Drugs in Health and Disease 2 (Prescribing in children)

Question 1

How is the size of the paediatric matter affect prescribing?

Give an example of this

Answer 1

• Range from 0.5-90kg
• Paediatric prescribing is by weight- with adult ceiling
• Some drugs by surface area

Furosemide 40mg daily in adult, 1mg/kg daily
Growth hormone

Question 2

There is scope or confusions with administering small doses

How should these be written?

Answer 2

Write in full
- micrograms, nanograms

Don’t use unnecessary decimal points

• 3mg as opposed to 3.0mg
• 100 micrograms, not 0.1mg

Question 3

Describe the altered kinetics in neonates

Answer 3

Immature liver enzymes

• opiates are cleared slowly
• “short acting” benzodiazepines metabolised slower

Low GFR at birth
- give lower dose at wider intervals for aminoglycosides

Dosage schedules change after first few weeks

Question 4

For the following drugs, what adverse effects are more pronounced in children

1. Benzodiazepines/opiates
2. Chloramphenical
3. Aspirin
4. Phenobarbitone vs amphetamines

Answer 4

1. Apnoea in infants, immature liver + resp control
2. “grey baby” reaction in neonates, liver immaturity
3. Reyes syndrome
4. Paradoxical psychotropic effects

Question 5

What considerations should you make in terms of delivery of medications to children?

Answer 5

Avoid unnecessary pain:

• IM injections rarely used,
• Long term venous access devices used if repeated IV infusions needed

Liquid preparations (if available)

• young children have difficulties swallowing tablets
• tablet doses are inflexible
• problems for slow release formulations

Question 6

How would you give inhaled medications

Answer 6

• Metered dose inhaler requires complex coordination
• at school age; dry powder inhaler
• preschool age: MDI+ spacer +/- mask
• always specify the delivery device

Question 7

What are the licensing issues surrounding paediatric use

Answer 7

• many drugs dont have paediatric licensing (difficulties in drug trials)
• “off licence” prescribing: where there is no licence, or child is below licensed age, its legal but the prescriber takes responsibility,

Question 8

Consider the drugs affect the ductus arteriosus (passage between pumonary artery and aorta)

What drugs are used to close a patent ductus arteriosus?

Answer 8

Indomethacin/Ibuprofen

• COX1 inhibitors which prevent prostaglandin synthesis
• IV/oral (no liquid prep)
• Variable availability
• side effects: renal failure (due to decreased GFR), bleeding (due to decreased platelet function), necrotising enterocolitis (decreased gut blood flow)

Question 9

Consider the drugs affect the ductus arteriosus (passage between pulmonary artery and aorta)

What drugs are used to keep a patent ductus arteriosus?

Answer 9

Prostaglandin E1 or E2

• IV infusion 10nanog/kg/minute;
• Oral 20microg/kg 2hourly
• Problems: apnoea