Pharm III Week 3 - Pediatrics Overview of Pharmacy and Therapeutics

What topics are covered in the pediatric pharmacy lecture?

Pediatric pharmacokinetics and pharmacodynamics; routes of medication administration; pediatric drug-dosing methods; acute otitis media; pharyngitis; community-acquired pneumonia; conjunctivitis; and pediatric GERD.

What is the gestational-age definition of a preterm or premature infant?

Less than 36 weeks' gestation.

What is the gestational-age definition of a term infant in the presentation?

Greater than 37 weeks' gestation.

What is the age range of a neonate?

Less than 30 days of age, corresponding to the first 4 weeks of life.

What is the age range of an infant?

1 month through 1 year of age.

What is the age range of a child?

1 through 12 years of age.

What is the age range of a toddler?

1 through 3 years of age.

What is the age range of a preschool-aged child?

3 through 5 years of age.

What is the WHO age range for adolescence?

10 through 19 years of age.

What does gestational age describe?

How far along a pregnancy is.

What is the first-trimester gestational range?

0-12 weeks.

What is the second-trimester gestational range?

13-27 weeks.

What is the third-trimester gestational range?

28-40 weeks.

What is the lowest gestational age at birth noted in the presentation for an infant who survived into adulthood?

Approximately 22 weeks' gestation.

Why is pediatric age terminology clinically important?

Age and gestational maturity affect organ development, pharmacokinetics, medication selection, dose, and dosing interval.

What does ADME stand for?

Absorption, distribution, metabolism, and excretion.

What is the approximate gastric pH of a neonate or preterm infant?

Approximately 6-7, which is relatively alkaline.

How does neonatal alkaline gastric pH affect weakly acidic drugs?

It decreases their absorption.

Which weakly acidic drugs are listed as having decreased absorption in neonates?

Phenytoin and phenobarbital.

How does neonatal alkaline gastric pH affect acid-labile drugs?

It increases their absorption or bioavailability.

Which acid-labile drugs are listed as having increased absorption in neonates?

Ampicillin and penicillin G.

What percentage of neonatal body weight is total body water?

Approximately 85%-90%.

How does high neonatal total body water affect hydrophilic drugs?

It increases their volume of distribution, potentially diluting serum concentrations.

Why may neonates require a higher mg/kg dose of gentamicin?

Gentamicin is hydrophilic, and the neonate's high total body water increases its volume of distribution.

How do low neonatal fat stores affect lipophilic medications?

They decrease the volume of distribution of lipophilic medications.

Which drug is used as the example of a lipophilic drug affected by low neonatal fat stores?

Diazepam.

How do low neonatal albumin concentrations affect medications?

They decrease protein binding and increase the pharmacologically active free-drug concentration.

Why can low albumin increase drug toxicity in neonates?

A greater proportion of a highly protein-bound medication remains unbound and pharmacologically active.

What is the concern when a drug displaces bilirubin from albumin in a neonate?

Free bilirubin can rise and increase the risk of kernicterus.

Which medication class is specifically associated with bilirubin displacement and kernicterus risk?

Sulfonamides or sulfa drugs.

Which cephalosporin is listed as a concern because of neonatal bilirubin displacement?

Ceftriaxone.

Which drugs should be avoided or used cautiously in neonates because of competitive bilirubin displacement?

Sulfonamides, ceftriaxone, and other medications capable of displacing bilirubin from albumin.

What happens to Phase I and Phase II liver enzymes in neonates?

They are immature.

Which CYP enzymes are specifically underexpressed in neonates?

CYP3A4, CYP2C9, and CYP2D6.

How does immature neonatal hepatic metabolism affect drug clearance?

It reduces the clearance of many hepatically metabolized drugs.

How does reduced neonatal hepatic clearance affect drug half-life?

It prolongs the half-life and increases the risk of accumulation.

Which medication is used as an example of reduced neonatal hepatic clearance?

Theophylline.

Why can theophylline accumulate in a neonate?

Its clearance is reduced because neonatal hepatic enzymes are immature, producing a prolonged half-life.

What percentage of adult GFR is present in a neonate?

Approximately 10%-30% of adult GFR.

What renal tubular processes are immature in neonates?

Tubular secretion and tubular reabsorption.

How does immature neonatal renal function affect renally eliminated drugs?

It decreases elimination, prolongs half-life, and may require extended dosing intervals.

Which medications are used as examples of drugs that may require extended neonatal dosing intervals?

Vancomycin and aminoglycosides.

What dosing intervals may be required for vancomycin or aminoglycosides in neonates?

Approximately every 24-48 hours, depending on the patient.

What monitoring is emphasized for vancomycin and aminoglycosides in neonates?

Close monitoring of serum drug concentrations.

At approximately what age does gastric acid secretion mature?

Approximately 3 months of age.

How does maturation of gastric acid secretion affect medication absorption?

It improves medication bioavailability and makes absorption more similar to that in older patients.

What happens to total body water during infancy and childhood?

It decreases toward approximately 60% of body weight.

How does decreasing total body water affect hydrophilic medications?

It decreases their volume of distribution over time.

What happens to protein binding during infancy?

Protein binding improves, reducing free-drug concentrations.

What happens to hepatic metabolism during infancy?

It accelerates and may exceed adult metabolic activity between approximately 6 and 12 months.

Which CYP enzymes become more active during infancy?

CYP3A4, CYP2D6, and CYP1A2.

Why may some infants and young children clear medications faster than adults?

Hepatic metabolic activity can temporarily exceed adult levels.

What is the estimated GFR at 1 month of age?

Approximately 60% of the adult value.

What is the estimated GFR at 3 months of age?

Approximately 75% of the adult value.

What is the estimated GFR at 6 months of age?

Approximately 80%-90% of the adult value.

What is the estimated GFR at 1 year of age?

Approximately 90%-100% of the adult value.

What is the estimated GFR at 1-2 years of age?

Approximately 100%-120% of the adult value.

At what age are most organ systems considered substantially mature?

Approximately 2 years of age.

When do standard pharmacokinetic and pharmacodynamic principles begin to approximate adult values?

After approximately 2 years of age, when most systems have substantially matured.

What are the primary advantages of oral medication administration in children?

It is common, convenient, generally easiest, and less expensive.

What pediatric oral formulations are listed in the presentation?

Liquids, chewable tablets, sprinkles, and orally disintegrating or melting products.

Which pediatric patients may have difficulty receiving oral medications?

Very young infants, severely ill children, and children with malabsorption.

What device should be used to accurately administer pediatric liquid medications?

An oral syringe.

What formulation characteristics should be considered when prescribing oral medication to a child?

Sugar content, alcohol content, flavor, taste, concentration, and the volume required per dose.

Why is medication palatability important in pediatrics?

Poor taste or excessive volume can reduce adherence.

When may the rectal route be useful in children?

When oral administration is not possible, such as with serious nausea, vomiting, high fever, or inability to swallow.

How should a pediatric suppository be administered?

The entire suppository should be administered at one time.

Should a suppository be divided into two separate administrations?

No. The presentation states not to split it into two administrations.

What may a caregiver need to do after inserting a pediatric suppository?

Hold the child's buttocks closed briefly to prevent the suppository from being expelled.

When should the rectal route generally be reserved?

For patients who cannot take oral medications.

What are the three parenteral routes listed in the presentation?

Intravenous, intramuscular, and subcutaneous.

What is the main advantage of parenteral medication administration?

It is the most reliable route, especially in seriously ill children.

What can be used to reduce pain associated with pediatric injections?

A topical anesthetic.

What is the recommended maximum IM injection volume for children younger than 2 years?

Less than 1 mL.

What adult IM injection volume is cited for comparison?

Approximately 5 mL.

What practical concern may complicate parenteral medication administration in children?

IV line placement or maintenance of reliable vascular access.

What are the two most common expressions used for pediatric weight-based dosing?

mg/kg/day and mg/kg/dose.

What does a dose expressed as mg/kg/day represent?

The total medication amount to be administered during a 24-hour period.

What must be done after calculating an mg/kg/day dose?

Divide the total daily amount by the prescribed number of daily doses.

What does a dose expressed as mg/kg/dose represent?

The amount administered with each individual dose.

Should an mg/kg/dose result be divided again by the number of daily administrations?

No. The calculated result is already the amount for each dose.

What is the most important initial step when calculating a pediatric dose?

Determine whether the order is written as mg/kg/day or mg/kg/dose.

What was the ampicillin dose used in the early-onset sepsis calculation example?

200 mg/kg/day divided every 6 hours.

What was the gentamicin dose used in the early-onset sepsis calculation example?

2.5 mg/kg/dose every 12 hours.

How many doses per day are given when a medication is ordered every 6 hours?

Four doses per day.

How many doses per day are given when a medication is ordered every 12 hours?

Two doses per day.

What is the total daily ampicillin dose for a 25-kg child receiving 200 mg/kg/day?

5,000 mg/day.

What is the individual ampicillin dose when 5,000 mg/day is divided every 6 hours?

1,250 mg every 6 hours.

What is the gentamicin dose for a 25-kg child receiving 2.5 mg/kg/dose?

62.5 mg per dose.

What is the final gentamicin order in the 25-kg example?

Gentamicin 62.5 mg every 12 hours.

What is body-surface-area dosing?

A dosing method based on the patient's body surface area in square meters rather than solely on weight or a fixed dose.

In what therapeutic area is BSA dosing widely used?

Oncology, especially cytotoxic chemotherapy.

Why is BSA dosing used for chemotherapy?

It may better normalize drug exposure across patients of different sizes and reduce variability in pharmacokinetics and toxicity.

What patient measurements are used to estimate BSA?

Height and weight.

What BSA was calculated for the 50-kg, 150-cm patient?

1.44 m².

What cisplatin dose was used in the BSA example?

100 mg/m² per cycle every 4 weeks.

What cisplatin dose is calculated for a patient with a BSA of 1.44 m²?

144 mg per cycle.

What approximate BSA did the nomogram estimate for the 50-kg, 150-cm patient?

Approximately 1.50 m².

What is the least accurate general method of pediatric dosing?

Age-based dosing.

Why is age-based dosing relatively inaccurate?

It assumes that all children are near the 50th percentile of the growth chart.