pharmodynamics Flashcards
What is the study of pharmodynamics ?
The study of the biochemical and physiologic effects of drugs and the molecular mechanisms by which those effects are produced
( What drugs to do the body and how they do it )
what is the dose response relationship ?
Relationship between the size of an administered dose and the intensity of the response produced
what does the dose response relationship determine ?
The minimum amount of drug to be used
The maximum response a drug can elicit
How much to increase the dosage to produce the desired increase in response
a dose response curve will show ?
the maximal efficacy and the relative potency
what is maximal efficacy ?
known as the largest effect a drug can produce ( height of curve)
what is relative potency?
The amount of drug that must be given in order to elicit a response Can be important if a lack of potency forces inconveniently large doses and implies nothing about the maximal efficacy
Drugs are?
Chemicals that produce effects by interacting with other chemicals
receptors are ?
Special chemicals in the body that most drugs interact with to produce effects
true or false, when a drug binds to a receptor, it is usually reversible
True
receptor activity is usually regulated by what ?
Endogenous compounds
what happens when a drug binds to a receptor ?
it will either mimic or block the action of endogenous regulatory molecule and either increase or decrease the physiological activity controlled by that receptor
receptors can be classifed as?
Normal points of control of physiological processes
under normal physiologic conditions, receptors function is regulated by ?
molecules that have been supplied by the body
drugs produce therapeutic effects by :
by helping the body use its preexisting capabilities
true or false, drugs can both block and mimic the bodies own regulatory molecules
True
what are the 4 primary receptor families ?
Cell membrane–embedded enzymes
Ligand-gated ion channels
G protein–coupled receptor systems
Transcription factors
True or false The more selective a drug is, the greater the side effects there will be
False, the more selective a drug is , FEWER the side effects there will be
receptors and drug selectivity rely on what kind of mechanism ?
A lock and Key mechanism ( does not however gurentee safety)
What is the simple occupancy theory ?
the intensity of response to a drug is proportional to the number of receptors occupied
maximal response is achieved with a drug when
When there is 100% receptor occupancy
What is affinity ?
means the strength of the attraction - a high affinity means they are very potent
what is intrinsic activity ?
ability for drug to activate receptor upon binding - higher intrinsic activity of a drug will mean there will be a more intense response seen in the maximal efficacy
what is an agonist ?
drug binds to receptor- there is a response
what is an antagonist ?
drug binds to receptor, there will be the blockage of a physiological response
what are non competitive antagonists ?
drug combines with multiple parts of the receptor and inactivates it
what are competitive agonists ?
what are partial agonists ?
drug binds to receptor, there is a diminished response
The number of receptors on the cell surface and the sensitivity to agonists can change in response to
continuous activation, down regulation, Desensitized or refractory
continuous inhibition of receptors will cause
hypersensitivty
what drug responses do not involve receptors ?
Simple physical or chemical interactions with other small molecules
name some kinds of drugs that dont use receptors
Antacids
Antiseptics
saline laxatives
chelating agents
what is the ED 50?
Measurement of interpatient variability , the dose produces an effect in 50 % of patients
what are some clinical implications of interpatient variability
The initial dose of a drug is necessarily an approximation
ED50 in a patient may need to be increased or decreased after the patient response is evaluated
what is the therapeutic index ?
ratio between LD50 which is the average lethal dose to 50% of animals tested with its ED50
The higher the therapeutic index means ?
The safer the drug
Age of a neonate ?
birth- 1 month
age of an infant ?
1-12 months
Age of a child
1- 12 years old
at what stage can a drug most easily pass through the placenta ?
during the last trimester ( blood flow to the fetus is the highest, increased surface area and increased amount of free drug circulating
drug induced development is at its greatest risk when ?
During the first trimester, due to the proliferation of cells and the fast development of organs
low serum creatinine is a indicator of?
poor kidney function
when there is a decline in renal functioning what happens ?
metabolism, declined cardiac output, delayed drug excretion, and possible drug accumulation because of this
why are hydrophiliic drugs a problem with older adults
they have less body water overall so the drug concentration could be higher for them
What are some characteristics of peds pts that will impact drug dosage?
skin is thinner and more permeable, stomach lacks acid to kill bacteria, lungs have weaker mucus barrier, liver and kidneys not fully developped, body temp not as well regulated ( more dehydration )
