Principle Concepts Flashcards
Therapeutic Range
Plasma concentration at which a drug exerts its desired effect
Dosage Regimen
●The amount, route, frequency, and duration of drug administration
●Determines the amount of drug being administered to an animal, based on:
1. Dose
2. Dosage interval
Route of Administration
●Drugs must be administered in a form and by a route that will allow them to reach their target site in the body
–Topical
–Oral
–Inhalation
–Parenteral
Pharmacokinetics
Sequence of events that occur once a drug is administered
1. Drug Absorption: Drug is absorbed into the bloodstream
2. Drug Distribution: After absorption there is distribution to body fluids and tissues, including target tissue
3. Drug Metabolism: The body begins to break down (metabolism)
4. Drug Elimination: excrete the drug immediately after absorption
Define: Drug Absorption
●Movement of drug from administration site into systemic circulation
Define: Bioavailability
degree to which drug is absorbed and reaches systemic circulation
Hydrophilic
(ionized) molecules that diffuse through the fluid that is between cells
Lipophilic
non-ionized molecules that diffuse across the cellular membrane
Define: Drug Form
Solid drug forms must be broken down to smaller particles before absorption therefore delaying absorption
Drug Distribution
●Once in the systemic circulation drug must be distributed to target tissues
●Initial distribution is to highly perfused tissue such as the brain/vital organs
●Drugs enter target tissue at capillary level
The “rights” of proper drug administration:
• Right drug
• Right dose
• Right route
• Right time
• Right patient
• Right documentation
Define: Dose
amount of drug administered at one time
Define: Loading dose
initial dose of drug given to get the drug concentration up to therapeutic range in a short period of time
Define: Maintenance dose
the dose of drug that maintains or keeps the drug at therapeutic levels.
Pharmacokinetics includes?
- Drug Absorption
- Drug Distribution
- Drug Metabolism
- Drug Elimination
Drug Absorption is affected by?
Affected by
route of administration
drug’s hydrophilic/lipophilic nature
drug form
GI tract condition
Liver metabolism after GI absorption
Blood perfusion at administration site
Polarity affects a drug molecules ability to move across physical barriers
◦ Greatly affected by the PH of the body
Hydrophilic can be given?
SQ
Lipophilic can be given?
PO
the First Pass Effect
Some drugs can be completely metabolized by the liver which stops the drug from reaching the heart and other body tissues.
Example: Diazepam (Seizure med) - This is why its given IV so it will go straight to the heart & than to the brain and does not get completely absorbed by the liver.
• Blood Perfusion at the Injection Site
◦ This essentially means if you inject in the same location multiple times than the skin will begin to scar therefore decreasing blood flow
Drug Distribution refers to?
• Once in the systemic circulation drug must be distributed to target tissues which are the highly perfused/vascular tissues/organs:
target tissues are?
◦ Brain, Heart, Lungs, all visceral organs (Abdominal organs), muscle, & last the skin
Drugs can enter target tissue at the?
capillary levels
Blood Brain Barrier
◦ Central Nervous System has specialized capillaries that do not allow protein bound drug molecules through
◦ Prostate, Eyes & Placenta have these specialized capillaries as well.
