Phenytoin  Dilantin ®

Usual Diluents

NS

Standard Dilutions   [Amount of drug]  [Infusion volume]  [Infusion rate]

May be given IVPush -See comments. [100 mg] [50 ml] [5-15 min] [200-500 mg] [100ml] [15-30 min] [501-1500 mg] [250 ml] [See comments]

Stability / Miscellaneous

Label: Do not Refrigerate / Use an inline 0.22u filter.  EXP: 2 HOURS (RT)  Another source:  Concentrations up to 6.7 mg/ml are stable up to 24 hours (insignificant loss).  Ideally, the solution should be infused within 1 hour of mixing. Constantly monitor for precipitate formation.  Infusion rates:  Maximum: 50 mg/min  Recommended rate for  most adults: 40 mg/min.  Elderly (rate): 20 mg/min.  Usual IV loading dose: 15 mg/kg TBW  Maintenance dose (started 18-24h after load): 6 mg/kg ibw IV/PO in divided doses q8 to 12h. (The IV maintenance dose should never be given qd in a single dose).  Oral loading: 16 mg/kg TBW (use adjBW if obese) given in 3 to 4 divided doses at q2h intervals (divided doses increase bio-availability as well as decrease potential for gastrointestinal side effects such as N&V).  The maximum single oral dose should not exceed 400mg in order to minimize gastrointestinal side effects and increase absorption.  Sampling: 18 to 24h after loading dose, then q5 to 7 days to assess trend. Average time to steady state: 10 to 14days.  Half-life: 7-42hrs (average=24h).  Capsules/injection= 92% phenytoin. Elixir/tabs=100% phenytoin.  Equation used to estimate the dose req'd to increase current level to normal range if subtherapeutic: = [0.7 x IBW x (15 - current level) ] / 0.92* * (if capsules/injection used)  Adjusted phenytoin concentration if low serum albumin= measured total concentration / [ (0.2 x albumin) + 0.1]