www.londondeanery.ac.uk

Safe Prescribing

TRUST NAME:

September 2011

Insert Specialty Schoolof Paediatrics and Child Health

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

insert Specialty School of Paediatrics

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)

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Calculating drug doses:example one: prescribing by weight

ENTER DOSE AGAINST TIME REQUIRED USE ONE ROUTE ONLY FOR EACH ENTRY

REGULAR PRESCRIPTIONMONTH YEAR

March 2015

DOSE DATE

START CHANGE CHANGE 07/03/2015

DATE 07/03/2015 DRUG OTHER INSTRUCTIONS SIGNATURE PHARMACY

ROUTE ORAL TRIMETHOPRIM 2mg/kg at night A.Doctor

INITIALS AD

180mg 180mg

2000 11mg 180mg

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• 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)

Calculating drug doses:example two: prescribing by age

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

REGULAR PRESCRIPTIONMONTH YEAR

March 2011

DOSE DATE

START CHANGE CHANGE 07/03/2011

DATE 03/07/2011 DRUG OTHER INSTRUCTIONS SIGNATURE PHARMACY

ROUTE ORAL CO-AMOXICLAV 125/31 SUSPENSION A.Doctor

INITIALS AD

6 95mls

145mls

18  

225mls

insert Specialty School of Paediatrics

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

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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 FluidsCalculating deficit in dehydration

•This is based on child’s weight and % dehydration•Calculation for fluid deficit for %dehydration:–(%dehydration/100) x weight (kg) x 1000mlTHIS 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

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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/HR A.doctor

insert Specialty School of Paediatrics

Principles of prescribing fluidsin 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= (500/300) x 7.5mmol= 12.5mmol – Potassium in 500mL bag= (500/300) x 5mmol = 8.3mmol = 8mmol

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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 CHLORIDEPOTASSIUM CHLORIDE

12.5mmol8.3mmol

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