Module 1 Flashcards
Define drug
Any chemical that can affect living processes
What’s another name for therapeutics?
Pharmacotherapeutics
Define therapeutics/pharmacotherapeutics
The use of a drug to diagnose, prevent, or treat disease, or to prevent pregnancy
What are the 3 most important properties of an ideal drug?
Effectiveness
Safety
Selectivity
What is the most important property a drug can have?
Effectiveness
What does safety of a drug mean?
A drug cannot produce harmful effects
What is selectivity of a drug?
The drug elicits only the response for which it is given
What are some examples of adverse effects of drugs?
- Anticancer drugs can increase risk for infection
- Opioid analgesics at high doses can cause respiratory depression
- Aspirin etc. can cause gastric ulceration, perforation, and bleeding when taken for prolonged periods of time
What are the additional properties of an ideal drug?
Reversible action
Predictability
Ease of administration
Freedom from drug interactions
Low cost
Chemical stability
Simple generic name
What is an example of a reversible agent?
Narcan (needed for when someone overdoses on opioids)
What is the therapeutic objective of drug therapy?
To provide maximum benefit with minimum harm
What are the factors that determine the intensity of drug responses?
Administration
Pharmacokinetics
Pharmacodynamics
Sources of individual variation
What is the intensity of a drug response determined by?
The concentration of a drug at its sites of action
What primarily determines the concentration of a drug at its sites of action?
The administered dose
What are some factors that could affect administration of a drug?
Medication errors
Patient adherence
What do pharmacokinetic processes determine?
How much of an administered dose gets to its sites of action
What are the 4 major pharmacokinetic processes?
Drug Absorption
Drug Distribution
Drug Metabolism
Drug Excretion
What do pharmacodynamic processes determine?
Once a drug has reached its sites of action, these processes determine the nature and intensity of the response (the impact of drugs on the body)
Which determines the rout the medication should be given in
What factors affect pharmacodynamics?
Drug-receptor interaction
Patient’s functional state
Placebo effects
What does sources of individual variation mean?
Characteristics unique to each patient which can influence pharmacokinetic and pharmacodynamic processes, and by doing so, can help determine a patient’s response to a drug
Which categories are sources of individual variation?
Physiologic variables
Pathologic variables
Genetic variables
Drug interactions
With administration of a drug, what are important determinants of drug responses?
Dosage size
Route
Timing
Medication errors
Patient adherence
Define pharmacokinetics
Determining how much of the administered dose gets to its sites of action
(Impact of the body on drugs)
Define pharmacodynamics
The impact of drugs on the body
What does drug-receptor interaction mean?
Binding of the drug to its receptor
What does a patient’s functional state have to do with pharmacodynamics?
Influences pharmacodynamic processes
What do placebo effects do?
Help determine the responses a drug elicits
Examples of physiologic variables
Age
Gender
Weight
Examples of pathologic variables
Diminished functions of the kidney and/or liver
Which process can genetic variables affect when drugs are administered?
Can alter the metabolism of drugs and predispose the patient to unique interactions
What are the 5 drug rights?
Right patient
Right drug
Right dose
Right route
Right time
What are the other important drug rights?
Right assessment
Right documentation
Right evaluation
Right of patient education
Right of patient to refuse care
What does it mean for nurses to have other nursing responsibilities regarding drugs?
Nurses must be involved with participating in promoting beneficial effects to minimize harm to patients.
Responsibilities regarding drugs the nurse must be involved with:
What drugs are appropriate?
What drugs are contraindicated?
What are possible interactions?
The role of an advocate
Last line of defense for the patient
What is an example of how a nurse is involved with applying pharmacology for patient care?
Determining if a medication is working by taking pt’s BP before administering the BP med and then rechecking it later to make sure BP is lower
What is an example of a nurse being involved with applying pharmacology for patient education?
“This medication is called ________. It’s for your BP”
What are the 8 aspects of drug therapy that applies pharmacology in patient care?
- Preadministration assessment
- Dosage and administration
- Evaluating therapeutic effects
- Minimize adverse effects
- Minimize adverse interactions
- Make prn decisions
- Manage toxicity
How would a nurse perform a preadministration assessment?
Collect baseline data
Identify high-risk patients (drug allergies, age groups, lab results, etc.)
How would a nurse focus on dosage and administration when applying pharmacology in patient care?
What is the route?
Drugs can have different uses
Read the order
Verify the patient
Dosage calculations?
Be sure you know what the drug is
How would a nurse evaluate and promote therapeutic effects of a drug?
Must know the rationale for treatment and the nature and time course of the intended response
(Cannot effectively evaluate a drug with multiple applications if the intended use is not known)
How can a nurse minimize the adverse effects of a drug?
** Always know:
The major adverse effects of the drug
Early signs that an adverse reaction is developing
The times when these reactions are likely to occur
Interventions that can minimize discomfort
Take a thorough drug history
Avoid over the counter drugs that can interact
Monitor for adverse interactions that are known to occur
What does PRN stand for?
Pro re nata
What does PRN mean for a nurse?
“As needed”
The nurse has the discretion regarding how much drug to give and when to give it
What are two important things a nurse must take into consideration when giving a prn medication?
Know the reason for the drug’s use
Be able to assess the patient’s medication needs
How can a nurse manage toxicity?
Early identification makes early intervention possible
Know the early signs of toxicity
Know the procedure for toxicity management
*What should a nurse educate a patient on about their medication?
- Drug name and category
- Dosage size, dosing schedule
- Route and technique of administration
- Expected therapeutic response
- Nondrug measures to enhance therapeutic responses
- Duration of treatment
- Drug storage
- Symptoms of major adverse effects and how to minimize
- Major adverse drug-drug and drug-food interactions
- Whom to contact in the event of therapeutic failure, severe adverse reactions, or severe adverse interactions
What are things to keep in mind to best provide patient education?
How to take the drug
Explain in words they can understand
Specifics about the drug
Food interactions
Write things down
What are the steps of the nursing process?
Assessment
Analysis
Planning
Implementation (intervention)
Evaluation
How does assessment apply in drug therapy?
Preadministration assessment
Data collection
How does analysis apply during drug therapy?
Nursing diagnosis
Is the drug appropriate?
How does planning apply to drug therapy?
Identifying specific interventions
Patient education
How does implementation apply to drug therapy?
Drug administration
Therapeutic effect
Adverse reactions
Patient education
How does evaluation apply to drug therapy?
Therapeutic responses
Interactions?
Is the patient satisfied with the treatment?
What is the nursing process format to summarize nursing implications with drug therapy?
1- Preadministration assessment
2- Diagnosis and planning, which includes what the drug is for
3- Implementation: administration
4- Implementation: measures to enhance therapeutic effects
5- Ongoing evaluation and interventions
Patient education
What did the Federal Pure Food and Drug Act mean?
Drugs needed to have labels on them
What did the Food, Drug, and Cosmetic Act say?
That drugs needed to have their ingredients disclosed on them
What did the Harris-Kefauver Amendments say?
Drugs must be known to be effective before giving them (need proof of effectiveness)
What did the controlled substances act say?
Created categories for drugs (Schedule 1-5)
What did the permission for accelerated drug approval say?
Created a sped up process to get meds out faster in times of need (like the AIDS crisis)
What are randomized controlled trials (RCTs)?
The most reliable way to objectively assess drug therapies. Minimize the influence of personal bias on the results
The three distinguishing features of randomized controlled trials:
Use of controls
Randomization
Blinding
What is preclinical testing?
Required before a new drug may be tested on humans
Performed on animals
May take 1-5 years
What properties are drugs evaluated for during preclinical testing?
Toxicities
Pharmacokinetic properties
Potentially useful biologic effects
How many phases in clinical testing?
4
How long does clinical testing take?
2 to 10 years
What occurs during phase 1 of clinical testing?
Conducted in healthy volunteers
What are the 3 goals of phase 1 of clinical testing?
Evaluate drug metabolism
Pharmacokinetics
Biologic effects
What occurs during phases 2 and 3 of clinical testing?
Drugs are tested in patients
Drug manufacturer applies to the FDA for conditional approval at the end of phase 3
What occurs during phase 4 clinical testing?
Postmarketing surveillance
New drug is released for general use and observed
What are some limitations of the clinical testing procedure?
Limited information about the majority of people (women and children)
Failure to detect all adverse effects
What guideline should clinicians regarding the discretion of new drugs?
- Be neither the first to adopt the new nor the last to abandon the old
- Balance potential benefits against inherent risks
- New drugs generally present greater risks than old ones
What are the 3 types of drug names?
Chemical name
Generic name (or nonproprietary)
Trade name (or proprietary)
What is the problem with generic names?
More complicated than trade names
What are problems with trade names?
Single drug can have multiple trade names
U.S. drugs and drugs outside the U.S. may have different active ingredients
How many OTC drugs account for doses administered?
60%
How many more illnesses are treated by OTC vs. visiting a physician?
4 times more
Sources of drug information
Clinicians and pharmacists
Poison control centers
Pharmaceutical sales representatives
Sources for Published drug information
Newsletters
Reference books
The internet
Physicians’ desk reference online
Define pharmacokinetics*
*The study of drug movement throughout the body
Also includes *drug metabolism and *drug excretion
How does pharmacokinetics apply in therapeutics?
Through the passage of drugs across membranes
What are the three ways to cross a cell membrane?
Pass through channels or pores
Pass with the help of transport systems
Direct penetration of the membrane
What are the four basic pharmacokinetic processes?
Absorption
Distribution
Metabolism
Excretion
What occurs when we apply the knowledge of pharmacokinetics to drug therapy?
We can help maximize beneficial effects and minimize harm
What is P-glycoprotein?
A transmembrane protein that transport a wide variety or drugs OUT of cells
Role of the liver involving drugs
Transports drugs into the bile for elimination
Role of the kidneys involving drugs
Pumps drugs into the urine for excretion
Role of the placenta involving drugs
Transports drugs back into the maternal blood
Role of the brain involving drugs
Pumps drugs into the blood to limit drugs’ access to the brain
Which way do most drugs across membranes and why?
Penetrate membranes directly
- Because most drugs are too large to pass through channels or pores
- Most drugs also lack transport systems to help them cross all of the membranes that separate them from their sites of action, metabolism, and excretion
Explain how “like dissolves like” relates to drugs penetrating cell membranes
Cell membranes are composed primarily of lipids; therefore, to directly penetrate membranes, a drug must be lipid soluble (lipophilic)
What are quaternary ammonium compounds?
Molecules that contain at least one atom of nitrogen and carry a positive charge at all times
Because of positive charge, these compounds are unable to cross most membranes
Proton donor
Acid
Proton acceptor
Base
Tends to ionize in basic (alkaline) media
Acid
Tends to ionize in acidic media
Base
What is ionization?
The process of the acid giving up a proton or the base accepting a proton, which converts the acid or base into a charge particle - an ion
What is ion trapping (pH partitioning)?
Where there is a pH gradient between two sides of a membrane,
- acidic drugs accumulate on the alkaline side
- basic drugs accumulate on the acidic side
Define *absorption
*Movement of a drug from its side of administration into the blood
What determines how soon the effects of a drug will begin?
The rate of absorption
What determines how intense the effects of a drug will be?
The amount of absorption
How can the rate of dissolution allow drugs to be absorbed faster?
Drug formulations with faster dissolution absorb faster
How can surface area increase the rate of drug absorption?
Larger surface area (ex: small intestine)
How does blood flow affect the rate of drug absorption?
Areas with more blood flow allow for faster absorption
How does lipid solubility affect drug absorption?
Highly lipid-soluble drugs can cross membranes that separate them from the blood much faster
How does pH partitioning affect drug absorption?
Drugs that have a tendency to be ionized in plasma are pulled from administration site faster and absorb faster
What barriers to absorption are there for intravenous medication?
None because absorption is bypassed (the IV puts the drug directly into the blood)
Absorption pattern of intravenous medication
Instantaneous and complete (b/c drug enters the blood directly)
Barriers to absorption of medication given an intramuscular route
Only barrier is the capillary wall, which is easy to pass through
Absorption pattern of drugs administered intramuscularly
1 - drugs with high water solubility absorb faster
2- if the injection site has high blood flow, the drug will absorb faster
Barriers to absorption of drugs administered subcutaneously
Only capillary wall, which is easy, so no significant barriers to absorption
Barriers to absorption for drugs administered orally
1 - epithelial cells that line GI tract (most major barrier)
2 - Capillary wall
What is the absorption pattern of oral medications influenced by?
Solubility and stability of drug
Gastric and intestinal pH
Gastric emptying time
Food in the gut
Coadministration of other drugs
Special coatings of the drug preparation
Movement of oral drugs after absorption
Must go to liver first
Then superior vena cava
Then eventually into general circulation
What protein may reduce intestinal absorption of some drugs and why?
P-glycoprotein
Because it pumps certain drugs out of epithelial cells and back into the intestinal lumen
Why are some drugs enteric-coated?
To protect the med from stomach acid so it doesn’t get broken down in the stomach and irritate the stomach lining
Define *distribution
Movement of drugs throughout the body
Which three factors determine drug distribution
Blood flow to tissues
Exiting the vascular system
Entering cells
Where do drugs leave the vascular system?
Capillary beds
How are drugs carried to tissues and organs of the body?
By the blood
What determines the rate of delivery of a drug
Blood flow
Which two pathologic conditions affect drug therapy?
Abscesses and tumors
Why is drug therapy not as effective for abscesses?
Abscesses are pus-filled pockets and do not have internal blood vessels
Must be drained first
Why is drug therapy not as effective for solid tumors?
Solid tumors have a limited blood supply at the core of them
How do drugs exit the vascular system?
Between the capillary cells of capillary beds rather than through them
What is the blood-brain barrier?
Tight junctions between the cells that comprise the walls of most capillaries in the central nervous system
How can drugs pass through the blood-brain barrier?
Drugs must be able to pass through the cells of the capillary wall because of the tight junctions between the cells
Which types of drugs are able to cross the blood-brain barrier?
Drugs that are lipid soluble
Or that have a transport system
Risks with drug transfer to the placenta:
Birth defects: mental retardation, gross malformations, low birth weight
Mother’s use of habitual opioids: birth of drug-dependent baby
What is protein binding?
Reversible bonds that drugs can form with various proteins
Most abundant and important protein
Plasma albumin
What does plasma albumin affect?
Drug distribution
How does plasma albumin affect drug distribution?
Is a large molecule that always remains in the blood stream
Drugs bind to it and it will float through the vascular system and distribute it
Why do drugs enter cells?
Some must enter to reach site of action
Most must enter to undergo metabolism and excretion
How do drugs act on cells without crossing the cell membrane?
Bind with receptors on the external surface of the cell membrane to produce their effects
Another name for drug metabolism
Biotransformation
Define biotransformation
Enzymatic alteration of drug structure
Where does drug metabolism most often take place?*
In the liver*
Most drug metabolism that takes place in the liver is performed by?
The hepatic drug-metabolizing enzyme system
AKA the P450 system*
What is the P450 system?
A network of 12 different enzymes that help with metabolizing, where most drug metabolism that takes place in the liver is performed
Six possible consequences of drug metabolism:
Accelerated renal drug excretion
Drug inactivation
Increased therapeutic action
Activation of prodrugs
Increased toxicity
Decreased toxicity
What is enterohepatic recirculation?
A repeating cycle in which a drug is transported:
From the liver into the duodenum (via the bile duct)
Back to the liver via the portal blood
Which drugs are enterohepatic recirculation limited to?
Drugs that have undergone glucuronidation
How does age affect drug metabolism?
In infants, drug metabolism is limited because the liver is not fully developed
Decreased metabolism in older adults
What is induction of drug-metabolizing enzymes?
When inducers (drugs that act on the liver to increase rates of drug metabolism) stimulate enzyme synthesis
How does induction of drug-metabolizing enzymes affect drug metabolism?
Can cause the drug to increase the rate of its own metabolism causing the need for the dose to be increased to maintain therapeutic effects
What is first-pass effect?
When the liver metabolizes an oral drug so quickly that it is inactivated on its first pass through the liver
How does nutritional status affect drug metabolism?
In a malnourished patients, drug metabolism may be compromised
How does competition among drugs affect drug metabolism?
When two drugs are metabolized by the same metabolic pathway, they may compete with each other
Rate of metabolism may be decreased and if depressed enough, a drug can accumulate to high levels
Define excretion
The removal of drugs from the body
What forms can drugs and their metabolites exit the body through?
Urine
Sweat
Saliva
Breast milk
Expired air
What are the steps in renal drug excretion?
Glomerular filtration
Passive tubular reabsorption
Active tubular secretion
Factors that modify renal drug excretion:
PH-dependent ionization
Competition for active tubular transport
Age
Most important organ for drug excretion
Kidney
What happens regarding drugs if both kidneys fail?
Duration and intensity of drug responses increase
What is the clinical significance of plasma drug levels?
Since we cannot measure a drug at its sites of action, we have to look at the amount of the drug present in plasma
What is the minimum effective concentration?
The plasma drug level below which therapeutic effects will occur
What is toxic concentration of plasma drug levels?
The plasma level at which toxic effects begin
What is therapeutic range of plasma drug levels?
There is enough drug present to produce therapeutic responses but not so much that toxicity results
What is the objective of drug dosing?
*to maintain plasma levels within the therapeutic range
Define half-life*
*the time required for the amount of drug in the body to decrease by 50%
What does half-life determine?
The dosing interval
How are plateau drug levels achieved?
Using repeated doses to build up drug levels until amount being excreted is equal to the dose amount
How long does it take to reach a plateau of a drug?
When a drug is administered repeatedly in the same dose, plateau will be reached in about 4 half-lives
Techniques for reducing fluctuations in drug levels:
- Continuous infusion
- Administer a depot preparation (administers drug slowly and steadily)
- Reduce size of each dose and dosing intervals
What is a loading dose?
Given to reach plateau more quickly for drugs that have longer half-lives
What is a maintenance dose?
After high drug levels have been established with a loading dose, plateau can be maintained by giving smaller doses
How long does it take for a drug to be eliminated after administration is discontinued?
Most of it will be eliminated over an interval equal to about 4 half-lives
