seizures USES: Constipation, bowel or rectal preparation for surgery, exam
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Unlabeled uses: Digoxin toxicity; sei- zures, prophylaxis in head trauma, sub- arachnoid hemorrhage
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Extracted information for phenytoin only.
CONTRAINDICATIONS: Preg nancy, hypersensitivity, bradycardia, SA and AV block, Stokes-Adams syndrome Precautions: Hypersensitivity to carBA- Mazepine, barbituates, succinimide, Geriatric patients, renal/hepatic disease, petit mal seizures, hypotension, myocar- dial insufficiency, Asian patients posi- tive for HLA-B1502, hepatic failure, acute intermittent porphyria, psychiatric condi- tion, abrupt discontinuation, agranulocy- tosis, alcoholism, bone fractures CONTRAINDICATIONS: Hyper sensitivity, rectal fissures, abdominal pain, nausea, vomiting, appendicitis, acute surgical abdomen, ulcerated hemorrhoids, sodium-restricted diet, renal failure, hyperphosphatemia, hypocalcemia, hypokalemia, hypernatremia, Addison’s disease, HF, ascites, bowel perforation, megacolon, imperforate anus
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Black Box Warning: IV use DOSAGE AND ROUTES—NTI Seizures P • Adult: PO 15-20 mg/kg (ext rel) in 3-4 divided doses given q2hr or 400 mg, then 300 mg q2hr × 2 doses; maintenance 4-7 mg/kg/day; IV 15-20 mg/kg, max 25-50 mg/min, then 100 mg q6-8hr • Child: IV/PO 5 mg/kg/day in 2-3 di- vided doses, maintenance 4-8 mg/kg/day in 2-3 divided doses, max 300 mg/day Status epilepticus • Adult: IV 15-20 mg/kg, max 50 mg/min • Child: IV 20 mg/kg/dose Black Box Warning: Give undiluted at ≤50 mg/min (adult) 1-3 mg/kg/min (child); 0.5- 1 mg/kg/min (neonates), monitor for CV reactions and respiratory depression Intermittent IV INFUSION route Black Box Warning: Dilute dose in NS to ≤6.7 mg/mL; complete infusion within 1 hr of preparation; use 0.22- or 0.55-micron in-line particulate final filter between IV catheter and tubing; flush IV line or catheter with NS before and after use; give at ≤50 mg/min (adult), 0.5-1 mg/kg/min (child, infant, neonate) Additive compatibilities: Do not admix Black Box Warning: GI obstruction, renal failure Precautions: Pregnancy Black Box Warning: Colitis, geriatric hy- povolemia, renal disease
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SIDE EFFECTS CNS: Dizziness, insomnia, paresthesias, depression, suicidal tendencies, aggres- sion, headache, confusion, slurred speech, peripheral neuropathy CV: Hypotension, ventricular fibrillation, bradycardia, cardiac arrest EENT: Nystagmus, diplopia, blurred vision ENDO: Diabetes insipidus GI: Nausea, vomiting, constipation, anorexia, weight loss, hepatitis, jaundice, gingival hyperplasia, abdominal pain GU: Nephritis, urine discoloration, sexual dysfunction HEMA: Agranulocytosis, leukopenia, aplastic anemia, thrombocytopenia, meg- aloblastic anemia INTEG: Rash, lupus erythematosus, Stevens- Johnson syndrome, hirsutism, toxic epider- mal necrolysis SYST: Hypocalcemia, purple glove syn- drome (IV), DRESS, anaphylaxis, exacer- bates myasthenia gravis SIDE EFFECTS CV: Dysrhythmias, cardiac arrest, hypo- tension, widening QRS complex GI: Nausea, cramps, diarrhea META: Electrolyte, fluid imbalances
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INTERACTIONS • Do not use with delavirdine; decreased response, resistance Increase: phenytoin effect—benzodiaze- pines, cimetidine, tricyclics, salicylates, valproate, cycloSERINE, diazePAM, chlor- amphenicol, disulfiram, alcohol, amioda- rone, sulfonamides, FLUoxetine, gabapen- tin, H2 antagonists, azole antifungals, estrogens, succinimides, phenothiazines, methylphenidate, felbamate, traZODone Decrease: phenytoin effects—alcohol carBAMazepine, rifAMPin, calcium (high dose), folic acid Drug/Food Enteral tube feeding: may decrease absorp- tion of oral product; do not use enteral feed- ings 2 hr before or 2 hr after dose Drug/Lab Test Increase: glucose, alk phos, GGT Decrease: dexamethasone, metyraPONE test serum, PBI, urinary steroids
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Extracted information for phenytoin only.
Available forms: Susp 25 mg/5 mL; chewable tabs 50 mg; inj 50 mg/mL; ext rel caps 100, 200, 300 mg; prompt rel caps 100 mg Available forms: Enema 7 g phos- phate/19 g biphosphate/118 mL; oral sol 18 g phosphate/48 g biphosphate/100 mL
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Administer: PO route • Do not interchange chewable prod- uct with caps, not equivalent; only ext rel caps to be used for once-a-day dosing • Oral suspension: shake well before each dose given via G tube/NG tube; di- lute susp before administration; flush tube with 20 mL water after dose; hold tube feedings 1 hr before and 1 hr after dose • Allow 7-10 days between dosage changes • Divided PO doses with or after meals to decrease adverse effects • Give 2 hr before or after antacid, en- teral feeding Direct IV route Administer: • Alone for better absorption; do not take within 1-2 hr of other products
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DOSAGE AND ROUTES • Adult: PO 20-30 mL (Phospho-Soda) • Child: PO 5-15 mL (Phospho-Soda) • Adult/child >12 yr: RECT 1 enema (118 mL) • Child 2-12 yr: RECT 1/2 enema (59 mL)
Source pages 1049, 1050
Extracted information for phenytoin only.
Assess: • Phenytoin hypersensitivity syn- drome 3-12 wk after start of treatment: rash, temperature, lymphadenopathy; may cause hepatotoxicity, renal failure, rhabdomyolysis • Serious skin disorders: for beginning rash that may lead to Stevens-Johnson syndrome or toxic epidermal necrolysis; phenytoin should not be used again; may occur more often among Asian pa- tients with HLA-B 1502 • Purple glove syndrome with IV use • Phenytoin level: toxic level 30-50 mcg/ mL; therapeutic level 7.5-20 mcg/mL • Seizures: duration, type, intensity, pre- cipitating factors; obtain EEG periodically; monitor therapeutic level • Blood studies: CBC, platelets q2wk un- til stabilized, then monthly × 12, then q3mo; discontinue product if neutrophils <1600/mm3; renal function: albumin concentration; folic acid levels, LFTs • Mental status: mood, sensorium, affect, memory (long, short), suicidal thoughts/behaviors • Monitor EKG, B/P, respiratory function during IV loading dose; verify potency of IV access port before IV infusion • Monitor EEG function and serum levels periodically • Renal function: monitor for serum al- bumin, dosage adjustment may be needed • Blood dyscrasias: fever, sore throat, bruising, rash, jaundice • Beers: avoid use in older adults unless safer alternatives are unavailable; ataxia, impaired psychomotor function may occur • Pregnancy/breastfeeding: pregnant women should enroll in the Antiepileptic Drug Pregnancy Registry, 1-888-233- 2334; may cause fetal malformations; use other options when possible; breastfeed- ing is not recommended Assess: • Stools: color, amount, consistency; bowel pattern, bowel sounds, flatulence, distention, fever, dietary patterns, exercise; cramping, rectal bleeding, nausea, vomit- ing; if these occur, product should be dis- continued • Blood, urine electrolytes if product used often
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Evaluate: • Therapeutic response: decrease in se- verity of seizures Evaluate: • Therapeutic response: decrease in constipation
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CLINICAL CONSIDERATIONS CLINICAL CONSIDERATIONS
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Patient and caregiver information: • That, if diabetic, blood glucose should be monitored • That urine may turn pink • Not to discontinue product abruptly be- cause seizures may occur • Oral hygiene: about the proper brush- ing of teeth using a soft toothbrush, floss- ing to prevent gingival hyperplasia; about the need to see dentist frequently • To avoid hazardous activities until sta- bilized on product • To carry emergency ID stating product use • That heavy use of alcohol may diminish effect of product; to avoid OTC medications • Not to change brands or forms once stabilized on therapy because brands may vary • Not to use antacids within 2 hr of prod- uct • To notify prescriber of unusual bleed- ing, bruising, petechiae (bleeding), clay- colored stools, abdominal pain, dark urine, yellowing of skin or eyes (hepato- toxicity); slurred speech, headache, drowsiness • To report suicidal thoughts/behaviors immediately • Pregnancy/breastfeeding: to use nonhormonal contraception; to notify pre- scriber if pregnancy is planned or suspected (OTC) Fleet Enema, Phospho-Soda Patient and caregiver information: • Not to use laxatives for long-term ther- apy because bowel tone will be lost • That normal bowel movements do not always occur daily • Not to use in presence of abdominal pain, nausea, vomiting • To notify prescriber if constipation unrelieved or if symptoms of electro- lyte imbalance occur: muscle cramps, pain, weakness, dizziness, excessive thirst • To maintain fluid consumption See Appendix B
Source pages 1049, 1050
Extracted information for phenytoin only.
PHARMACOKINETICS Metabolized by liver, excreted by kidneys, protein binding 90%-95%, half-life 7-42 hr, dose dependent PO: Onset 2-24 hr, peak 11/2-21/2 hr, duration 6-12 hr PO-ER: Onset 2-24 hr, peak 4-12 hr, duration 12-36 hr IV: Onset 1-2 hr, duration 12-24 hr PHARMACOKINETICS Onset 30 min-3 hr, excreted in feces
Source pages 1048, 1050
Filter the extracted dose blocks for this individual drug.
• Adult: PO 20-30 mL (Phospho-Soda)
Candidate age grouping · source pages 1049, 1050
• Adult/child >12 yr: RECT 1 enema (118 mL)
Candidate age grouping · source pages 1049, 1050