Pharmacology

Question 1

Why is there differences in the way children respond to medications?

Answer 1

Altered pharmacokinetics and pharmacodynamics

Question 2

What is safe and effective use of drugs complicated by in children?

Answer 2

• a lack of acute dosage data,
• a lack of appropriate formulations allowing accurate dosage and delivery
• difficulty in detecting ADRs.

Question 3

WHat can occur in the postnatal period?

What can occur due to breastfeeding?

Answer 3

• In the immediate postnatal period problems may arise t_hrough in utero exposure and transplacental transfer of drugs to the infant._
• Breast fed infants can be affected by their mothers medication

Question 4

What sort of drug regimens should we aim for in children?

Answer 4

• Most simple dosage regime should be used for children as it makes compliance better and easier for parents to administer.

Question 5

What age can off label medicines be used over?

What are unlicensed medicines?

Answer 5

• Off label medicines are licensed for human use but not for use in children below a certain age such as 16 or 18 years
• Unlicensed medicines have no licence for human use in this country - including medicines which are reformulated for easy use in children

Question 6

In paediatrics when is unlicensed/off label prescribing normally used?

Answer 6

• When a formulation is administered via a route not intended
• Ie giving drug as a liquid rather than tablet/injection

Question 7

What classes as unlicensed medicine?

Answer 7

• Medicines used at a different dose to that recommended
• Children below stated recommended age limit
• Medicines without a licence, including those being used in clinical trials

Question 8

What are the stats on unlicensed use?

Answer 8

• In neonates 60-90% of medicines are off label
• In children 10-50% of medicines off label

Question 9

What are the risks of using drugs off label/unlicensed?

Answer 9

• Of label use gives increased rate of ADRs

Question 10

Why is there increased risk to neonates and infants?

Answer 10

• Neonates/infants are more sensitive to drugs than adults
  
  • due mainly to organ system immaturity
• Neonates/infants are at increased risk for adverse drug reactions
• Young patients show greater individual variation

Question 11

In which stage is there a higher incidence of therapeutic errors?

Answer 11

early post natal period

Question 12

What is the risk of paroxetine when used in children??

Answer 12

4x increase in suicide when compared to placebo

Question 13

What routes may drugs be administered by?

Answer 13

• oral
• parenteral
• topically
• rectally

Question 14

How is oral route affected by childhood administration?

Answer 14

• Reduced gastric acid and delayed gastric emptying.Adult levels reached at 3 years
• Absorption reaches adult values by 6-8 months.
• Bioavailability of drugs with high hepatic clearance and first pass elimination is reduced and highly variable.
• Drugs which rely on entero-hepatic circulation such as cyclosporin also highly variable.

Question 15

How is skin route affected by childhood administration?

Answer 15

Is enhanced in infants and children, especially with damaged skin of an occlusive dressing - such as steroids

Question 16

How is rectal route affected by childhood administration?

Answer 16

• Avoids first-pass metabolism.
• Not ideal as significant variation, few preparations, trauma.

Question 17

How is IV route affected by childhood administration?

Answer 17

Delayed or uncertain delivery

Question 18

What is the effect on drug distribution in children?

Answer 18

• In terms of drug dosage this means that larger initial doses on a mg/kg body weight need to be given to achieve correct plasma concentration
• However after the loading dose the dosage interval may need to be increased or the daily dose decreased to compensate for the decreased hepatic function or decreased renal elimination

Kids have: higher extracellular fluid level, more body water content, lower fat as neonate and high fat as infant

Question 19

What is the effect of a developing BBB on drug uptake in kids?

Answer 19

• Drugs and other chemicals have relatively easy access to the CNS
• Infants especially sensitive to drugs that affect CNS function causing CNS toxicity

Question 20

Childhood differences in drug elimination vs adults?

Answer 20

• In the neonate liver metabolism is immature, thus drugs eliminated by the liver have a longer t1/2
• This results in a longer time to reach steady state (4xt1/2), an increase in steady state concentration

Question 21

Excretion/metabolism in older child?

Answer 21

• Because of significant changes in hepatic metabolism the dosage of some drugs such as anti-epileptics need to be greater on a mg/kg basis in 1-8 year old children than in adults.
• This is because hepatic metabolism is more rapid and t1/2 shorter.

Question 22

How is half life of drugs affected in children?

Answer 22

• Renal excretion is decreased in neonates and shows progressive maturation with age.
• Adult values are achieved at 3-6 months and tubular function at 12 months.
• Consideration of renal function is most important in the neonate
• For most drugs t1/2 is prolonged

Question 23

How can the sensitivity of drugs be increased in children?

Answer 23

• fever
• dehydration (increases the effects of many drugs)
• acidosis (decreased cellular penetration of basic drugs)

Question 24

Difficulties in pharmacology for teenagers?

Answer 24

• major changes in hormone secretion, growth and behaviour
• Growth Major changes in bodyweight
• Noncompliance
• Suicide attempts common
• Illicit drugs

Question 25

What way can parents/patients report suspected side effects of their medications?

Answer 25

Yellow Card

(patient education - Health Promotion)