Transcript Chapter 16 Cholinesterase Inhibitors

Chapter 10
Drug Therapy in Pediatric Patients
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Pediatric Patients
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All patients younger than16 years
Respond differently to drugs than the rest of
the population
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More sensitive to drugs than other patients are
Show greater individual variation
Sensitivity due mainly to organ system immaturity
Increased risk for adverse drug reaction
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Pediatric Patients
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Ongoing growth and development
Different age groups: different challenges
Two-thirds of drugs used in pediatrics have
never been tested in pediatrics.
Two laws
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Best Pharmaceuticals for Children Act—2002
Pediatric Research Equity Act of 2003
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Pediatric Patients
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20% of drugs were ineffective in children
even though they were effective in adults.
30% of drugs caused unanticipated side
effects, some of them potentially lethal.
20% required dosages different from those
that had been extrapolated from dosages
used in adults.
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Pediatric Patients
Premature infants • (less than 36 weeks’ gestational age)
Full-term infants
• (36–40 weeks’ gestational age)
Neonates
• (first 4 postnatal weeks)
Infants
• (weeks 5–52 postnatal)
Children
• (1–12 years)
Adolescents
• (12–16 years)
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Pharmacokinetics:
Neonates and Infants
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Absorption
Distribution
Hepatic metabolism
Renal excretion
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Drug Therapy in Pediatric Patients
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Pharmacokinetics: neonates and infants
Determining the concentration of a drug at its
sites of action
Determining the intensity of duration of
response
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Elevated drug levels = more intense response
Delayed elimination = prolonged response
Immaturity of organs puts patient at risk for both of
these responses.
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Fig. 10-1. Comparison of plasma drug levels in adults and infants.
A, Plasma drug levels following IV injection. Dosage was adjusted for body weight. Note that
plasma levels remain above the minimum effective concentration (MEC) much longer in the
infant. B, Plasma drug levels following subQ injection. Dosage was adjusted for body weight.
Note that both the maximum drug level and the duration of action are greater in the infant.
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Drug Therapy in
Neonates and Infants
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Increased sensitivity in infants due to:
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Immature state of five pharmacokinetic processes:
• Absorption
• Protein binding of drugs
• Blood-brain barrier
• Hepatic metabolism
• Renal drug excretion
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Pharmacokinetics:
Neonates and Infants
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Absorption
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Oral administration
Intramuscular administration
Percutaneous absorption
Distribution
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Protein binding
Blood-brain barrier
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Pharmacokinetics:
Neonates and Infants
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Hepatic metabolism
Renal excretion
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Pharmacokinetics: Children
Age 1 Year and Older
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Most pharmacokinetic parameters similar to
those in adults
Drug sensitivity more like that for adults than
for children younger than 1 year
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Pharmacokinetics: Children
Age 1 Year and Older
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One important difference
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Metabolize drugs faster than adults
• Markedly faster until age 2 years; then a
gradual decline
• Sharp decline at puberty
• May need to increase dosage or decrease
interval between doses
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Adverse Drug Reactions
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Vulnerable to unique adverse effects related to
organ immaturity and ongoing growth and
development
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Age-related effects
• Growth suppression (caused by glucocorticoids)
• Discoloration of developing teeth (tetracyclines)
• Kernicterus (sulfonamides)
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Dosage Determination
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Dosing is most commonly based on body
surface area (BSA).
Initial pediatric dosing is, at best, an
approximation.
Subsequent doses need to be adjusted.
See formula on next slide.
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Dosage Determination
Approximate dosage for a child =
Body surface area of the child × adult dose
1.73 m²
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Promoting Adherence
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Provide patient education in writing.
Demonstration techniques should be included
as appropriate.
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Promoting Adherence
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Effective education should include
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Dosage size and timing
Route and technique of administration
Duration of treatment
Drug storage
The nature and time course of desired responses
The nature and time course of adverse responses
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