Peds Pharm Flashcards
What are the ages for the following terms: Preterm/premature Neonate Infant Child Adolescent
Preterm/premature: less than 36 weeks gestational age Neonate: Frist 30 days of life Infant:1 month to 1 year Child: 1-12 years Adolescent:12-18 years
Variables affect GI absorption how
- pH
- Gastric emptying time
- Pancreatic enzyme activity
- GI surface area
- Intestinal microorganisms
- pH
- -more alkaline than adults until child reaches 1 year
- -adversely affects the absorption of weakly acid drugs and improves the absorption of weakly basic drugs
- gastric emptying time and GI motility
- -slower than adults for the first month of life
- -neonates and infants have irregular peristalsis
- Pancreatic enzyme activity
- -decreased in first year
- -affects drugs that are fat soluble (neonates cant absorb vitamin E)
- GI surface area
- -In young children the relative size of the duodenum compared with the adults enhances drug absorption
- Intestinal microorganisms
- -Intestinal flora depends more on diet than age
- -more rapid development of flora in breast fed infants
- -flora is active in the breakdown of various drugs
Rectal absorption
- Used in who
- drug is absorbed how
- Problems with this method
Used in who
-those that cannot tolerate oral drugs or lack of IV access
drug is absorbed how
-by the hemorrhoidal veins and avoids first pass metabolism
Problems with this method
- drugs are erratically and incompletely absorbed
- babies dont have good sphincter tone so the meds could come right back out
IM absorption
- affected by
- quality of absorption in neonates
- quality of absorption in infants
Affected by
-muscle mass, blood flow to the muscle, tone, activity
Neonates
-Erratic and poor absorption d/t decreased muscle mass and activity and tone
Infants
-greater density of skeletal muscle capillaries than older children therefore more efficient absorption
Percutaneous absorption
- affected by
- quality of absorption in neonates
Affected by:
- thickness of the skin
- body surface area relative to body mass
Neonates:
-have thin skin and increased body surface area relative to body mass, leading to significant drug absorption in neonates compared to adults
Factors affecting distribution in pediatric patients (6)
- vascular perfusion
- body composition
- tissue binding characteristics
- physiochemical properties if the drug
- plasma protein binding
- route of administration
Distribution: Vascular perfusion
-Are changes in perfusion common in neonates?
Ex
Changes in perfusion are common in neonates
Ex. in response to hypoxia, the blood mat be diverted (shunted) from the lungs to the tissues and organs. This could be a problem if we are trying to give an inhaled medication
Distribution: Body composition
- What happens to the volume of distribution if total body water and extracellular water increase?
- Explain how this applies to neonates
- The higher the total body water and extracellular water, the larger the volume of distribution
- neonates and infants have increased total body water and ECF compared to older children and adults, so some drugs will require a larger dose per Kg in infants and younger compared to adults…think of it being more diluted (neonates are just little bags of water)
Distribution: Tissue Binding Characteristics
-what happens to free blood levels of a drug when the mass of tissue is reduced?
Drugs bound to tissues exhibit increased free blood level when the mass of tissue is reduced such as in pediatrics
Distribution: Physiochemical properties
-What properties affect the ability of the drug to move across membranes into target tissues and cells?
- lipid solubility
- molecular configuration
Distribution: Plasma protein binding
- How is neonate protein levels different from adults?
- what does this result in?
- how does this affect neonate VD?
Neonates have:
- decreased Alpha1-acid glycoprotein (binds alkaline drugs)
- decreased albumin (bind drugs, fatty acids, and bilirubin)
This results in drug displacement and increased plasma levels due to decreased availability protein for binding
This means neonates have a larger volume of distribution compared to adults
Distribution: Route of Administration
primary distribution site for:
-Orally
-IV
Orally
- liver becomes the primary distribution site
- affected by hepatic first pass metabolism
IV
-heart and lungs act as the primary method of distribtuion
How is ECF different in neonates vs adults?
Neonates have about 40% of their body wieght as ECF while adults have about 20% of their body weight as ECF.
*Volume of distribution should reflect the ECF compartment of the patient
(volume of distribution-the more water there is, the more dilute the drug is going to be)
What drugs have increased VD in neonates?
increased uptake and VD?
Increased VD in neonates
- theophylline
- ampicillin
- phenobarbitol
- phenytoin
Increased uptake and VD
- morphine
- fentanyl
- digoxin
Is drug metabolism delayed in neonates, infants, and young children?
What is drug clearance reliant on?
Yes!
Drug clearance is reliant on hepatic metabolism
What are the phases of drug metabolism in neonates, infants, and young children?
Phase I (oxidation, reduction, hydrolysis)
- CYP 450 system
- decreased in neonates
- need smaller doses and less frequent dosing)
- increased in infants and children
Phase II (conjugation) -acetaminophen normally is metabolized via gluconidation but neonates and infants dont have this ability so broken down by sulfate conjugation
What is the half life of acetaminophen in neonates? Adults?
neonates: 3.5 hours
Adults: 2 hours
What are the consequences of neonates and young children having an immature renal system?
- decreased plasma clearance of many drugs via the kidneys
- decreased tubular secretion and reabsorption rates
- proximal tubules decreased ability to concentrate urine
What antibiotics have longer half lives in neonates die to decreased renal excretion?
- PCN
- Sulfonamides
- Aminoglycosides
What are two common overdoses in young children?
- Iron supplements (contained in some childrens vitamins)
- Acetaminophen
Infants and children generally absorb medications more _____ and _____ than adults
Infants and children generally absorb medications more rapidly and completely than adults
What are two drugs to avoid in pediatric patients?
- Propylene glycol
- -added to many injectable drugs to increase stability)
- -may cause hyperosmolality in infants
- Benzyl alcohol
- -preservative in IV fluids
- -can cause metabolic acidosis, neurologic damage in neonates
Cystic Fibrosis pts have increased requirements and increased clearance of what drugs?
- aminoglycosides
- PCN
- theophylline
What GI disorders may requires dose adjustments and why?
- celiac disease
- gasteroenteritis
- severe malabsorption
-because these disease will affect the absorption of the drug
