Exam 3 General Info Flashcards
What is onset?
The time form when a drug is introduced into the body to when it begins to show a therapeutic effect
What is duration?
The total time where a drug is displaying a therapeutic effect
What is intensity?
The Cmax of the drug or a point in time where the drug is displaying the greatest amount of effect
What are reasons why less than 100% of a drug may not reach the site of action.
Excretion and Degradation
Define pharmacokinetics
The study of absorption, distribution, biotransformation, and elimination of xenobiotics
Define pharmacodynamics
The study of molecular, biochemical, and physiologic effects of xenobiotics and their mechanisms of action.
Biopharmaceutics is…..
The pathway of the drug from the mouth all the way until it gets absorbed
What is drug disposition?
The fate of a drug after it has entered the systemic circulation
What do pathophysiology, pharmacodynamics and pharmacokinetics add up to?
Pharmacotherapeutics
What percent of drugs currently fail clinical trails due to problems with ADME
Less than 10%
Which route of administration will give the most rapid effect based on onset
Intravenously - entered the bloodstream and can bypass physiological barriers
Which route of administration will give the least amount of onset? (usually)
Orally - has to go through many physiological barriers before causing an effect
What is special about intramuscular dosing?
Can be specially made to have a very long lasting duration
The 4 major routes of administration are?
Ingestion (orally)
Inhalation (pretty quick)
Dermal (hard to administer drugs this way)
Parenteral (injections such as intravenous, subcutaneous, intramuscular, intraperitoneal)
A reduction in the extent of absorption will impact which pharmacological effect?
Intensity (but it may also effect the others)
A reduction in the speed of entry will impact which pharmacological effect?
Onset
Whats the difference between fexofenadine and diphenhydramine?
diphenhydramine can cause drowsiness while fexofenadine has an added structure which provides the same effect but it dose not provide sleepiness.
What are the four potential consequences of drug metabolism (biotransformation)?
- Active drug to inactive metabolite (phenobarbital - hydroxylation - hydoxyphenobarbital)
- Active drug to active metabolite (Procainamide - acetylation - N-acetylprocainamide)
- Inactive drug to active metabolite (Codeine - demethylation - morphine)
- Active drug to reactive metabolite (acetaminophen - reactive metabolite / liver toxicity)
What does absorption mean?
Anytime a drug has to pass a biological membrane
Which route of administration goes right into the systemic system?
Intravenously
Which route of administration avoids the need to cross a biological membrane in order to reach the CNS?
NONE
The six factors that determine movement of a drug across membranes?
- Characteristics of the membrane
- Mechanism of passage across membrane
- Dwell time of drug-membrane interface
- Physiochemical characteristics of the drug
- pH of the microenvironment
- Surface area of absorptive surface
Where does most drug absorption occur?
In the small intestine / microvilli and vili and its increased surface area (EVEN if it gets favored in the stomach)
What impact would a drug that speeds up stomach emptying have on the time to peak concentration for acetaminophen?
It will be higher because it will be absorbed more quickly
What is passive diffusion
Where drugs can passively diffuse through aqueous channels in the intercellular junctions or through lipid cell membranes
What is active diffusion
Where drugs can pass through but they need energy either through carriers or by membrane limited vesicles in or out of the cell
What is the driving force for movement of a drug across membranes via transcellular or paracellular diffusion?
Will always move with the concentration gradient (high to low)
What % of drugs use transcellular diffusion?
95%
Transceullar diffusion
passive diffusion across membrane is dependent on compound pKa and solution pH
How can you increase transcellular permeability?
- remove ionized groups
- increase lipophilicity
- reduce the size
paracellular diffusion
not a lot of drugs can do this, has to be super small to pass through, but toxins are being explored to be able to open these tight junctions to make bigger molecules fit.
The rate of diffusion is impacted by…….
diffusion coefficient, partition coefficient, membrane thickness, surface area of membrane
Saturation point
There is a fixed point where even if you add more drug it will not show more effect
Carrier mediated transport?
In contrast to simple diffusion, carrier mediated transport is both saturable and subject to competitive inhibition
As you increase the dose of riboflavin the amount decreases as the dose gets higher because it is totally saturable.
yup
What happens when you take food with medication?
The GI slows down causing the drug to be more actively absorbed.