Seizure - Medication


These guidelines have been produced to guide clinical decision making for the medical, nursing and allied health staff of Perth Children’s Hospital. They are not strict protocols, and they do not replace the judgement of a senior clinician. Clinical common-sense should be applied at all times. These clinical guidelines should never be relied on as a substitute for proper assessment with respect to the particular circumstances of each case and the needs of each patient. Clinicians should also consider the local skill level available and their local area policies before following any guideline. 

Read the full CAHS Emergency Department disclaimer


To guide staff with the use of seizure medications in the Emergency Department.


  • Prepare infusion immediately before use and discard if not commenced within 30 minutes of preparation. Do not prepare more than required dose.
  • Check for haziness or precipitation before and throughout the infusion.
  • Compatibility note: Phenytoin sodium is ONLY compatible with sodium chloride 0.9%. Do not administer with any other drugs or fluids.

Flushing Lines

  • Flush IV lines before and after Phenytoin sodium administration with sodium chloride 0.9%.
  • After the drug is given, give the flush at the same rate as the infusion.  The volume of flush must be sufficient to clear the line of all remaining drug.


Monitoring patients receiving IV phenytoin sodium, phenobarbital (phenobarbitone) and levetiracetam

  • Infusion rates are different in ward areas – refer to PCH Medication Monographs (WA Health only).
  • For the loading dose monitor BP, continuous ECG, pulse and respiration every five minutes during the infusion and for 30 minutes after completion of the flush.
  • If bradycardia or hypotension occurs, stop the infusion and call the doctor.  Consider recommencing the infusion at a lower rate.  

Seizure medication preparation 

Drug Route
Diluent Volume of Diluent
Dose Precautions
Midazolam (WA Health only)
(vial strength 5mg/mL)
Buccal Nil Neat 0.3mg/kg


Midazolam (WA Health only
(vial strength 5mg/mL)
Sodium chloride 0.9% Draw up 2mL of midazolam (10mg) and add 8mL sodium chloride 0.9% to give 10mg in 10mL (1mg/mL) 0.15mg/kg

Maximum 10mg/dose

Midazolam (WA Health only
(vial strength 5mg/mL)
Intramuscular Nil Neat


Maximum 10mg/dose

Consider muscle site appropriate to the age of child and volume to be administered
Diazepam (WA Health only)
(vial strength 5mg/5mL) 

Rectal  Nil  Neat  0.5mg/kg

Maximum 20mg/dose
Diazepam (WA Health only)
(vial strength 10mg/2mL) 


Nil Neat 0.25mg/kg

Maximum 10mg/dose
Over at least 3 to 5 minutes
(vial strength 1mg/mL) 


Intravenous Use diluent provided (ampoule) Mix 1mg ampoule with 1 mL of diluent to give a 0.5mg/mL solution

Repeat after 15 minutes if necessary

Maximum 1mg/dose


Over at least 2 minutes

Can cause respiratory depression especially if given quickly or combined with barbiturates or other benzodiazepines

Intravenous infusion preparation



Volume of Diluent

Rate of Administration

Precautions and Side Effects

Phenytoin sodium (WA Health only)
(IV loading dose)
Max dose = 1.5g
Sodium chloride 0.9%
(not compatible with glucose or other drugs, insert 2nd IV line)

Children ≤ 30kg
(add drug directly into a 100mL bag of sodium chloride 0.9%)

Children > 30kg
(add drug directly into a 250mL bag of sodium chloride 0.9%)


Infuse over 20 minutes if dose is 1g or less.

Infuse over 30 minutes if dose is greater than 1g (max 1.5g)

(controlled using an infusion pump)

  • See above for flushing lines and monitoring requirements.
  • Take into account any Phenytoin received recently (including orally)
  • Do not prepare more than the required amount
  • Line must be flushed before and after with sodium chloride 0.9% 
  • ECG and BP monitoring is essential
  • Reduce the rate of administration if bradycardia or hypotension develop
Phenobarbital (WA Health only)
(IV loading dose)
Max dose =1g

Sodium chloride 0.9% 
Glucose 5% 
Dilute to 20mg per 1mL of diluent Over 20 minutes
  • Respiratory depression
  • Hypotension
  • Incompatible with many drugs
  • Avoid extravasation
  • Effects are potentiated by concurrent use of other barbiturates or benzodiazepines
Midazolam (WA Health only)
(continuous infusion)
Sodium chloride 0.9%  
Glucose 5%

Midazolam 2.5mg/kg (max 125mg) in 50mL of diluent.

(a rate of 1 mL per hour  =
Child ≤ 50kg: 50 microgram/kg/hour
Child > 50kg: 2.5mg/hour)

50-250 microgram/kg/hr
  • Should be used in ventilated patients in intensive care unit
(IV loading dose)
Max dose = 3g

Sodium chloride 0.9%
Dilute 1:1
(minimum volume 10mL)
Infuse over 5 minutes
  • Incompatible with many drugs


  1. AMH Children’s Dosing Companion (2020) Australian Medicines Handbook Pty Ltd
  2. Australian Injectable Drugs Handbook (AIDH) - 8th Edition 2020


Endorsed by:  Drug and Therapeutics Committee  Date:  Jun 2020

 Review date:   Apr 2023

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