Insert Specialty School
of Paediatrics and Child Health
Safe Prescribing
TRUST NAME:
September 2011
www.londondeanery.ac.uk
insert Specialty School of Paediatrics
Objectives of this session are
• To understand the importance of safe prescribing
• To become familiar with the local drug chart
• To learn how to prescribe for children
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Why is prescribing important?
• Prescribing errors are common from all grades of
doctors
• Many clinical incidents are due to prescribing
errors
• Prescribing errors can be fatal
• Prescribing for children is different to prescribing
for adults
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Why is prescribing different in children?
Children are not small adults
Factors include:
• Body weight
• Body composition
• Surface area
• Nutritional status
• Organ maturation
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We will cover the following
–Dose calculation based on age and weight
–Prescribe fluids
–Prescribe neonatal fluids
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Principles of prescribing for children
• Many medications for children come in liquid form
• It is usually more appropriate to prescribe in actual dose
(e.g. mg) of drug rather than in volume (mL).
• Medications have different concentrations
– e.g. paracetamol can be 120mg/5mL or 250mg/5mL
• Importance of difference between micrograms and mg.
• Use generic drug names when prescribing
• Prescribe sensibly - It is important to consider drug
rounding
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Principles of prescribing for children:
age & weight
All drug charts must have a recent weight and DOB
• Calculations of drug doses depend on age, weight
or surface area of a child
• Medication is usually prescribed based on age or
weight
• The correct doses should be checked in the BNFC
or local guidelines
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Calculating drug doses:
example one: prescribing by weight
• Romeo, a 4-week-old infant weighs
5.5kg. He requires prophylactic
Trimethoprim for prevention of urinary
tract infection.
• How much would you give him?
Use the BNFC App: Click Here
• In this example, we will use the dose for children 1 month
to 12 years of age (2mg/kg, max 100mg at night)
• Workings:
– 5.5kg x 2mg/kg = 11mg at night (orally)
insert Specialty School of Paediatrics
Calculating drug doses:
example one: prescribing by weight
ENTER DOSE AGAINST TIME REQUIRED USE ONE
ROUTE ONLY FOR EACH ENTRY
DATE
DOSE
START
CHANGE CHANGE 07/03/2015
DRUG
DATE
07/03/2015
ROUTE ORAL
INITIALS AD
2000
180mg
180mg
11mg
180mg
REGULAR PRESCRIPTION
MONTH
YEAR
March
OTHER INSTRUCTIONS
TRIMETHOPRIM
2mg/kg at night
2015
SIGNATURE
A.Doctor
PHARMACY
insert Specialty School of Paediatrics
Calculating drug doses:
example two: prescribing by age
• Jimmy, a 4 year old child weighs 16kg
• He has a mild chest infection
• How much oral co-amoxiclav would
you prescribe for him?
• Use the BNFC: Click Here
• Workings:
– We will use the age range instead of weight
– Age = 4 therefore dose = 5mL of 125/31 suspension
three times per day (TDS)
insert Specialty School of Paediatrics
Calculating drug doses:
example two: prescribing by age
ENTER DOSE AGAINST TIME REQUIRED USE ONE
ROUTE ONLY FOR EACH ENTRY
DATE
DOSE
START
CHANGE
DATE
03/07/2011
ROUTE ORAL
INITIALS AD
6
9 5mls
14 5mls
18
22 5mls
CHANGE
REGULAR PRESCRIPTION
MONTH
YEAR
March
2011
07/03/2011
DRUG
OTHER INSTRUCTIONS
CO-AMOXICLAV
125/31 SUSPENSION
SIGNATURE
A.Doctor
PHARMACY
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Principles of prescribing fluids
• Usual maintenance fluid in this trust is [TRUST FLUID]
• Children on intravenous fluids will need daily U&Es (change
based on local trust guidelines)
• Ensure you prescribe:
– Fluid type (concentration)
– Volume (e.g. 500mL bag)
– Rate (mL/hour)
– Additives if required
– ?duration (some trusts)
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Calculating and prescribing
maintenance fluids
• This should be prescribed based on weight:
– For every kg up to 10kg
100mL/kg/day
– For every kg between 10-20 kg
50mLkg/day
– For every kg over 20kg
20mL/kg/day
– This will be the maintenance fluid required over 24 hours
– The total should therefore be divided by 24hours to give a rate in mL/hr
– Consider whether the child requires potassium
insert Specialty School of Paediatrics
Prescribing fluid:
example three – prescribing maintenance fluid
• Abigail, a 10 year old child weighs 32 kg.
• She requires maintenance fluid over the next 24 hours. Please prescribe this.
• If unsure, use the BNFC: Click Here
• Working:
– 10kg @ 100mL/kg/day = 1000mL
– 10kg @ 50mL/kg/day =
500mL
– 12kg @ 20mL/kg/day=
240mL
– 24 hour requirement:=
1740mL = 72.5mls / hour (for 24 hours)
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Prescribing fluid:
example three – prescribing maintenance fluid
Date
Infusion Fluid
Volume
Name of Drug to be
infused
Dose of
Drug
Added
Route
Infusion rate
Signature
14/3/11
O.9%NaCL/5%DEXTROSE
500mL
NIL
-
IV
73mL/HR
A.doctor
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Principles of Prescribing Fluids
Calculating deficit in dehydration
• This is based on child’s weight and % dehydration
• Calculation for fluid deficit for %dehydration:
–(%dehydration/100) x weight (kg) x 1000ml
THIS can be simplified to
– %dehydration x weight x 10= total fluid deficit (mls)
This should be replaced over 24-48 hours
This represents the extra fluid that is needed so should
be added to total maintenance requirements
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Prescribing fluid:
example four: prescribing rehydration fluid
• Chloe, a 10 year old child weighs 32 kg (the same as her friend Abigail in example 3)
• She is clinically 5% dehydrated due to gastroenteritis. Prescribe fluid to rehydrate her
over the next 24 hours. Please prescribe this.
• Working for maintenance:
– 10kg @ 100mls/kg/day = 1000mls
– 10kg @ 50mls/kg/day =
500mls
– 12kg @ 20mls/kg/day=
240mls
– 24 hour maintenance requirement:= 1740mls
• Additional fluid required:
– (%dehydration/100%) x weight (kg) x 1000ml/kg
– (5/100) x 32kg x 1000ml/kg = 1600mls
• Total fluid required in 24 hours= 1740mls + 1600mls = 3340mls
insert Specialty School of Paediatrics
Prescribing fluid:
example four: prescribing rehydration fluid
Date
Infusion Fluid
Volume
Name of Drug to
be infused
Dose of
Drug
Added
Route
Infusion rate
Signature
14/3/11
O.9%NACL/5%DEXTROSE
500ML
NIL
_
IV
139ML/H
R
A.doctor
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Principles of prescribing fluids
in neonates
• Requirements depend on gestation, age (day of life) and
weight
• The usual neonatal fluid is 10% dextrose
• Fluids may or may not require additives
– Usual sodium requirements are 2-6 mmol / kg / day
– Usual potassium requirements are 1-3 mmol / kg / day
– These may change depending on the clinical condition of
the patient
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Prescribing fluids:
example five - prescribing fluids for neonates
• Baby Alfie is born at 37/40
• He weighs 2.8kg
• He was born four hours ago
• Prescribe fluid for Alfie for the next 24 hours (day 1 of life)
• Workings:
– In our trust, we prescribe 60mL/kg/day on day 1 of life with no additives
Alfie will need 60mL/kg x 2.8kg =
168mL/24 hrs
7mL/hour
insert Specialty School of Paediatrics
Prescribing fluids:
example five - prescribing fluids for neonates
Date
Infusion Fluid
Volume
Name of Drug to be
infused
Dose of
Drug
Added
Route
Infusion rate
Signature
14/3/11
10% DEXTROSE
500mL
NIL
_
IV
7mL/HR
A.doctor
insert Specialty School of Paediatrics
Prescribing fluids:
example six - prescribing additives for neonates
• Baby Begum is born at 35 weeks gestation, weighing 2.5kg
• She is 3 days old and you have been asked to prescribe fluid at 120mL/kg/day with
2mmol/kg/day of potassium and 3mmol/kg/day of sodium.
• Workings:
– Fluid: 2.5kg x 120mL/kg/day = 300mL/day = 12.5mL/hour
– Sodium: 2.5kg x 3mmol/kg/day
= 7.5 mmol/day
– Potassium: 2.5kg x 2mmol/kg/day
= 5 mmol/day
– Therefore 300mls of 10% Dextrose + 7.5 mmol of Sodium + 5 mmol of potassium is the
daily requirement
– Fluids are administered in standard 500mL bags so the equivalent doses need to be
calculated to give the correct concentration of fluid.
– Sodium in 500mL bag=
– Potassium in 500mL bag=
(500/300) x 7.5mmol= 12.5mmol
(500/300) x 5mmol = 8.3mmol = 8mmol
insert Specialty School of Paediatrics
Prescribing fluids:
example six - prescribing additives for neonates
Date
Infusion Fluid
Volume
Name of Drug to be infused
Dose of Drug
Added
Route
Infusion rate
Signature
14/3/11
10% DEXTROSE
500mL
SODIUM CHLORIDE
POTASSIUM
CHLORIDE
12.5mmol
8.3mmol
IV
12.5
mL/HR
A.doctor
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Local drug chart
• [spend this time going over your drug chart]
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Trust guidelines & policies
[Outline any specific trust guidelines & policies here]
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Questions?
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Summary
• Don’t forget:
– Age
– Weight
– Show your calculations initially
– Always use local guidelines or BNFC to check doses
– Prescribe in dose rather than mls whenever possible
– If you are ever unsure, always ask for help from a senior
colleague or pharmacist