Lecture 7 Flashcards
Dose response curve depicts what?
The efficacy and potency of a drug
Depicts the drug dose vs. the magnitude of drug effect
Where is the maximal effect shown on a dose response curve?
The asymptote, this is where side effects may be increased but no additional therapeutic effect is increased.
What is affinity?
The ability of the drug to bind to a receptor
What is efficacy?
The relationship between receptor occupancy and the ability to initiate or alter a biological response.
What is potency?
The amount of drug required to produce and effect of given intensity.
What is ED50?
Median effective dose.
This is the dose at which 50% of people show a therapeutic effect.
What is TD50
Median toxic dose
This is the dose at which 50% of people show a toxic effect
Margin of safety
Also called the therapeutic window.
Ranges of doses between ED50 and serious effects of TD50
Describe Pharmacokinetics
Pharmacokinetics is the fate of a drug in the body (what the body does to the drug)
ADME
Describe pharmacodynamics
Pharmacodynamics is the biochemical and physiological effects of a drug on the body (what the drug does to the body)
What does ADME stand for?
Absorption, Distribution, Metabolism, and excretion
Absorption
The process of a substance entering the bloodstream
Distribution
The dispersion of substances throughout the fluids of the body
Metabolism
The breakdown of drug into metabolites
Excretion
The elimination of substances from the body.
What are some examples of pharmacodynamics
activity of a drug at intended target
the side effects
duration in the body
What factors can affect drug absorption?
chemical properties of the drug itself(i.e lipophilicity)
Drug formulation (extended release)
Presence of food, excess mucus or other drugs
What is first pass metabolism?
Orally administered drugs are often metabolized by the liver before reaching much of the circulatory system. This is first pass metabolism.
What is bioavailability?
Ratio of amount of drug entering systemic circulatory system to amount of drug ingested
What is the one-compatrment model? How is it different from the two or multicompartment model.
One compartment model is when a drug rapidly equilibrates with all body tissues. The two or multi compartment model differentially stays in specific tissues.
What can influence a drug to be either one-compartment of two- or multicompartment model?
The chemical properties of a drug
What is the BBB and how does it work?
The blood brain barrier.
The brain is protected from many drugs by tightened capillary walls.
What makes the tightened capillary walls of the BBB?
The endfeet of astrocytes which makes it much harder for many molecules to enter the brain.
What kind of drugs can pass easily through these barriers?
Lipid soluble drugs?
What binds drugs and can distribute them throughout the body?
Plasma proteins that are in the blood.
Will drugs that bind to a plasma membrane pass the BBB?
No, unless they detach from the plasma proteins. Thus drugs with high protein affinity may not be ideal for psychiatric disorders.
What is the most common plasma protein?
Albumin
What is T(1/2)
Elimination half life, the time it takes for the body to eliminate half of the peak blood levels.
What is steady state? And when does it usually occur?
Steady state refers to when the overall intake of a drug is in equilibrium with its clearance rate.
This usually occurs reached after 4-5 elimination half-lives.
What is CYP and what does it do?
Cytochrome p450s.
CYP is a liver enzyme that breaks down drugs.
What is UGT and what does it do?
UDP-glucuronyl transferases.
UGT is a liver enzyme that breaks down drugs.
What can create variability in rates of drug metabolism?
An example would be genetic variants of CYP and UGT
Metabolism often involves what?
Derivatization and conjugation
Are all drug metabolites inactive?
No, an example would be the metabolite norfluoxetine that is made from fluoxetine. Norfluoxetine is also an SSRI.
Name 5 modes of excretion
Urine, Feces, milk, sweat, expired air
