Pharmacokinetics route of administration Flashcards
What does the body do to a drug?
absorption, distrubution, metabolism, elimination (ADME)
True or false: Smaller drugs cross membranes more easily.
true
What can effect molecular weight?
protein binding
What protein typically binds to weak acids and decreases with inflammation?
albumin
What protein typically binds to weak bases and increases with inflammation?
alpha 1 acid glycoproteins
What types of drugs cross membranes easily and distribute widely?
lipophilic
What kinds of drugs are confined to plasma and ECF?
hydrophilic
Do ionized or unionized drugs tend to distribute more widely and why?
unionized because they can cross membranes easier
What is the term at which the pH is at a level where 50% of the drug is ionized and 50% is unionized?
pKa
What can alter a drugs concentration gradient?
dose and route
blood flow (disease can effect this)
What is the method by which most drugs will cross the membrane?
passive diffusion
What can be used when a drug is lacking sufficient lipid solubility for passive diffusion?
carrier-mediated transport
Does carrier mediated facilitated diffusion use ATP?
no it is still going down its concentration gradient
What are the 2 major differences when using active transport?
against concentration gradient and needs ATP
What plays a very important role in absorption of a drug?
route of administration
What are the four major routes of administration?
intravenous, intramuscular, subcutaneous, oral
What method of drug administration completely skips the absorption step?
intravenous- directly into the bloodstream 100% absorption
Why is absorption through the intramuscular route high?
muscles are highly vascular
What can decrease absorption from subcutaneous injections?
moderate to severe dehydration or shock due to less blood flow to the skin
_______ soluble drugs are often absorbed slower, while _______ soluble drugs are often absorbed faster.
lipid, water
What is administration via the GI tract?
enteral
What is the most variable and slowest form of absorption which can be effected by diet?
oral
What can be used to improve absorption?
solubility enhancers
What can cause poor oral bioavailability?
drug is decomposed or complexed in GIT
What is the clinical reference of ion trapping in the stomach?
NSAIDs become trapped in gastric surface cells causing cell death and ulcers
What is the term for when a large amount of drug absorbed is immediately metabolized in the gut or liver prior to absorption into systemic coruscation?
first pass metabolism
Why are drugs with high first pass metabolism often not suitable for PO administration?
they do not reach adequate plasma concentrations
What administration method has rapid uptake of a drug into systemic circulation and avoids first pass metabolism?
transmucosal
What is the method for drugs being absorbed through the skin into circulation?
transdermal
True or false: transdermal and topical are the same.
False: topical stays on top of the skin
What is the term for maximum plasma concentration and typically highest for IV dosing?
Cmax
What is the term for time to maximum plasma concentration?
Tmax
What is the term for percentage of administered drug that appears in the bloodstream after dosing?
bioavailability
True or false: bioavailability can never be > 100%.
true
What is it called when the absorption phase is prolonged?
flip-flop phenomenon
What does live disease effect absorption?
decrease first pass metabolism and increases oral absorption
