Paediatric Prescribing

Question 1

Paracetamol suspensions
-infant formulation
-6+ formulation

Answer 1

Infant 120mg/5ml
6+ 250mg/5ml

Must be prescribed by mg or mcg
Tell parents the exact volume of paracetamol that needs to be given

Question 2

Aspirin prescribing

Answer 2

DO NOT GIVE IF U16 DUE TO ASSOCIATION WITH REYE’S SYNDROME

Question 3

NSAID prescribing
-use
-cautions

Answer 3

Can be given in addition to paracetamol for pain and fever

Caution if
-significant gastroenteritis
-not drinking well/dehydration risk => impair renal function

Question 4

How does GI motility differ in children

Answer 4

Slower than adults
As child develops, GI motility improves => shorter time for plasma conc peak and duration of action

Question 5

How does intraluminal pH differ in children

Answer 5

After birth, pH is 4
-lower doses of medications broken down by stomach acid needed
-higher doses of weakly acidic drugs are needed

By 3, adult pH values reached

Question 6

How does parenteral absorption differ between
-neonates and young children

Answer 6

Thinner, greater BSA => topical meds are more potent

Greater skeletal muscle capillary density => greater absorption of IM meds

Differences in lung architecture => greater systemic absorption of INH meds

Question 7

How does drug distribution differ in children

Answer 7

Greater total body water
-with age, total body water and extracellular fluid compartment decreases
Children have a higher volume of distribution than adults

Less plasma protein binding
-reduced in neonates, some disease states (nephrotic syndrome) => increased amounts of free drug

Question 8

How do Phase 1 and 2 enzymes change as the child develops

Answer 8

Phase 1 - activates drug

Most P1 enzymes appear after birth
-before they appear, half lives of medications are very long
-as they become more active, half life drops significantly

Phase 2 - inactivates drug

P2 enzymes develop after birth => increased doses needed

Question 9

If trough level comes back too high, how would you manage the next dose

Answer 9

Prolong dose interval before altering drug dose

Question 9

Drug excretion in children

Answer 9

GFR at birth 2-4ml => adult values by 8-12months

Renal excretion in neonates and preterms reduced due to reduced GFR

Question 10

Weight calcuations for dosing
-actual value
-estimation

Answer 10

Measure babies
-no nappy
Older children
-remove shoes and ideally in underwear

Can use formulas or Broselow tape
APLS
0-12months = (0.5 x age in months) + 4
1-5years = (2 x age in years) + 8
6-12years = (3 x age in years) + 7

Question 11

Rule of thumb for
-newborn baby weights
-average 1 year old

Sense check for paeds weight

Answer 11

Average newborn 3.5kg
Average 1 year old 10kg

Weight = (age + 4) x 2

Question 12

Calculation of maintenance fluids
-formula

Answer 12

Maintenance fluids over 24hrs
1st 10kg => 100ml/kg
2nd 10kg => 50ml/kg
Remaining kg => 20ml/kg

Question 13

Oral rehydration
-when to do it
-route
-how

Answer 13

Where possible unless they are shocked, red flags, or continued vomiting despite oral fluid replacement

Over 4 hrs at 50ml/kg + maintenance
Drink little and often
PO or NG

ORS