Pharmacokinetics Flashcards
What happens if there is a change in drug plasma concentration
Change in concentration of drug at the site of action
What is plasm concentration important in
Delivery tissues/organs
Removal of drug and drug metabolites
4 key factors in pharmacokinetics
Absorption
Distribution
Excretion
Advantages of IV route
Rapid onset of action
Controlled rate of administration
Avoids GI tract andFirst pass metabolism
Disadvantage of IV route
Requires trained personnel and sterile technique
Advantages of IM/SC route
Rapid onset of action
Controlled rate of administration
Avoids GI tract
Can be performed by patient (insulin)
Disadvantages of IM/SC route
Trained personnel and sterility
Can be painful
Advantages of oral route
Convenient
Disadvantage of oral route
Some drugs are poorly absorbed through the gut wall
Some may be denatured by acid/ enzymes in the stomach
Form complexes with food
Advantages of inhalation route
Rapid onset of action
Avoids first pass metabolism
Disadvantage of inhalation route
Not all drugs can be formulated for inhalation
Advantages of rectal route
Allows targeting of large bowel
Disadvantage of rectal route
Variable absorption and patient acceptability
Enteral
Drug entering body by gastrointestinal tract
Bioavailability
Proportion of an administered drug that reaches systemic circulation and is available for distribution to intended site of action
First pass metabolism
Gut to liver
What drug concentrations are required for the desired clinical effect
Enough to be effective but not toxic
At what rate (administration) must the drug reach the systemic circulation to maintain a desired circulation
Depends on dosing schedules and what is practical for the drug and patient
Pharmacokinetic parameters= half life, rate constant, clearance of drug
How long should one dose follow another
Depends on elimination route
Appropriate measure of successful administration of a drug
Clinical effect- measure blood pressure/ glucose levels
Therapeutic drug monitoring services?
Clinical response
Therapeutic range of concentration must be known
