Drug use in the neonate Flashcards
What is the most effective reliable method of drug administration to a neonate and why?
Intravenous
- you know exactly how much drug is being absorbed into circulation to have an effect
- removes variables such as vomiting and hepatic first pass effect
What factors affect the absorption of a drug given IM to a neonate?
- less muscle mass
- thinner cellular membranes and increased capillary density
- immature circulatory system
what other factors affect drug absorption in the neonate, particularly oral?
- immature GI tract - small surface area, altered pH changes ionisation, changes in bile salt pool
- decreased gastric emptying
- less bacterial colonisation of intestines
- vomiting/reflux
- reduced compliance
What factors influence drug distribution in the neonate?
- body water:fat percentage (low body fat: high body water)
- protein binding - lower plasma proteins, bilirubin competes for binding sites on proteins
- immature blood-brain barrier
What factors influence drug metabolism in the neonate?
- hepatic blood flow increases with age
- immature liver enzymes has variable effect
What factors influence drug elimination in the neonate?
- immature renal function - lower GFR, generally drugs excreted by liver have prolonged elimination half-life
- gestational age
- adequate fluid intake
Why are antimicrobials commonly used in neonates?
- immature immune systems
- excessive use has contributed to development of antibiotic resistance - consider judiciousness and safety
What are the risks associated with antimicrobial use in neonates?
- elimination of protective normal flora
- unknown long term impacts
Why are diuretic drugs used in neonates?
- hypertension
- congestive heart failure
- renal dysfunction
What are 2 risks of IV administration in neonates?
- potential for overdosage due to incorrect calculations
- potential for infection through IV access site
Why do neonates tend to be at higher risk of dosage calculation errors?
- complex factors influence pharmacokinetics
- individualised dosing calculations
- some drugs need to be diluted
- slow IV rates
What methods are used to calculate drug dosages in the neonate
- weight per kilogram
- body surface area
What is the formula for calculating neonatal drug dosages according to weight per kilogram?
dose to be given = recommended dose (mg/kg) x weight (kg)
What is the definition of a neonate?
A baby within it’s first 28 days of life.
What strategies may decrease the risk of drug errors for neonates?
- double checking calculations
- accessible examples of calculations
- using standardised drug preparations and dosing
- asking questions about whether a drug should be administered
- volume should feel appropriate
What is the trade name for benzylpenicillin?
BenPen
What is the usual indication for benzylpenicillin in neonates?
antibiotic for treatment of susceptible organisms (e.g GBS, congenital syphilis)
What is the stock strength and usual dosage of benzylpenicillin for neonates?
600mg vial (as powder for reconstitution with water for injection)
depending on and and indication around 50mg/kg/6-12 hrly
as IM or slow IV over 3-5 minutes
What adverse effects are associated with benzylpenicillin use in neonates?
- hypersensitiviy
- rash
- diarrhoea
- seizures at high doses
- haemolytic anaemia
What is the usual indication for gentamicin in neonates?
aminoglycoside antibiotic for treatment of infections caused by susceptible organisms e.g. e.coli, pseudomonas, klebsiella
What is the stock strength and usual dosage of gentamicin for neonates?
80mg/2ml ampoules
IV is given diluted as a 10mg/mL solution over 10 minutes
IM is used undiluted
dose depends on gestation, given 24-48 hourly
What precautions/side effects are associated with the use of gentamicin in neonates?
- high risk medication
- can cause renal impairment and deafness
- usually used with therapeutic drug monitoring loking at area under curve, peak and trough levels of drug over time
What is the trade name of caffeine citrate?
Cafnea
What is the usual indication for caffeine citrate in neonates?
- stimulates inspiratory drive and increases sensitive of medullary centre to CO2
- used for prevention or treatment of apnoea associated with prematurity, infection or anaesthesia and to aid extubation of ventilated babies
What is the stock strength and usual dosage of caffeine citrate for neonates?
available as oral solution 10mg/ml or 50mg/5 ml ampoule for IV infusions
loading dose is 20mg/kg with maintenance dose of 5-7.5mg/kg/day at least 24 hours later (need to dilute maintenance dose)
- give oral dose with feeds
- routine monitoring of drug levels not required
What adverse effects are associated with caffeine citrate?
- nausea/vomiting
- gastric irritation
- agitation
- tachycardia
- diuresis
- overdose - arrhythmias and seizures
What is the trade name of Vitamin K (phytomenadione)?
Konakion
What is the usual indication for phytomenadione in neonates?
- prophylaxis for vitamin K deficiency bleeding in the newborn
- no colonisation of gut with bacteria that produce vitamin k, poorly transferred across placenta and low concentrations in breastmilk, vital for clotting pathways
When should phytomenadione be given to neonates?
- with maternal consent within 24 hours of birth
What is the usual stock strength, route and dose of phytomenadione in neonates?
2mg/0.2mL ampoules
Can be given IM (preferred) or orally in 3 doses
usual dose is 1mg (0.1ml) IM at birth
if orally 2mg(0.2ml) at birth, 3-5 days and 4 weeks, last dose omitted if formula fed
What adverse effects are associated with phytomenadione?
- very few
- facial flushing, sweating and unusual taste
- rarely anaphylaxis or injection site reactions
What is the protocol if there is a neonatal drug error or near miss?
- location specific
- assess clinical situation
- report incident to shift coordinator and medical officer
- seek advice from pharmacy
- inform patient as appropriate
- documentation
What is therapeutic drug monitoring?
Therapeutic drug monitoring is the individualisation of dosage by maintaining plasma or blood drug concentrations within a target therapeutic range to maximise therapeutic effects and avoid adverse effects
Which neonatal drugs are often used with TDM?
- caffeine citrate
- phenobarbitol
- phenytoin
- gentamicin
- vancomycin
- digoxin
What 7 pieces of information are required to accurately perform TDM?
- Time of sample in relation to last dose
- Duration of treatment at the current dose levels
- Dosing schedule
- Age and gender of patient
- Other concurrent drug therapies
- Relevant disease states
- Reason TDM requested i.e. suspected toxicity or lack of efficacy.
What is the trade name of beractant? and what is its usual indication in neonates?
- Survanta
- pulmonary surfactant used for prevention or treatment of respiratory distress syndrome
What is the stock strength and usual dose of beractant in neonates?
- 25mg/8mL vial stored in refridgerator, warm to room temp before use
- usual dose is 4mL/kg/dose administered through intratracheal tube
- up to 4 doses at 6 hourly invervals
What adverse effects may be associated with beractant?
- transient bradycardia
- oxygen desaturation
- ETT reflux
- pallor
- vasoconstriction
- hypo/hypertension
- apnoea
What is the definition of apnoea in neonates?
- no effective respiratory effort for 20 seconds or shorter if associated with bradycardia
What is the usual management for apnoea in neonates?
caffeine citrate
Why may sucrose be given to neonates?
- for relief of procedural pain
- effect lasts 5-8 minutes
- more effective if combined with sucking
What is the usual dose for sucrose in the healthy term neonate?
stock strength 33% sucrose solution
0.2-1mL PO max dose 5ml
