Week 2 Flashcards
Onset of action
The first sign of therapeutic effect on the drug concentration curve.
Peak level
Highest concentration of a drug in the system. Make sure the therapeutic level is reached without being toxic.
Trough level
The lowest concentration of a drug in the system before another dose is given. Important when trying to keep a dose in therapeutic range.
Blood-brain barrier
Has a protective function. Made up of a single layer of epithelial cells, tight junction if epithelial cells. Astrocytes surround capillaries to prevent unwanted molecules from getting from the capillaries into the CSF. to enter the CAF, molecules have to be small, lipid-soluble, lower iconic charge, same pH as CHF.
Fetal placental barrier
Delivers nutrients but protects from pathogens, drugs, and the mother’s immune system. Barrier. Between maternal and fetal blood flow. Has few intercellular. Bridges (cell junctions) which prevents things from passing the barrier. Sugars, fats, I2, antibodies, idea, and CO2 can still pass the barrier.
Renal insufficiency
Can cause a buildup of renally-excreted drugs.
Off-label prescribing
Use of FDA-approved drug in a dose or route for which it was not approved or for a clinical condition other than the FDA-approved use.
Pediatric absorption
Gastric ph does not reach adult level until 1. If an acidic environment is needed for absorption, less will be absorbed by infants.
Greater BSA. Greater absorption of topical meds
Infant skin more permeable. More absorption of topical meds.
Immature peripheral circulation. Prevents absorption of IM or SQ meds.
Pediatric distribution
Differences in body water and fat.
Immature liver function. 0-6 mo less albumin and fewer plasma proteins. Fewer binding sites, so higher concentrations of 2 or more drugs or less affinity for one of them.
Immature blood-brain barrier- not developed at birth, leading to greater risk of CNS toxicity.
Phase 1 Metabolism in pediatrics
CYP3A7:
cytochrome P450. The earliest isoenzyme to show activity. Present in utero and rapidly decreases after birth. Then CYP3A4 and 5 increase after 6 mo.
Pediatric excretion
Neonate or preterm infant has immature kidneys.
Monitor drug doses and therapeutic blood levels to prevent toxicity.
Reduced GFR and decreased tubular secretion and reabsorption during the first 6 months leads to extended 1/2 life.
3 months: kidneys concentrate urine at the adult level, but urinary excretion is low until approximately 30 mo.
FDA pregnancy categories
A: controlled studies in prefers and no risk.
B: animal studies show no risk. No pregnant human studies.
C: animal studies show no risk. No human studies. Benefits might outweigh risks.
D: risk; benefit might outweigh risk in serious situation.
X: demonstrated fetal abnormalities; risk outweighs benefit; should not be used.
Absorption in pregnancy
Progesterone decreases gastric tone and mobility. Prolonged stomach emptying time. Alters pharmacokinetics of oral meds.
Progesterone promotes respiratory changes. Increased tidal volumes, increased pulm vasodilation, inhaled drug absorption increased.
Distribution and metabolism in pregnancy
HR increases 10-15 bpm
50% inc in blood vol causes hemodilution of albumin to potentiate drug distribution.
Plasma lipid levels increase altering drug transport and distribution.
Drugs compete for receptor sites occupied by hormones resulting in more unbound free drug.
Drugs that are not lipophilic enter fetal circulation
Drug metabolism is not affected by pregnancy or lactation.
Distribution during lactation
Drugs with increased lipid solubility and low protein binding such as CNS agents pass easily into breast milk.
Drugs of low molecular weight pass into milk
Low pH produce high concentrations
