Week 9: Pharmacokinetics highlights Flashcards
List/ explain the Pharmacokinetic Principles
LADME
Liberation: Release of the drug from dosage form
Absorption: Movement of drug into circulation
Distribution: Diffusion of drug into body tissues
Metabolism: Conversion to inactive form (usually via liver)
Excretion
Differentiate between the 2 main types of pharmacokinetics
1) First-order (linear) kinetics: a constantfraction(most drugs)
2) Zero-order (nonlinear): a constant amount
How can you remember the difference between first-order and zero-order kinetics?
First order is a fraction
1) Define half-life
2) Define steady state
3) What is the 5 half-life rule?
1) Time req. for a drug amt to be reduced by 50%
2) Drug concentration in the body stays constant
3) 5 half-lives to reach steady state, 5 half lives for elimination
Drugs of abuse tend to have a ___________ half life
shorter
1) What is therapeutic drug monitoring measuring? (TDM)
2) How is it usually measured?
1) Measuring the concentration of a drug or its metabolite
2) Trough or peak levels
Give a few indications for therapeutic drug monitoring (TDM)
1) Narrow therapeutic index
2) Pt compliance
3) Drug toxicity
4) Significant pharmacokinetic variability
1) What is the goal of DAT testing?
2) In pain management: _________ test can be due to not taking drug as prescribed
1) qualitative results (present vs absent)
2) negative
Define drugs of abuse testing (DAT)
Testing for use of illicit drugs and potentially addictive or harmful therapeutic agents
Initial screening DATs are ___________ but often less ____________ (many common false __________ from medications, etc.)
sensitive; specific; positives
True or false: DAT does not detect every possible drug that the patient may have ingested.
True
Single test detects only fairly ________ use
recent
Why are DAT tests qualitative and not quantitative?
Does not determine degree of impairment, dose/frequency of drug taken, exact time of drug use, etc.
Decongestants can make you test positive for what?
Amphetamines
What test is highly specific?
Cocaine metabolite
What may cause you to test positive for opioids?
Quinolones
What 2 things can make you test positive for phencyclidine?
Dextromethorphan and diphenhydramine
Examples of Important Environmental Toxin Poisonings
1) Carbon monoxide (CO): carboxyhemoglobin (COHb) using using blood gas co-охimеtry
2) Lead
3) Insecticides (organophosphates): serum cholinesterase enzyme activity
