basic concepts and processes Flashcards
1
Q
name some different functions cells carry out
A
- take in raw materials
- manufacture products required to maintain bodily functions
- deliver those manufactured products to the appropriate destination within the body
- differ from one tissue to another
- exchange materials with immediate environment
- obtain energy from nutrients
- reproduce
- communicate with one another via biologic chemicals
2
Q
True or False?
while all cells differ from one tissue to another, they share certain common characteristics
A
True
rationale: while all cells differ from one tissue to another, they share common characteristics, including the ability to exchange materials from their immediate environment, obtain energy and nutrients, synthesize complex molecules, reproduce, and communicate with one another via biologic channels
3
Q
drugs must interact with cell membrane to affect…
A
cellular function
4
Q
most drugs are given for ______ effect (most often occurs at a cellular level)
A
systemic
5
Q
what moves drug molecules through the body
A
transport pathways and mechanisms
6
Q
what are the three main pathways of drug movement across cell membranes?
A
- direct penetration of the membrane by lipid soluble drugs (most common)
- passage through protein channels
- carrier proteins
7
Q
describe direct penetration of the membrane by lipid soluble drugs
A
- lipid soluble drugs dissolve in the lipid layer of the cell membrane and diffuse into or out of the cell
- most systemic drugs are formulated to be lipid soluble
- most common pathway
8
Q
describe passage through protein channels
A
- gated channels regulate the movement of ions
- only a few drugs are able to use this pathway because most drug molecules are too large to pass through
9
Q
describe using carrier proteins as a pathway into the cell
A
- carrier proteins attach to the drug molecules and move them across cell membranes
- all carrier proteins are selective in the substances they transport; a drugs chemical structure determines which carrier will transport it
10
Q
describe pharmacodynamics
A
- effect the drug has on the body
- reactions between living systems and drug/drug actions on target cells and the resulting alterations in cellular biochemical reactions and functions
11
Q
what are the four ways drugs primarily work
A
- to replace or act as substitutes for missing chemicals
- to increase or stimulate certain cellular activities
- to depress or slow cellular activities
- to interfere with the functioning of foreign cells leading to cell death (chemotherapeutic drugs)
12
Q
describe the receptor theory of drug action
A
drugs exert their effects by chemically binding with receptor cells through…
- activation, inactivation, or alteration of intracellular enzymes
- changes in the permeability of cell membranes to one or more ions
- modification of the synthesis, release, or inactivation of neurohormones
13
Q
describe receptors
A
specialized protein structures that are found on cell membranes
14
Q
drugs designed to target specific types of receptors to initiate, limit, or prevent a ________
A
biologic response
15
Q
with receptors, response to a drug will depend on…
A
the affinity or attraction to a receptor and the concentration of the drug already at the receptor site
16
Q
describe agonist
A
drugs that produce or prolong activity
17
Q
describe antagonists
A
- drugs that block a response
- can be competitive for the receptor site
18
Q
relatively few drugs do not act on receptor sites. drugs in the following classes apply…
A
- antacids
- osmotic diuretics
- several anticancer drugs
- metal chelating agents
19
Q
describe nonspecific drug effect
A
- selective to certain receptors but those receptors may be in different organs or tissues (ex. cholinergic receptors)
- produce response wherever a particular type of receptor exists
20
Q
describe an example of nonspecific drug effect
A
- bethanechol
- cholinergic receptor sites in heart, blood vessels, stomach, bronchus, and eye
- response include decreased HR, decreased BP, increased gastric secretion, constricted bronchioles, and constricted pupils
21
Q
describe nonselective drug effect
A
not selective to just one type of receptor, it can act on different receptors throughout the body
22
Q
describe an example of nonselective drug effect
A
- epinephrine affects receptors Alpha 1, Beta 1, and Beta 2
- Alpha 1 receptors are found in blood vessels, causes an increase in BP
- Beta 1 receptors are found in the heart, causes and increase in HR
- Beta 2 receptors are found in the bronchus, causes relaxed bronchioles
23
Q
describe pharmacokinetics
A
drug movement through the body to reach sites of action, metabolism and excretion
24
Q
what are some specific processes of pharmacokinetics
A
absorption, distribution, metabolism (biotransformation), and excretion
25
describe **absorption**
- process that occurs from the time a drug enters the body to the time it enters the blood stream to be circulated to tissues
- process: active and passive transport
26
describe active transport
- molecule move across a membrane from an area of low concentration to an area of high concentration
- takes energy
27
describe passive transport
- movement across a membrane from area of high concentration to an area of low concentration
- no need for energy
28
**absorption**
onset of drug action is determined by…
the rate and extent of drug absorption
29
what factors affect rate and extent of drug absorption
- dosage, form, route of administration
- administration site blood flow, GI function (gastric pH)
- the presence of food or other drugs
30
absorption of enteral medication includes…
meds given by mouth or any GI tubes
31
absorption of enteral medications can be altered by…
- GI motility
- presence of food in stomach
- pH of stomach
- amount of bowel surface area
- can be influence by pain, stress that could divert blood flow from GI/stomach
32
which is faster?
enteral or parenteral absorption?
parenteral
33
describe absorption of parenteral (outside of GI tract) drugs
includes routes such as IV, IM, and Sub Q
34
how can absorptions of parenteral drugs be altered
- altered blood flow to area (think about temp and vascular issues)
- altered by tissue type (fat or muscle) (this is important with Sub Q or IM med injection)
- muscle tissue has more blood vessels, so absorption is faster
- Sub Q tissue (fatty) has less blood vessels so absorption is slower
- IV administration is not affected by absorption “rules” since the drug is immediately administered into the bloodstream/circulation
35
rank the ways of absorption from fastest to slowest
1. IV
2. IM
3. Sub Q
4. enteral
36
describe distribution
- the transportation of drug molecules within the body
- drugs are carried by blood and tissues fluids to action sites/metabolism sites/excretion sites
- depends on adequacy of blood circulation
37
distribution process can be affected by
- protein binding
- when drug is bound to protein it is inactive, unbound drug is free, active drug
- only unbound drug to able to move through capillaries
38
describe protein binding
- drugs attach to protein molecules and travel to site of action (mostly bind to albumin)
- allows for part of the drug to be stored as needed and can be distributed over time
39
describe why medications with low or loose protein binding capacity are going to have less duration of action
because they will be released faster in the bloodstream, there will not be a lot of binding to keep the drug around in the system
40
describe how protein bound drugs are dosed to keep the body at normal levels
when bloodstream level of the drug goes down because the active (unbound) drug is excreted, the inactive (bound) drug is then released from the protein (albumin) and the drug stays in the blood
41
why could a patient with hypoalbuminemia experience toxicity from excessive free drug in the body
little to no albumin for drug to bind to, it is important they are monitored for the excessive free drug
42
where else can drugs be stored in the body (other than the bloodstream)
- muscle, fat, and other tissues. drug is release as plasma drug levels go down in the blood
- drugs that are stored extensively in other tissues have a long duration of action
43
describe the blood-brain barrier
- the blood-brain barrier is composed of capillaries with tight bonds in the CNS
- these capillaries limits the passage of most ions and large molecular weight compounds (including some drugs) from the blood to the brain
- to pass the blood-brain barrier, medications must be highly lipid soluble
44
describe some considerations to take with drug distribution during pregnancy and lactation
- most drugs cross the placenta and may affect the fetus
- many drugs enter breast milk and may affect nursing infant
45
describe how drugs lipid solubility affects distribution
- drugs can be lipophilic or lipophobic
- fat is required in the diet for strong cell membranes
- only drugs that are lipid soluble or have transport mechanisms can cross the blood brain barrier and reach therapeutic concentrations in brain tissue
46
describe how drugs ionization affects distribution
ionized drugs (positively charged) are not as well absorbed as nonionized drugs
47
how does perfusion of reactive tissue affect distribution
status of the vascular system is highly important to distribution
48
describe metabolism (AKA biotransformation)
- the method by which drugs are inactivated or biotransformed by the body
- can be:
- changes into new, less active chemicals to be excreted
- from active in inactive metabolites then excreted
- "prodrugs" initially inactive/become active when metabolized
-
49
metabolism occurs primarily in which organ?
liver
50
drug metabolizing enzymes are located within which organs
- kidneys
- liver
- RBCs, plasma
- lungs
- gastrointestinal mucosa
- diseases of these organs can affect the impact of the drug
51
what is the most important site of drug metabolism and what enzyme metabolizes the drugs
liver, cytochrome P-450 (CYP)
52
describe the first pass effect
- phenomenon of drug metabolism whereby the concentration of the drug, specifically when administered orally, is greatly reduced before it reaches the systemic circulation
- fraction of the drug is lost through absorption
- med goes through liver and part of the drug is lost
53
describe enzyme induction
- with _chronic administration_ of a drug, the liver produces more enzymes to metabolize the drug
- this accelerates drug metabolism because larger amounts of enzymes allows larger amounts of the drug to be metabolized within a given period
- dose of drug must be increased
54
describe enzyme inhibition
- concurrent administration of two drugs that require the same enzyme for breakdown
- there is a decrease in metabolism because the enzyme has to do double the work and there is competition for the use of the enzyme
- it is important to look for symptoms of the drugs because there may be increased levels of the drugs in the bloodstream. in this case, smaller doses may be needed to avoid adverse effects and toxicity
55
describe excretion
- elimination of a medication from the body
- requires adequate function of organs of excretion
56
name the organs/methods of excretion
- kidneys
- skin
- saliva
- lungs
- bile
- feces
57
what is the most important organ of excretion
kidneys
58
what do the lungs excrete from the body
volatile gases such as anesthesia
59
what labs are used to determine adequate kidney function and what are the normal adult values?
- Glomerular Filtration Rate (GFR) \>60
- BUN 10-20mg/dl
- creatinine 0.7-1.4
60
what factors affect excretion
- glomerular filtration rate (GFR)
- urine acidity
61
describe urine acidity
- determines the ionization state
- normal pH is 4.5-8
- can affect reabsorption and excretion on weak acids and decrease absorption of weak bases
62
**True or False?**
absorption is the transport of drug molecules within the body
**False**
**Rationale:** Distribution is the transport of drug molecules within the body. Absorption is the process that occurs from the time a drug enters the body to the time it enters the bloodstream to be circulated
63
what clinical factors influence drug therapy
- age and weight
- present health disorders
- other disease entities
- client drug compliance
64
what administration variable influence drug therapy
- drug form
- route of drug administration
- multiple drug therapy
- drug interactions
65
what pharmacokinetics variables influence drug therapy
- absorption
- distribution
- metabolism
- excretion
66
what pharmacodynamics variables influence drug therapy
- onset, peak, and duration
- therapeutic range
- side effects and adverse reactions
67
describe onset
time it takes to produce a response
68
describe peak
time to reach highest effective concentration
69
describe trough
lowest level of concentration reached before next scheduled dose
70
describe duration
length of time that the concentration is great enough to produce a response
71
describe plateau
maintained level of concentration with repeated fixed doses
72
name and describe some different patient related variables
- **pharmacogenomics -** study of genetic variations in drug responses; individual variations in drug response are often attributed to genetic heritage, which produces different drug reactions; pharmacogenomic influences on drug response alters pharmalogic effects
- **genetics -** genetic polymorphism (genetic variations may influence any of the chemical processes by which drugs are metabolized)
- **sex and ethnicity -** most drug information has been derived from clinical drug trials using Caucasian men
- **Preexisting conditions -** many can affect drug responses (examples include cardiac issues, diabetes, hypertension etc)
- **Psychological factors -** preconceived notion
**-tolerance -** same dose of drug no longer elicits the same response - need to increase dose
-**cross tolerance -** person is tolerant to a certain drug, causing them to develop a tolerance to a similar drug
73
describe serum drug level
-a laboratory measurement of the amount of a drug in the blood at a particular time
74
what does serum drug level represent?
- dosage, absorption
- bioavailability, half-life
- rates of metabolism and excretion
75
describe half-life
the time it takes for the amount of drug in the body to decrease to one half (50%) of the peak level it has previously achieved
76
what does half life determine?
Half life determines appropriate timing and dosing
77
what factors affect half life?
- absorption rate
- distribution
- speed of biotransformation
- rate of excretion
78
describe therapeutic index (TI)
the margin between effectiveness and toxicity of a medication
79
describe a narrow TI medication and give an example
- very dangerous r/t the margin of the level of acceptable blood levels is very narrow
- ex. Digoxin (cardiac glycoside): + inotropic medication that improves heart muscle contractility in heart failure pts
- patients taking digoxin must have their serum blood levels drawn to be sure they are within the acceptable level (not subtherapeutic/therapeutic/not toxic TI+0.5-2ng/ml)
80
describe the **minimum effective concentration (MEC)**
- must be present for the drug response to be produced, although there may be numerous drug molecules in the body, drug action stops when levels fall below MEC
- largely determined by the drug dose and how well it is absorbed into the bloodstream
81
describe **loading dose**
- larger than normal volume of drug given initially to obtain a more rapid therapeutic blood level of that drug to produce a response
- ex. digoxin
82
describe **toxic concentration**
- excessive level of medication in the bloodstream
- caused by a single large dose, repeated small doses, or slow metabolism of medication
83
describe dosage as a drug related variable
- dosage refers to the frequency, size, and number of doses
- it is a major determinant of drugs actions and responses, both therapeutic and adverse
84
describe route of administration as a drug related variable
affect drug actions and patient responses largely by influencing absorption and distribution
85
describe drug-diet interactions
- a few drugs are used therapeutically to decrease food absorption in the intestinal tract
- however, most drug-diet interactions are undesirable because food often slows absorption of oral drugs by slowing gastric emptying times and altering GI secretions and motility
- in addition, some food contains certain substance that react with certain drugs (ex. coumadin and vitamin K)
86
describe drug-drug interactions
- the action of a drug may be increased or decreased by its interaction with another drug in the body
- the basic cause of many drug-drug interactions is altered drug metabolism
87
name some drug interactions that can increase therapeutic or adverse effects
- additive effects
- synergism
- interference
- displacement
88
name some drug interactions which drug effects may be decreased
- antidote medication
- decreased intestinal absorption of drugs
- increased metabolism rate of drugs
89
describe **additive effects**
occurs when two drugs with similar pharmacologic actions are taken, increases effects
90
describe **synergism**
occurs when two drugs with different sites o mechanisms of action produce larger effects when taken together
91
describe **interference**
two drugs are given together and one drug affects the metabolism of the other, may result in intensified effects of the second drug
92
describe **displacement**
occurs when a drug with a strong attraction to protein-binding sites may displace a less tightly bound drug
93
describe **antidote medication**
given to antagonize the toxic effects of another drug (ex. narcan)
94
describe **decreased intestinal absorption of drugs**
occurs when drugs combine to produce nonabsorbable drugs, or when preexisting intestinal condition is present
95
describe **increased metabolism rate of drugs**
activation of drug metabolizing enzymes decreases the drugs effects
96
describe adverse effects
- any undesired responses to medication administration
- all drugs can produce adverse effects
- can occur with usual therapeutic dosing
- more likely to occur or be more severe with high dosing
- especially likely to occur with specific drugs and in older adults who take multiple drugs
97
same some common or serious adverse drug effects
- CNS effects
- GI effects
- hematologic effects
- nephrotoxicity
- hypersensitivity
- serum glucose levels
- drug fever
- idiosyncrasy
- drug dependence
- carcinogenicity
- teratogenicity
98
describe **CNS adverse drug effects**
- *CNS stimulation* may result in agitation, confusion, disorientation, hallucinations, psychosis, or seizures
- *CNS depression* may result in impaired level of consciousness, sedation, coma, impaired respiration and circulation
99
describe **gastrointestinal adverse effects**
- commonly occur
- include nausea, vomiting, constipation, diarrhea
- more serious effects include bleeding and ulceration (most often occur with NSAIDS) and severe diarrhea/colitis (most often with antibiotics)
100
describe **hematologic adverse effects**
- relatively common and potentially life threatening
- includes excessive bleeding, clot formation, bone marrow depression, and anemias
- often associated with anticoagulants and thrombolytics
101
describe **nephrotoxicity**
- nephritis, renal insufficiency or failure
- occurs with antimicrobial agents, NSAIDS, and others
- potentially serious because it may interfere with drug excretion, thereby causing drug accumulation and increased adverse effects
102
describe **hypersensitivity**
- may occur with almost any drug in susceptible patients
- largely unpredictable and unrelated to dose
- produce reactions ranging from mild akin rashes to anaphylactic shock
103
describe **serum glucose levels** as related to adverse drug effects
- certain meds increase blood sugar levels (reg= 70-110)
- not good for diabetics (must really watch blood glucose levels)
- common meds that cause increased blood sugar are steroids
104
describe **drug fever**
- most common mechanism for causing drug fever is allergic reaction
- other mechanisms include damaging body tissues, interfering with dissipation of body heat, or acting on the temperature regulating center in the brain
105
describe **idiosyncrasy**
- refers to an unexpected or unexplainable reaction to a drug
- usually attributed to genetic characteristics
106
describe **drug dependence** as an adverse effect
- may be physiologic or psychological
- physiologic dependence produces unpleasant physical symptoms when dose is reduced or drug is withdrawn
- psychological dependence leads to excessive preoccupation with drugs and drug seeking behavior
107
describe **carcinogenicity** as an adverse effect
ability of a substance to cause cancer
108
describe **teratogenicity**
- ability of a substance to cause abnormal fetal development when taken by pregnant women
- pregnancy category X
109
describe **black box warning**
indicates that a med may cause serious life threatening effects and FDA requires there is a black box warning on medication making sure everyone is aware of the high alert
110
describe drug overdose
- can be intentional or accidental
- results from excessive amounts of medication
- common problem in both adult and pediatric populations
- may result from single large dose or prolonged ingestion of smaller doses
- may involve alcohol, prescription, OTC or illicit drugs
- can be a medical emergency, regardless of location
111
what are the main goals of treatment with drug overdose
- starting treatment soon after ingestion
- supporting and stabilizing vital function
- preventing further damage by reducing absorption, increasing elimination, and administering antidotes whenever possible
