Module 2 Flashcards
Study of drug movement in the body.
Pharmacokinetics
Movement of the drug from the site of administration into the blood.
Absorption
What does the rate of absorption determine?
What does the amount of drug absorption determine?
Rate of absorption - determines onset of action (i.e. how quickly the drug effect will occur)
Amount absorbed –> determines intensity of the drug effect
What are the different factors affecting absorption?
Rate of dissolution Surface area Blood flow Lipid solubility pH partitioning Activity of drug transport proteins
Dissolving in solution
Dissolution
How is an orally administered tablet dissolved?
The orally administered drug dissolves into the gastric fluid, and can then be absorbed
How does dissolution rate affect onset of action?
Drugs with a faster dissolution rate will have a faster onset of action.
What is the major determinant of drug absorption?
Surface area
How is surface area related to drug absorption?
The higher the surface area, the greater the drug absorption
What increases surface area in the stomach?
What increases surface area in the small intestine?
The stomach has folds called rugae
The small intestine has projections called villi (and microvilli)
How does blood flow drive absorption?
Areas with high blood flow maintain a concentration gradient, driving absorption
How does exercise affect blood flow?
What pathologies decrease blood flow?
Exercise increases blood flow
Blood flow is decreased in heart failure, severe hypotension, hypothermia and circulatory shock
How does lipid solubility affect absorption?
Lipid soluble drugs are absorbed more rapidly than water soluble drugs.
How does pH partitioning affect drug absorption?
Drug absorption is greater when there’s a difference between the pH at the site of administration and the blood, such that the drug is ionized in the blood
How can drug transport proteins increase drug absorption? Decrease?
Uptake transporters increase drug absorption; efflux transporters decrease drug absorptoin
What are the 8 major routes of drug administration?
Oral, rectal, sublingual, transdermal, IV, SC, IM, pulmonaryh
What is the most important and most common route of administration?
PO = per os = oral
Routes of administration that involve the GI tract
enteral
Routes of administration that do not involve the GI tract.
Parenteral
Place the 8 major routes of administration into groups based on whether they are enteral, parenteral or other.
Enteral - oral, rectal
Parenteral - IV, SC, IM
Other - pulmonary, transdermal, sublingual
What are the advantages of oral administration?
Safe, convenient, economic
What are the disadvantages of oral administration.
incomplete and variable absorption