pharmacology Flashcards
What is pharmacodynamics?
the study of what the drug does in the body, including mechanism by which a drug exerts its effect on the body
- includes distribution and metabolism
What is a drugs mechanism of action?
how the drug produces its effects, not the site of action
- sequential steps following drug binding to receptor
- followed by signal transduction steps
what is a drugs site of action
location in the body where the drug exerts its therapeutic effect
what is the most common way to classify drugs
According to their mechanism of action
What role do receptors play int he drug therapeutic decision making
- primary determinate in does size and effect
- selectivity of drug actions
- mediate action of agonist and antagonist
What is the difference between an agonist and antagonist drug
- agonist bind to a receptor and mimic the effect of the endogenous signaling compound
- antagonist bind to the receptor and block the actions of the endogenous signaling compound
what is drug potency
measure of the strength, or concentration, of a drug required to produce a specific effect
- the greater the potency the less the drug is needed and the lower the change of an ADR
what is a drug’s maximum efficacy
the extent or degree of an effect that can be achieved
what is ceiling effect
increasing dose no longer produces a response
What is drug efficacy
The ability of a drug to accomplish the desired outcome
What is the difference between a graded dose response curve and a quantal dose response curve
- Graded - depiction of observed effects of a drug as a function of its dose in individuals, single test subjects or homogenous populations. The dose is slowing increased and the response is observed
- Quantal - a predetermined drug effect is set (median effective ED50 or median toxic TD50) and a population is provided with increasing doses. Each person is classified in has or does not have the predetermined effect.
What is the purpose of dose response curves
they are used to study the effects of a drug in order determine to proper therapeutic dosing
What is the therapeutic index of a drug
- a quantal dose response variable
- ratio of individuals achieving median effect dose (ED50) producing the desired response to individuals achieving the median toxic dose (TD50) producing the negative drug effect
- greater the ratio the safer the drug
what are the different pathways of drug adverse reactions (3)
- mechanism based - extension of the drugs principal pharmacological actions
- off target - consequences of the drugs molecules not drug actions - hepatoxicity of acetaminophen is an example
- idiosyncratic - interaction of the drug with unique HOST factors and do not occur in the population at large
What drug characteristics will predict its ability to move in the body
Molecular…
- size
- shape
- ionization
- lipid solubility
- ability to bind to serum and tissue protein
What are the primary barriers to drug movement in the body
Membranes (capillary, GI, blood-brain, cellular)
What variables predicts a drugs ability to passively diffuse across a membrane
- diffuse along concentration gradients
- solubility in the lipid bilayer or permeability coefficient
- membrane surface area
What is permeability coefficient
how well a drug travels through the lipid bilayer
- dependent on participation coefficient (degree of innate lipid solubility) and degree of ionization (greater the ionization the more effect it takes to get through the membrane)
What is the Flick low of diffusion
formula for describing passive diffusion across a plasma membrane
- difference in concentration between outside and inside
- surface area exposed to the drug
- permeability coefficient
- distance across membrane
What are the key factors impacting a drug’s ionization
- the pH of the body fluids which the drug is dissolved
2. ionization constant of the drug itself
how does the pH of the body fluid in which the drug is absorbed impact drug movement across membranes
- acidic drugs are non-ionized by acidic fluid thereby increasing their absorption rate (stomach acid makes them easier to absorb)
- basic drugs are non-iononzid by basic fluid such as the upper GI tract
- the drug will also tend to accumulate in areas where their ionization increased due to the decreased ability to cross the membrane
what is bioavailability
fraction of unchanged drug reaching the systemic circulation following administration by any route
what is first pass effect
a phenomenon of drug metabolism whereby the concentration of a drug is greatly reduced before it reaches the systemic circulation (metabolized or filtered out by liver)
what is the difference between enteral and parenteral administration of a drug
enteral - oral, sublingual or rectal
parenteral - inhalation, IV, SQ, IV, TD, topical
