Some of the factors complicating phenytoin dosing include a narrow therapeutic window, high degree of protein binding, and non-linear pharmacokinetics
Children older than 6 years of age—300 mg per day
Applies to the following strengths: 50 mg/mL; 50 mg; 100 mg; 30 mg; 25 mg/mL; 200 mg; 300 mg; sodium Usual Adult Dose for: Seizures Status Epilepticus Seizure Prophylaxis During or Following Neurosurgery Usual Pediatric Dose for: Seizures Status Epilepticus 1
The recommendations do not take into account the following: (1) existence of interacting drugs (3) inter-patient variability (3) existing disease states which may significantly Loading dose: 1 g divided into 3 doses (400, 300, 300 mg) administered at 2 hr intervals; initiate dosage 24 hr after loading dose Gradually decrease phenytoin dosage by up to 50% when used concomitantly with cenobamate
Maintenance dosage is 4 to 8 mg/kg/day
However, serum drug levels should only be taken when there is a clear indication to guide patient management
The recommended starting dose for adult patients who have received no previous treatment is one 100-mg DILANTIN (extended phenytoin sodium capsule, USP) by mouth three times daily
035), were associated with a greater likelihood of adequate concentrations
Fosphenytoin (FOS) is a phosphate ester prodrug developed as an alternative to parenteral PHT 2
[Osborn HH, Zisfein J, Sparano R: Single-dose oral phenytoin loading
Her serum phenytoin level was 3 times the maximum therapeutic level
The first dose should be given 12-24 hours after the loading dose
The amount of the body mass that the drug distributes into is reflected in its "apparent volume of distribution" (Vd)
1, - 5 However, phenytoin dosing can pose a challenge to clinicians because of its narrow therapeutic range and nonlinear pharmacokinetic profile
Oral (except suspension) Loading dose: Only when indicated for inpatients
2 micron filter must be used and infusion completed within 1 hour of preparation
Phenytoin (but not fosphenytoin ) is incompatible with any of the benzodiazepines and will precipitate if infused through the same IV line; the same Dilantin (Phenytoin) Loading: IV vs
3 g) was given to 44 patients with recent seizures and no detectable serum phenytoin level
In the pediatric population, a loading dose of 15-20 mg/kg of phenytoin sodium intravenously will usually produce plasma concentrations of phenytoin within the generally accepted therapeutic range (10-20 mcg/mL)
Common adverse events include pruritus, nystagmus An order is written for phenytoin IV
Over how many minutes should the dose be administered? Round nearest whole number
Reduction of phenytoin dose may be required based on serum phenytoin concentrations and clinical response
Loading dose (if not previously on phenytoin): IV, Oral: 15 to 20 mg/kg; if currently on phenytoin, reloading dose should be based upon serum concentrations and recent dosing history; an oral loading dose should be divided into 3 doses and administered every 2-4 hours to decrease GI adverse effects and to ensure complete oral absorption
305)
A single 18 mg/kg dose of oral phenytoin capsules or suspension (mean dose, 1
Phenytoin
Dosage must be individualised and adjusted according to clinical A loading dose of 15 to 20 mg/kg of Phenytoin Sodium injection intravenously will usually produce serum concentrations of phenytoin within the generally accepted serum total concentrations between 10 and 20 mcg/mL (unbound phenytoin concentrations of 1 to 2 mcg/mL)
Phenytoin loading dose should be calculated on the basis of IBW plus the product of 1
IV Loading dose 20mg/kg (see Table 1) given via intravenous infusion
Despite these measures, low phenytoin leve can still ls be observed and therefore administration through enteral feeding tubean is only recommended if there is no alternative
Following administration of exact dose of Phenytoin infuse 2 mLs of Sodium Chloride 0
ΔCp = Dose ∗ S Vd Δ C p = D o s e ∗ S V d
In summary, patients with renal failure on phenytoin present unique problems in management
Those 100 kg or more who received less than 15 mg/kg were found to have significantly lower postload concentrations than those that received 15 mg/kg or more regardless of total dose (11
Some authorities have advocated use of an oral loading dose of phenytoin in adults who require rapid steady-state serum levels and where intravenous administration is not desirable
Fosphenytoin offers many advantages over phenytoin: minimum phlebitis, complete IM absorption, and the ability to administer the drug much more rapidly
In a woman taking phenytoin 500 mg daily in 2 divided doses 12 hours apart, breastmilk phenytoin levels were 0
4
Loading dose: Give successive boluses of 1-2 mg/kg every 5 minutes, up to a total of ~5 mg/kg cumulative dose
g Oral: Recommended dose: 100 to 200 mg orally once a day
The following equation is a simple pharmacokinetic equation to estimate a loading dose or resulting serum concentration of a drug
Oral or nasogastric administration should be used, whenever
Serum samples to determine free and total
How can I tell if the phenytoin concentration is
Loading dose (mg) Median (IQR; min/max) 1378 (629; 500/2614) Mean: 1356: Loading dose (mg/kg) Median (IQR; min/max) 19 (5; 4/31) Mean: 18: Maintenance dose (MD)
Phenytoin (but not fosphenytoin ) is incompatible with any of the benzodiazepines and will precipitate if infused through the same IV line;
3 g) was given to 44 patients with recent seizures and no detectable serum phenytoin level
In the pediatric population, a loading dose of 15-20 mg/kg of phenytoin sodium intravenously will usually produce plasma concentrations of phenytoin within the generally accepted therapeutic range (10-20 mcg/mL)
(2
The pharmacist will put the dose into 50 mL NS
Background and objectives: The appropriate loading dose strategy for phenytoin/fosphenytoin in overweight patients is unknown
An increase, up to two capsules three times a day may be made, if necessary
The health care professional is about to administer a loading dose of phenytoin IV
Doses adjusted depending on plasma levels
Introduction: We aimed to evaluate the pediatric fosphenytoin dosing regimen, including optimal timing for the measurement of total serum phenytoin concentration (C PHT)
45 ± 0
It is in the anticonvulsants class of drugs
3 g) was given to 44 patients with recent seizures and no detectable serum phenytoin level
Phenytoin
The usual dose to treat epilepsy is: adults – 200mg to 500mg a day, taken as 1 or 2 doses
The drug should be injected slowly intravenously at a
Phenytoin loading dose should be calculated on the basis of IBW plus the product of 1