PHARMACOKINETICS AND DRUG ADM TERMS PART A Flashcards
tablets, capsules, liquids
oral solids and oral liquids
safety coated
enteric coated
administered under the tongue for systemic effect
nitroglycerin
sublingual
drug placed between gum and cheeks
nicotine gum
buccal
most tablets/capsules
releases drug as quickly as possible after administration
onset of action in minutes to hours
immediate release (IR)
delayed release
controlled release
extended release
sustained release
modified release formulation
drug released over a sustained period
not at a constant rate
variable plasma concentration
sustained release
maintains drug release over a sustained period at a nearly constant rate
consistent plasma concentration
controlled release
drug is released only at some point after the administration
enteric coated tablets, colorectal drugs
modified release formulations
slow uniform absorption of drug over 8h or longer; longer therapeutic effect
dose dumping
extended release
pros
useful for local/systemic drug effects in patients unable to tolerate oral administration
cons
unpredictable absorption, patient compliance, irritation
rectal route
pros
useful for local delivery and
reduces drug exposure and systemic side effects
small doses and large area of absorption
cons
irritating, dose limitations, time-consuming
inhalation
homogenous mixture
most common
for water soluble drugs
IV,IM, SQ
solutions
heterogenous mixture
increases stability for insoluble drugs or chemicals
provides slower release from injection
SQ or IM
parenteral formulations
for water insoluble drugs
oil in water or water in oil
reduces irritative chemicals
increases stability
emulsions
used to store unstable drugs
lyophilized into powder
dry powders
injection into the layer of skin just below the dermis and epidermis
subcutaneous admin
typical sites are delta, ventrogluteal, vastus laterals, dorsogluteal
intramuscular admin
methyprednisolone, triamcinolone, dexamethasone, hydrocortisone
corticosteroids
lidocaine, bupivacaine
intra-articular
skin testing, allergy design, TB testing
very small amounts 0.1 mL
intradermal
bypasses the blood brain barrier and blood CSF
used for spinal anesthesia (subarachnoid, brain tumors, CNS infections)
intrathecal
epidural space around spinal cord
epidural
injection into base of penis
intracavernous
applied to skin or mucous membranes
local effect
absorption is slow and unpredictable
creams, ointments, gels, lotions
systemic absorption controlled release mechanisms used in place of oral avoids first pass metabolism available as multi-day therapy small molecules affected by pressure and temp irritating
transdermal patches
the movement of a drug from its site of administration into the central compartment
absorption
the fraction of unchanged drug reaching systemic circulation following administration by any route
- iv administration
- other routes may be <100%
bioavailability
main route of transmembrane movement for most drugs
drug molecule penetrate by diffusion along a concentration gradient
lipid-soluble drugs diffuse most rapidly across the membrane
passive diffusion
ion trapping: acidic drug will accumulate on the more basic side of the membrane and a basic drug on the more acidic side
influence of pH on ionizable drugs
requires energy to move solutes against an electrochemical gradient
-Na/K ATPase
active transport
transport of solutes in between cells
tight junctions limit this type of movement
paracellular transport
rate of diffusion away from the site of administration is directly proportional to the concentration
concentration
dissolution of the tablet, interactions among the various ingredients
physical state of formulation and dissolution rate
increases drug degradation since PCN is sensitive to stomach acid
penicillin
more time in the stomach may cause gastric irritation
aspirin
absorption is the most rapid from highly vascular tissues
intramuscular injection: deltoid vs gluteus maximus
muscle vs fat
vascularity and blood flow
to cross the plasma membrane
lipid solubility
- well perfused organs receive the most drug initially
- delivery to muscle, most viscera, skin and fat is slower
organ perfusion/blood flow
determines the concentration gradient between blood and the organ
skeletal muscle has a larger capacity than the brain
size of the organ
organs with high lipid content will dissolve a high concentration of lipid soluble agents rapidly
solubility
binding of a drug to macromolecules in the blood or a tissue compartment increase the drug concentration in that compartment
binding
relates the amount of drug in the body to the concentration of drug in blood
volume of distribution
movement of drugs between the central compartment and the peripheral compartment
two-compartment model
plasma concentration is highest immediately after the IV bolus but then rapidly decreases the drug distributes into the peripheral compartment
distribution phase
after a distribution reaches equilibrium, plasma concentration decreases at a constant rate
elimination phase
thiopental?
a general anesthetic
what are the types of plasma proteins?
albumin
alpha 1 acid glycoprotein
this plasma protein binds acidic drugs
albumin
this plasma protein binds basic drugs
alpha 1 acid glycoprotein
only free drug that exerts a biologic effect
protein binding and drug action
fraction of bound drug determined by?
drug concentration
affinity of binding sites
number of binding sites
condition and diseases that affect protein binding?
hypoalbuminemia
acute phase reactions responses increase alpha 1 acid glycoprotein
many drugs accumulate in tissues and generally reversible
tissue binding
drugs that accumulate
- tetracycline
- heavy metals
bone
stores lipid soluble drugs
low blood flow to fat makes it a stable reservoir for drug
patient variability
fat
product of metabolism which has pharmacologic effect
may have weaker or stronger effects than the parent compound
example
-morphine to morphine-6-glucuronide and normophine; both active
active metabolites
product of metabolism without pharmacologic effect
inactive metabolites
metabolite with harmful properties like morphine to morphine-3-glucuronide
toxic metabolites
metabolism of a this produces the active metabolite
i.e.- heroin
prodrug
metabolism of the drug prepares it for elimination
elimination
the volume of plasma that is filtered of drug per unit time
clearance
