Week 1 pharmacokinetics Flashcards
What the body does to the drug
Pharmacokinetics
What are pharmacokinetics
What the body does to the drug
body’s impact on the drug (absorption, distribution, metabolism)
What are pharmacodynamics
What the drug does to the body (actions of the drug on the body, like MOA and physiological changes)
4 processes of Pharmacokinetics
ADME (Absorption, distribution, metabolism, elimination)
These are also called biodisposition
What are Cmax and Tmax
Cmax is max amount of concentration in the body, Tmax is time to reach maximum concentration (peak effect, but depending on when the drug works. May take time (i,e, antidepressants).
Which drug ROA reaches Cmax the fastest
IV (one time IV push)
Which drug ROA reaches Cmax the slowest
Oral (PO)
Oral meds have delayed peak because need to be absorbed in GI tract
What is bioavailability
the total amount of the drug that gets absorbed into the bloodstream compared to if it was given IV (which is 100% bioavailability)
If a drug is very susceptible to first-pass metabolism, what happens to oral bioavailability
Decreases significantly/greatly reduced– it is metabolized and not as high of bioavailability, so should give a different way (rectally, sublingually, since those don’t feed into portal vein)
What is the role and significance of P-gp
Protective protein, expells drug molecules into extracellular space
Multi-drug resistant protein ( MDR-1) to prevent drugs from being metabolized (trying to protect body from invader)
Where is P-gp found
mucosa of GI tract (prevent absorption)
Liver, pancrease, kidney, cancer cells
Do P-gp inhibitors increase or decrease bioavailability
Increase bioavailability (decrease expulsion)
Do P-gp inducers increase or decrease bioavailability
Decrease (expels drug more)
If something is a P-gp inducer, what occurs to P-gp substrate absorption
Decreases p-gp substrate absorption
If something is a P-gp inhibitor, what occurs to P-gp substrate absorption
Increase P-gp substrate absorption
What is transdermal administration
A patch (i.e. nicotine patches)
Have a slow onset of action
Systemic route of administration
What are systemic routes of administration
Oral
Sublingual
IM (IM/SQ)
Rectal( PR)
Transdermal
What are targeted routes of administration
Inhalation
Topical
Opthalmic (i.e. eye drops)
Intranasal
Intrathecal (next to spine, like epidural)
What is biotransformation more commonly known as
metabolism
What ar eprodrugs
inactive parent form of drug that is activated during metabolism
What are active metabolites
When liver metabolizes drugs, creates metabolites, and these metabolites are active (still exert clinical effects). So, both drug and their metabolites have impact ( active metabolites can live longer than parent drug)
What is the overall, main goal of biotransformation
make the drug hydrophilic–> want to be more lipophilic, make it more likely to cross membranes and less likely to be excreted so that can keep making affects
Phase 1 vs phase 2 reactions
1- oxidation, hydrolysis, or reduction
2- conjugation (add polarity like acetate, sulfate, glucuronate)
Which pharmacokinetic enzyme is in half of drug interactions in biotransformation
Phase 1 enzyme CYP 3A4 or 3A5 (Cytochrome P enzyme)
Grapefruit juice inhibits this
What phase are CYP enzymes responsible for
responsible for most drug metabolism oxidation (Phase 1 reactions)
Where are CYP enzymes
Hepatocytes (in liver)
Which enzymes does smoking induce
CYP 1A2 and 2B6 (metabolizes drugs like antidepressants and antipsychotics)
So, if stop smoking, need less of the drug for the same effect
What is half life inversely porportional to
INVERSELY porportional to clearance
Fast clearance, short half life
If a drug has a fast clearance, what is its half life
Short (INVERSELY porportional to clearance
Fast clearance, short half life
If a drug has a slow clearance, what is its half life
Long (INVERSELY porportional to clearance
Slow clearance, Long half life
What is half life directly porportional to
Vd
Large Vd is long half life
How many half lives is steady state reached after
4 (depends on Vd and CL)
What is your peak level
the highest concentration of drug achieved upon giving repeat doses
What is your trough level
Lowest drug concentration achieved upon giving repeat doses
Should be min effective concentration ( still maintianing effect)
What is the random level
Not trough or peak, just a sample of medication level when not at peak or trough
What is the theraputic index
The level that is effective to give drug impact, between toxic concentration and minimum effective concentration.
What is a loading dose
Single dose needed to achieve desired plasma concentration ( steady state)
What is a maintenance dose
Doses given at regular intervals to maintain a target plasma concentration (repleat what is being actively cleared by body)
What is purpose of loading dose
get to steady state faster rather than using maitnence doses.
