Week 1 Basics Flashcards
What is pharmacokinetics?
The study of what the body does to the drugs
What is the Acronym to remember the 4 phases of pharmacokinetics?
ADME
What does ADME stand for?
Absorption
Distribution
Metabolism
Elimination
What are the three aspects of absorption?
- Routes of administration
- Methods of Absorption
- Factors that affect absorption
What are the three routes of administration?
- Enteral - Within the GI tract
- Parenteral - IV, IM, Subcutaneous
- Other- Inhalation, transdermal, nasal, thecal, opthalmic, interventricular
What are the three most common methods of absorption?
- Passive
- Active
- pincytosis
What is passive absorption?
Simple diffusion.
Dependent on a concentration gradient
Requires no energy
High concentration to low concentration
What is the most important mechanism for drug absorption?
Passive absorption
What must drugs be in order to utilize passive absorption?
Small, lipid or fat-soluble, non-ionized
Acidic environments favor the non-ionization of ___
Weak acids
Basic environments favor the non-ionization of ___
Weak bases
What is active absorption?
Active transport
Requires energy
Moves particles from a low concentration to a high concentration
opposite of passive absorption
What is pincytosis?
Process that allows cells to carry drugs across their membranes by engulfing the drug particle
What are the three main factors that affect drug absorption?
- Rate of dissolution
- Blood flow
- Contact time
The rate of dissolution determines ____
the rate of absorption
How does blood flow impact absorption?
The more blood flows the more absorption via more drug being available to the tissue that is doing the absorbing.
Which has more blood flow the stomach or the intestines?
The intestines.
How might shock affect drug absorption?
Reduces blood flow to the skin or other absorptive tissues
How does contact time affect the absorption?
The more contact time the more absorption. Vice Versa
Give an example of altered contact time.
Diarrhea causes reduced contact time in the intestines d/t increased gastric motility
What are some other factors that may affect absorption?
Drug-Drug and Drug-food interactions
Various disease processes
What are some factors that may affect the bioavailability of a drug?
Metabolism, surface area, food intake at the time of administration
What is the bioavailability of IV drugs?
100%
What is the bioavailability of non-IV drugs?
Less than 100%