Lecture 3 - Drug Interactions and Drug Information Flashcards
What is the first step in providing quality drug information?
knowing the most appropriate resource for information
what is evidence based medicine
the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients
What are primary sources?
ORIGINAL CONTENT
often provide the most in-depth information about a topic. Allows readers to draw their own conclusions. Requires strong literature evaluation skills and a lot of time
what are some examples of primary sources (in a science context)
clinical research studies
scientific experiments
journal articles
what are secondary sources?
secondary sources synthesize findings FROM MULTIPLE PRIMARY RESOURCES
mainly are in the form of searchable databases that enable the retrieval of primary or tertiary resources
what are some examples of secondary resources
embase, Pubmed, meta analyses, systematic review articles
What are tertiary sources?
tertiary sources include information from BOTH PRIMARY AND SECONDARY sources.
They are typically condensed into a more digestible format
what are some examples of tertiary sources
textbooks
lexicomp, micromedex (compendia)
package inserts
websites (CDC, clinical trials.gov)
other online databases
Prescription medications are labeled with…
PI (Prescribing information)
or
USPI (United States Prescribing information)
What does the PI/USPI contain?
the FDA’s findings regarding the safety and efficacy of the prescription drug on humans under the label conditions of use
which should you look at 1st — primary, secondary, or tertiary sources
TERTIARY
Indexing or abstracting services are ____ sources
secondary
clinical studies are ___ sources
primary
textbooks, databases, and review articles are ___ sources
tertiary
Do clinical practice guidelines provide a “one size fits all” approach?
no
what are clinical practice guidelines and give an association who publishes them
clinical practice guidelines are statements that include recommendations intended to optimize patient care. These recommendations are formed by a systematic review of benefits and the assessment of the benefits and harms of alternative care options
ex: American Diabetes Association Standards of Care
Are internet searches allowed?
yes - internet searches can be useful in certain situations.
however, it’s important to evaluate the quality of all information provided
What internet websites are more likely to contain high quality information?
-educational institutions
-nonprofit medical organizations
-a division of the US gov
there is limited info on the internet — where should you reach out to to find the answer you’re looking for?
an expert in the field
what websites should we be recommending to consumers (patients)
health care organizations (mayo clinic, cleveland clinic)
disease or professsional societies (american diabetes association)
consumer-specific sections from tertiary resources (micromedex, lexicomp_
What is a drug interaction?
when 1 drug modifies the action of another drug in the body
when is there an increased incidence of interactions?
-in elderly patients
-in patients taking many medications
T/F —–
there are hundreds of interactions for drugs, but few are clinically significant enough to be contraindicated or require a change in dosage
true
what is pharmacokinetics?
pharmacokinetics refers to the effect the BODY HAS ON THE DRUG as it travels through ADME (absorption, distribution, metabolism, excretion)
pharmacokinetic interactions occur when…
one drug alters the ADME processes of another drug
absorption from the GI tract may be influenced by…
-agents that bind drugs
-agents that increase/decrease GI motility
-drugs that alter the p-glycoprotein and organic anion transports in the membran e
How can distribution of a drug be altered?
the distribution of a drug can be altered by other drugs that compete for binding sites on plasma proteins
Give an example of the distribution of a drug being altered
highly protein-bound drugs can be displaced from binding sites on albumin , leading to INCREASED DRUG CONCENTRATION IN THE BLOOF
Excretion of drugs by the kidney can be changed by…
drugs that reduce renal blood flow OR inhibit renal transport mechanisms
Give a specific example of excretion interactions
drugs that alter the pH of the urine can alter the ionization state of drugs that are weak acids or bases, leading to changes in renal tubular reaborption
most pharmacokinetic drug interactions occur during….
metabolism
what is metabolism?
the process of converting a drug into a form that can be excreted
in which 2 organs do enzyme-catalyzed metabolism reactions happen?
the liver and the intestines
the SUBSTRATE is…
the drug that is subject to the reaction
what is the name of the liver enzymes that metabolize most drugs?
cytochrome P450 isoenzymes
How many CYP enzymes are there?
how many of them metabolize most drugs?
50
5
which CYP metabolizes ~34% of all CYP 450 isoenzymes?
CYP 3A4
What do enzyme inducers do?
DECREASE THE CONCENTRATION OF SUBSTRATE DRUGS, which in turn, RAISES ENZYME ACTIVITY
if someone has a slow metabolism, will they have more or less drug in their body compared to the average person?
more drug in the body
if someone has a fast metabolism, will they have more or less drug in their body compared to the average person?
LESS drug in their body
what do enzyme inhibitors do
enzyme inhibitors INCREASE concentration of the substrate drugs which causes LESS functional enzymes and a DECREASE in the rate of drug metabolism
sometimes, inhibitors are used to….
PURPOSELY BLOCK DRUG METABOLISM
What is pharmacodynamics
the effect a drug has on some organism (the human body)
what are 3 pharmacodynamic interactions?
antagonism
additive effectives
synergism
potentiation
what is the pharmacodynamic interaction of antagonism?
interactions based on OPPOSING effects or actions
What is the pharmacodynamic interactions of additive effects
the algebraic summing of the effects of 2 drugs
(1+1 = 2)
What is the pharmacodynamic interaction of synergism?
when the result of an interaction is GREATER THAN THE SUM of the drugs used alone
(1+1=5)
what is the pharmacodynamic interaction of potentiation?
when one drug’s effect is increased by another agent that has no such effect
categorize the following pharmacodynamic interaction….
warfarin and aspirin causes an increased risk of bleeding
additive
categorize the following pharmacodynamic interaction….
Beta agonists (asthma) and beta blockers (cardiovascular) together cause potential for decreased efficacy of beta agonists
antagonism
categorize the following pharmacodynamic interaction….
sulfamethoxazole + trimethoprom when taken together, the effects of both antibiotics increase
synergism
categorize the following pharmacodynamic interaction…..
Amoxicillin works as an antibiotic; clavulanic acid helps overcome antibiotic resistance
potentiation
Besides drugs themselves, what else can result in drug interactions
herbal products/supplements/vitamins
alcohol and smoking can increase/decrease levels and effects of medications
