Pharmacology Flashcards
Variables Affecting GI Absorption
pH Gastric emptying time GI motility Pancreatic enzyme activity GI surface area Intestinal microorganisms
pH and GI Absorption
More alkaline than adults
Decrease absorption of weakly acidic drugs
Increase absorption of weakly basic drugs
Gastric Emptying Time/GI Motility and GI Absorption
Slower than adults
Irregular peristalsis
Pancreatic Enzyme Activity and GI Absorption
Decreased for first year of life
Affects drugs that are fat soluble
GI Surface Area and GI Absorption
Intestinal size vs. body size
Enhances drug absorption
GI Microorganisms and GI Absorption
Intestinal flora depends on diet
More rapid development of flora in breast fed infants
Flora active in breakdown of drugs
Rectal Absorption and GI Absorption
Cannot tolerate oral drugs/lack IV access
Absorbed by hemorrhoidal veins
Erratically & incompletely absorbed
IM Absorption Affected by:
Muscle mass
Blood flow to muscle
Tone
Activity
IM Absorption in Neonates
Decreased muscle mass
Decreased blood flow
Erractic/poor drug absorption
IM Absorption in Infants
Greater density of skeletal muscle capillaries
Efficient absorption
Percutaneous Absorption Affected by:
Thickness of skin
Body surface area to body mass
Thin Skin + Increased Body Surface Area =
Significant percutaneous drug absorption
Watch for toxicity
Factors Affecting Distribution in Pediatric Patients
Vascular perfusion Body composition Tissue binding characteristics Physiochemical properties of the drug Plasma protein binding Route of administration
Vascular Perfusion in Distribution
Changes in perfusion common
Body Composition in Distribution
Higher body water & ECF the larger the volume of distribution
Some drugs need larger doses/kg
Tissue Binding Characteristics in Distribution
Drugs bound to tissues exhibit increased free blood levels when the mass of tissues i reduced
Physiochemical Properties in Distribution
Lipid solubility
Molecular configuration
Plasma Protein Binding in Distribution
Decreased alpha1-acid glycoprotein
Decreased albumin
Increased plasma levels of drugs
Larger volume of distribution in neonates
Routes of Administration
Orally
IV
IM
Oral Route of Administration
Liver primary distribution site
Hepatic first pass metabolism
Oral doses higher than IV doses
IV Route of Administration
Heart and lungs primary method of distribution
Increased Volume of Distribution of Protein Binding Drugs
Theophylline
Ampicillin
Phenobarbital
Phenytoin
Increased Uptake and Volume of Distribution of Tissue Uptake
Morphine
Fentanyl
Digoxin
What is delayed in neonates, infants, and young children?
Drug metabolism
Plasma clearance of drugs
GFR of Neonates Compared to Adults
Decreased until age 2
Decreased GFR Leads to:
Decreased tubular secretion & reabsorption rates
Proximal tubule decreased ability to concentrate urine
What are some common overdoses in children?
Iron supplements
Acetaminophen
GI and IM Absorption in Pediatric Patients
Infants & children absorb medications more rapidly & completely
Younger the human, more permeable the skin
Readily eliminate meds that are cleared renally
Drugs to Avoid in Pediatric Patients
Propylene glycol
Benzyl alcohol
Factors Affecting Pediatric Therapy
Liver disease
Renal disease
Cystic Fibrosis
GI disorders
Liver & Renal Disease Factors
Avoid hepatotoxic drugs
Avoid nephrotoxic drugs
Patients with Cystic Fibrosis Require Increased Amounts & Increased Clearance of These Drugs
Aminoglycosides
Penicillins
Theophylline
GI Disorders that may Require Dosage Adjustments
Celiac disease
Gastroenteritis
Severe malabsorption
How is Antibiotic Dosing Done in Pediatrics?
mg/kg format
Equation to determine amount of mL
(Desired dose x volume of suspension) / concentration
Tylenol Dosing
10-15 mg/kg q 4-6 hours
Ibuprofen Dosing
5-10 mg/kg per dose q6 hours
Two Major Drug Classes to NOT Use in a Pediatric Population
Fluoroquinolone’s
Tetracycline’s
Why can you not use fluoroquinolone’s in a pediatric population?
Not studied in children
Why can you not use tetracycline’s in a pediatric population?
Black teeth
Osteomyelitis
