Unit 1 Flashcards
Define Therapeutic Window.
The difference in plasma concentration [Cp] between the desired and adverse
response MEC
Define Steady State
When the rate of drug administration [RATE IN] equals the rate of drug elimination [RATE OUT]
Pharmacodynamics
What the drug does to the body
Define Bioavailability
The fraction of unchanged drug reaching the systemic circulation following administration by
any route.
AKA transfer of drug from site of adminstration –> blood
What is volume distribution?
The drug dose needed for desired plasma concentration
Define distribution
movement of drug from blood stream into tissue
What is the major organism for metabolism?
The liver
What is the major organism for excretion?
The kidney
Four factors influencing drug membrane passage
- Molecular size - can be affected by drug binding to plasma proteins
- Lipid solubility - estimated by oil:water partition coefficient
- Degree of ionization - affected by tissue pH, will influence lipid solubility
- Concentration gradient - created at site of administration
What size molecules can diffuse through aqueous channels?
100-200 MW
What is the major method of diffusion for drugs with molecular weight 500-800?
lipid diffusion
Formula for bioavailability?
Area under the curve (AUC) via any route (usually oral)
______________________________________
Area under the curve intravenous
What is another term for bioavailability?
Extent of absorption
Two main factors that dictate the plasma concentration?
- Rate (time to peak)
2. Extent (Bioavailability)
What is first pass effect?
When the drug concentration is greatly reduced due to liver metabolism or gastric metabolism
Define rate of absorption
the peak concentration plasma or the time to attain peak plasma concentration
Enteric coating
fatty acids applied to oral medication to protect medication from the stomach.
protects drug from the stomach acidity and can only be broken down in the small intestines (more basic environment)
parenteral route
any drug that is NOT administered via the gastrointestinal tract
A generic drug formulation is said to be bioequivalent to a brand name drug formulation if:
- Rate (estimated by maximum of peak drug concentration [Cmax]) and extent (bioavailability) that the active ingredient drug is absorbed and becomes available at the site of action (drug entering systemic circulation) is similar (within set limits) to the brand name product
- Drugs are considered bioequivalent if the 90% confidence interval of the mean AUC and
the mean Cmax of the generic product (T-test) is within 80-125% of the brand product
What are two main things to considered when choosing drug route adminstration?
bioavailability and relative rate of onset
Example of enteral routes of administration?
Oral and rectal
Is the rate of absorption higher in the stomach or the small intestines?
Small intestines because it has larger surface area!
Benefits of using IV drugs?
most accurate and rapid onset (
How would you administer a drug that has a limited therapeutic window?
Use an IV