Pharmacokinetics Flashcards
What questions should come to mind when thinking pharmacokinetics?
how does the drug get into the body and where does it go?
what does the body do to/ with the drug?
how does the body get rid of the drug?
what is the process of pharmacokinetics through the body?
Absorption
Distribution
Metabolism
Excretion
What is absorption?
the movement of a drug from its site of administration into the body
What is the rate?
how soon will the effects of the drug take place
What is amount?
how intense the effects of the drug will be
What factors affect the process of absorption?
select all that apply
- rate of dissolution
- surface area
- blood flow
- lipid solubility
- pH partitioning
- route of administration
- GI tract
rate of dissolution
surface area
blood flow
lipid solubility
pH partitioning
route of administration
What are the 2 major groups in routes of administration?
Enteral (GI tract)
- oral
Parenteral (outside the GI tract)
- IV
- subQ
- IM
Oral (PO) per os
barriers to absorption
absorption pattern
barriers to absorption
- epithelial lining of GI tract
- capillary wall
Absorption pattern
- slow and variable
what are the advantages and disadvantages of PO
advantages
- safer than injection routes
- ideal for self administration
- easy convenient inexpensive
disadvantages
- can cause GI irritation
- requires cooperative patient
- inactivation
- variability
IV
Barriers to absorption
Absorption pattern
barriers to absorption
- none
absorption pattern
- instantaneous and complete
what are advantages and disadvantages of IV?
advantages
- rapid onset
- control
- permits use of large fluid volumes
- permits use of irritant drugs
disadvantages
- high cost, difficult, inconvenience
- irreversibility
- infection
- high risk
IM and subQ
Barriers to absorption
Absorption pattern
barriers to absorption
- none
absorption pattern
- variable
- water solubility
- blood flow
what are the advantages and disadvantages of IM and subQ?
advantages
- can be used for poorly soluble drugs
- can be used for depot preperations
disadvantages
- discomfort
- inconvenience
- can cause muscke and nerve injury with improper technique
- bleeding risk
When parenteral administration is preferred
Emergencies -> Situations requiring tight control ->
Gi compatibility ( destruction of drugs by GI system, drugs that would cause GI injury ) -> treatment with drugs that cant cross membranes ->
condition better treated with long-acting preparation ->
patients who can’t or won’t take oral preparations
what is distribution
the movement of drugs throughout the body
what is the distrubution process
blood flow to tissues
drugs ability to exit the vascular system
drugs ability to enter cells
what is drug metabolism
the enzymatic alteration of drug structure to a more water soluble form that can be excreted
special factors or considerations in drug metabolism. stuff thatll mess it up
age
first pass effect
nutritional status
competition between drugs
what is excretion
the removal of drugs from the body
drugs and their metabolites can exit the body through?
bile
urine/ feces
sweat/ saliva
breast milk
expired air
monitoring of drug responses
plasma drug levels
2 imp levels
therapeutic range
drug half life
repeated dosing
plasma drug levels
correlation between response to drug and levelin plasma
2 important levels
minimum effective concentration (MEC)
toxic concentration
therapeutic range
determines whether the drug can be safely given
