*CH 46 Pharmacokinetics & routes administration Flashcards
what is medication Absorption ?
Transmission of medication from location of administration to the blood stream
where does absorption take place?
GI tract, muscle, skin, subcutaneous tissue
What are common routes of administration enteral and parenteral?
Enteral: through GI tract
Parenteral: by injection
unique pattern of absorption ?
rate
amount
route
what are Oral route barriers to absorption
meds must pass through layer of epithelial calls that line GI tract.
oral route Absorption pattern
stability and solubility of meds GI pH and emptying time Food in stomach or intestine current meds form of med: coated, liquid
Subcutaneous and intramuscular barriers to absorption?
Their are none
Subcutaneous and intramuscular absorption pattern?
solubility of medication in water
blood perfusion at the site of injection
what are the two types of solubility of medication in water ?
high soluble meds = rapid absorption (10-30 min)
Poor soluble meds=slow absorption
what are the two blood perfusion types at the site of injection?
high blood perfusion = rapid absorption
low perfusion site = slow absorption
Are their any intravenous barriers to absorption?
no barriers
What are the two intravenous absorption pattern ?
Immediate; enters directly into the blood
Complete: reaches the blood in its entirely
what is the distribution of medication?
is the transportation of medication to the site of action by bodily fluids
What are the factors that influence distrubution?
circulation
permeability of the cell membrane
plasma protein binding
what condition can inhibit blood flow or perfusion
Peripheral vascular disease
cardiac disease
what is the permeability of the cell membrane ?
Meds must pass through tissue and membrane to reach targeted area.
what medication type can cross blood brain barrier and the placenta?
lipid soluble or medication that have transport system
What is plasma protein binding?
- medication compete for protein binding sites within the blood stream primarily albumin.
- 2 meds that compete for same binding site = toxicity
Metabolism (biotransformation)
changes meds into less active forms by action of enzymes.
where does metabolism take place
primarily Liver but also in kidneys, lungs, intestines blood
what are factors that influence med. metabolism rate
age increase in some meds-metabolizing enzymes First past effect similar pathways nutritional status
an increase in some med-metabolism enzymes
can metabolize some meds sooner = increase in dosage to maintain therapeutic level. can increase metabolism in other concurrent use of meds
First pass effect
liver inactivates some meds on first pass.
require nonenteral route (sublingual / IV)
Similar metabolic pathways
same pathways for 2 meds = alteration of 1 or 2 meds = decrease of one or both meds = accumulation
nutritional status
malnourishment=deficient in medication - metabolizing enzymes = NO medication metabolism
what is Excretion of medication?
meds eliminate PRIMARILY through kidneys
liver lungs intestine, exocrine glands (breast)
medication response is
min. effect concentration (MEC & toxic concentration)
plasma medication level
is therapeutic range when it is effective and not toxic
Medication High TI (therapeutic index)
no blood med level monitoring
meds low TI
monitor med levels
Highest plasma level when elimination is
absorption
oral med peak
1-3 hours after given
IV peak
with in 10 min
when should you get trough level ?
blood sample right before meds
Half life
med drops 50%
what affects half life
liver and kidney
how long does it take to achieve steady blood concentration?
four half lives
med intake =
med metabolism & excretion
short life
leaves body in 4-8 hours
short dose interval
drops between doses
long life
leave body slowly
24 hours
greater risk meds accumulation & toxicity
meds given at longer interval
Agonist
drugs that occupy receptor and activate them
ex: morphine
antagonist
medication that can block the usual receptor activity.
ex: losartan
partial agonist
less activation on the receptor
oral (enteral) route
most common
least expensive
convenient
contraindication for oral meds
vomiting decrease GI motility' absence of gag reflex difficulty swallowing decrease level of consciousness
buccal is where?
between the cheek and gum
how to hold ear canal for a young child
down and back
how to hold ear for an adult
upward and outward
nasogastric & gastrostomy tubes nursing action
- Verify tube placement
- flow by gravity or push it in with plunger of syringe
- administer meds seperatley
- completely dissolve crush tablets and capsules content in 15 to 30 mL of water
flush with another 30-60 mL use sterile water for immunocompromised critically ill client
nasogastric & gastrostomy tubes nursing DO NOT action
- administer sublingual meds
- crush specially prepared oral meds
- mix medication
Parenteral best sites?
IM injection of 2mL +
ventrogluteal is preferable site
deltoid site = 1mL
Subcutaneous site
abdomen
upper hip
lateral upper arms
thigh
Intramuscular common sites
ventrogluteal
deltoid
vastus lateralis
