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definition pharmacology
- science of drug effects
- deals with all drugs (legal and illegal)
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chemical name of a drug
- rarely used in nursing practice
- exact description of the drugs chemical composition and molecular structure
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definition drug
- chemical that interacts with a living organism and alters its activity.
- used interchangable with medication
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A: when manufacturer ready to market a drug,-> the United States
Adopted Name Council (USAN Council)
assigns the generic/ nonproprietary name
B: when drug is marketed then brand name/ proprietary name
A: generic name is also the official name that is listed
- B: the brand name is easily recognized
- -it begins with a capital letter
- - sometimes has a registration mark on upper right of name
- -different companies might have different names
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prescription drugs
-require a written order form from a healthcare provider (licensed for that from state)
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non-prescription/ over the counter (OTC) drugs
- -can be purchased without a prescription
- -assume do be safe for general population according to directions
- -some prescription drugs become non-prescription drugs
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drug classifications
- -looking it up must become second nature (you cannot know every drug)
- -learn common characteristics for a drug
- ->by usage
- ->by body system
- -> by chemical or pharmacological class (what the drug is made of)
- -a drug can act on more than one bodysystem (most do)
- -a drug can be in more than one classification
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What mechanisms promote drug quality and safety?
- until 20th centrury there were no regulations
- -> drug overdoses, addiction, ineffective drugs, dangerous drugs, nowadays illegal drugs were common
- now state and federal regulations -> regulations on administration, storage, ...
- teamwork to make drugs safer
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drug listings and directory
when in doubt, look it up !!
official standards for healthcare industry:
- -USP United States Pharmacopoeia
- (lists chemical and physical composition of each drug, rigorous standards of quality, permitted to use USP after name)
- (approved by FDA)
- (also a British Pharmacopoeia)
- -National Formulary(therapeutic value of drugs)
- (also a Canadian formulary)
- in addition
- -nursing drug books
- -PDR physician's desk reference
- -pharmacology texts
- -internet based formularies
- -pharmacist
- -medication package inserts
- -institutional medication policies and proce
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nurse practice act
in most states a nurse cannot prescribe or administer medications without an authorized provider's order -> license can be revoced
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us drug legislation
various and federal agencies regulate the manufacture and sale of medications
each state must confirm federal regulations
the states may want additional controls
local governments enact regulations regarding alcohol and tobacco
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regulation of controlled substances
controlled substances
- -either limited medical use of
- -high potential for abuse and addiction
- -CSA Controlled Substances act: it is illegal to possess a controlled substance without a prescription
- must be stored, handled, diposed of, administered according to regulations by DEA Drug Enforcement Agency (only prescribers with a national provider identification number have the authority to prescribe controlled substances) -facilities must lock them in a drawer within a locked area = double locking -facility must keep record of every dose (counting and tracking)
posession of narcotics for any other reason than for medical reasons is an offense, subject to severe penalty
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systems for storing and distributing
- stock supply/ bulk quantity
- (medications used very often, labeled and in a central location, requires to measure the dose every time it is needed (error possible), very cost effective)
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unit dose system
unit-dose-systemlocked medical card with drawers for each patient's medicationextra drawer for supplies like cups, syringes, ..., refills every shift or 24hours, limited amount of prn (according to patient need, stock medications also in cart),
unit dose=prescribed amount the patient needs at a single time eeach unit dose (usually one tblet) is individually packed and labeledpharmacist check each unit dose before sending it to the nursing unit
nurse will recheck med and dose when preparing
safes nursing timeis the safest method because of the double check method
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automated despensing system
- automated dispensing system similar to the unit-dose system
- locked card with frequently used meds
- database checks counts and has med prescription
- each nurse uses password to access
- allows immediate administration of newly prescribed drugs, controlled substances and emergency meds because nurse does not need pharmacy to fill prescription
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self administration
- at times patients will self administer meds while in hospital
- stored in individual containers at bed side
- remind guest to tell when drug is taken
- promotes independence
- evaluate before discharge
- some institutions do not allow self administration-> check policies
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What is pharmacokinetics?
pharmacokinetics refers to the absorption, distribution, metabolism and excretion of the drug
these 4 processes determine intensity, duration , action
each drug has unique pharmokinetic characteristics
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What factors affect drug absorption ( movement from the site of administration into the bloodstream)?
-absorption detemines when a drug becomes available to action, metabolism and excretion
- -depends on route of administration
- - form of the drug
- -drug solubility
- -effects of pH
- -bloodflow to the area/ body surface area
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route of administration
-either local (site of application) or systemic effect (must be absorbed into bloodstream before transported to distant location)
-entering of circulation either through injection into vein or absorption from other areas (e.g. muscle, stomach lining, mucous membranes, skin)
-> drugs manufactured for specific route (e.g. oral, sublingual, buccal, inhalant, topical, enteral, parenteral) and absorbed at different rates depending on route
-> form of drug determines the route
-> choice of route is crucial in determining of suitability for patient (e.g. no oral drug when vomiting, diarrhea...)
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capsule
- -gelationous container that holds liquid, powder or oil form of drug
- -when swalloed the gelatine container dissolves in the gastric juices
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pill
this term is rarely used, use tablet
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tablet
- -powdered drug in compressed form
- -brakes up into powder in stomach
- -most common oral preparation
- -enteric-coated tablets have an acid insoluble coating->disintegrate in alkaline secretions of small intestine
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time-released tablet or capsule
formulated so that it does not dissolve all at once, gradually releases meds over a few hours
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elixir
liquid containing water + about 25% alcohol that is sweetened with volatile oils, not as sticky or sweet as syrups
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extract
very concentrated form of a drug made from animals or vegetables, may be syrupy liquid or powder
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fluid extract
- alcohol based solution of a drug from a vegetable source
- the most concentrated of the fluid preparation
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spirits
concentrated alcohol-based solution of a volatile (easily evaporated) substance or oil
contains larger amounts of the substance than could be dissolved in water
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oral route
advantages/ disadvantages
- advantages:
- -convenient,
- -sterility not needed
- -economical
- -noninvasive, low-risk procedure
- -easy to administer, good self-administration
- -capsule can mask unpleasant taste of drug
- -capsule can be time-release
- disadvantage:
- -unpleasant taste may cause non compliance
- -may irritate gastric mucosa
- -patient must be conscious
- -digestive juices may destroy drug
- -cannot use if patient has nausea, vomiting, decreased gastric mobility
- -cannot if difficulties swallowing
- -potential for aspiration
- -may be harmful for teeth
- -onset of action is slow
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solubility of the drug
refers to the ability of a drug to transform into a liquid form that can be absorbed by the bloodstream.
enteric-coated drugs dissolve in small intestine-> delayed action of meds -> decrease of irritating effects on stomach
timed-release/ sustained release meds dissolve slowly, not all at once
for absorbtion drug must be water soluble or at least partially lipid soluble:
water soluble: drug must be water soluble in order to be absorbed by the aqueous (watery) contents of the GI tract
- lipid soluble:
- depends partly on the chemical structure of drug and partly on the site of absorption (lipid soluble drugs can penetrate lipid-rich cell membranes (watersoluble ones cannot) -> they can cross the blood-brain barrier and can cause sedation
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effects of pH and Ionization
- -pH effects absorption of drug
- -acid content of stomach adis in transporting drug across mucous membrane -acidic meds like aspirin are better absorbed here than alkaline/ basic like sodium bicarbonate.
-In solution some drugs ar ionized (electrically charged), some nonionized.
ionized -> lipid insoluble -> cnnot pass easily through cell membranes
transformation from ionized/ unionized can easily be done depending on pH of environment e.g. aspirin in acidic stomach juice-> most molecules remain nonionized
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blood flow to the area
-drugs absorbed rapidly where blood flow is greatest (e.g. oral mucous membrane)
-area with poor vascular supply experience delayed absorption (e.g. skin)
-excessive exercise draws blood away from the stomach and intestines to the muscles
-person in shock has poor peripheral circulation (blood flow to extremities).
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how are drugs distributed throughout the body?
- transportation of drug through body fluids (usually blood)
- as blood flows to all bodyparts the drug can theoreticcal produce effects anywhere
- rate of distribution depends on
- -local blood flow in target area
- -permeability of capillaries to the drug's molecules
- -protein binding capacity of the drug
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local blood flow
-bloos supply of target site effects distribution (difficult to skin, toes, ->blood vessels are small)
- vasodilation: application of warmth to injection site, fever, rest
-vasoconstriction: shock, chilling of the body
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membrane permeability
the capillary network and membranes (tightly paccked endothelial cells) in some areas of the body act as barriers
e.g. blood brain barrier allow only the passing of drugs that are lipidsoluble and not tightly bound to plasma proteins
- many antibiotics only watersoluble -not able to reach central nervous system
- -> but can be injected into inthratecally (via spinal canal) into cerebrospinal fluid
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protein binding capacity
-drugs tendency to bind to plasma protein effects distribution
-only unbound/ free drug molecules cand produce pharmacological effects, only free molecules can be metabolized and excreted
-malnourishment and liver desease reduce amount of protein (serum albumin) available for binding
-given percentage of a drug binds to plasma proteins, the remainder are free
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how are drugs metabolized in the body?
metabolism/ biotransformation
= chemical inactivatio of a drug thorug conversion to a more watersoluble coumpound or metabolites that can be excreted
- at site of action drug is metabolized (mainly liver but also kidney, blood plasma, intestinal mucosa, lungs)
-liver disease or aging _> drug metabolized more slowly->toxic levels may accumulate
-disease states effect metabolism e.g. diabetes patients do not metabolize sugar effectively-> no elixirs with high sugar content
-first pass effect -> many oral medication are absorbed and directed through the liver before reaching the active site-> that is why oral medication formulated with a higher concentration than prenteral medications
-some drugs are given parenterally so they can get to the site of action without passing the liver first
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how are drugs excreted from the body?
- a drug continous to have effects in the body until excreted
for excretion to occur the drug has to be removed from the sites of action and eliminated by the body
-drug may be metabolized completely, partially, or not at all when excreted
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common organs of excretion
kidneys (primary site of excretion, needs adequate fluid, decreased renal function/ see elevated creatinine level-> check toxicity-> adjusted med dosing)
- liver and GI tract some drugs are broken down by liver and excreted through GI tract. If drugs are reabsorbed=enterohepatic recirculation,
- -increased peristalsis e.g. diarrhea accelerates excretion,
- -inactivity, poor diet, decreased peristalsis-> delay excretion-> increase in drug effect
- lungs most drugs removed by the lungs are not metabolized first. gases and volatile liquids (e.g. general anesthetics) administered by inhalation usually are removed by exhalation. alcohol and others can be excreted by lungs,
- -deep breathing promotes excretion
- -decrease cardiac output (e.g. shock) and hypoventilation (e.g. pain) decrease excretion
- exocrine glands (sweat and salivary)
- -drugs excreted in saliva are usually swallowed
- -elimination of metabolites in sweat frequently responsible for dermatitis
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concepts relevant to drug effectiveness
- -onset, peak, duration of drug action
- -therapeutic range
- -bio availability of the drug
- -concentration of the drug at target sites
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onset of action
time needed for drug concentration to reach high enough blood level for effects to appear=minimum effective concentration
when concentration of medication is highest= peak action
period of time in which the medication has a pharmacological effect=duration of action
if drug level exceeds peak level=toxicity
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therapeutic range
- when giving multi-dose medication (e.g. antibiotic) -> goal: constant therapeutic blood level
- even after absorption stops-> distribution, metabolism, excretion continue
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therapeutic level
concentration of a drug in the blood serum that produces desired effect without toxicity
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therapeutic range
range of therapeutic concentration-> onset, peak level, through level (lowest concentration before next dose is due, measurement 30 min before next dose due)
- test: peak and through level-> helps to ensure the safety and effectiveness of certain drugs
- factors: drugs half-life, time between doses
monitor serum drug levels-> adjust dose and timing of dose
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biological half life
example: 50mg of a drug with a half-life of 6 hours
after 6 hours 25mg still in blood
after 12 hours 12.5 mg still inf blood
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what factors affect pharmacokinetics (effects on safety)?
- -age
- -weight
- -sex
- -pregnancy-> teratogenic drugs cause developmental defects
- -environment
- -route of administration
- -timing of administration
- -fluids pathological stages
- -genetic factors
- -psychological factors
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what is pharmacodynamics?
- stydy of how meds achieve effects at various sites in the body
- how specific drug moecules interact with target cells -> how biological responses occure
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anaphylactic reaction
- life-threatening reaction
- immediatly after administration
- constriction of bronchioles, edema of larynx and pharynx, shortness of breath , weezing
- severe hypotension
- immediate treatment: epinephrine, IV fluids, steroids, antihistamines, oxygen to intubation or ventilation
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medications frequently triggering allergic reactions
analgesics, anesthetics, antiinflammatory agents: morphine, codeine, ibuprofen, aspirin, tranquilizers, cocaine,
antiseizure drugs
antibiotics: penicillin, vancomycin, sufonamides
biological agents: enzymes, insulin,
diagnostic agents: iodinated media conrasts, IVP dye
other drugs: iron, histamines, dextran iodines,
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idiosyncratic reaction
- unexpected, abnormal or peculiar response
- (e.g. Benadryl causing excitement instead of drowsiness in some children)
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cumulative effect
increased response, build up of drug
-> body cannot metabolize drug before next dose
-> excretion is slowed by absorption is normal/rapid
->absorption is slowed
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how do drugs interact?
- drug interaction: one drug alters or modifies the action of the other drug,
- the more drugs are taken the higher the risk of drug interaction
antagonistic drug relationship: one drug decreases the resultant drug effect,
drug incompatilities: -> incompatible solution that should not be administered, mixed solution has a changed appearance, always check compatibilty chart before mixing of meds
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drugs may also interact with certain foods
high fat foods/ low in fiber -> delay stomach emptying and medication absorption by up to 2 hours
acidic citrus fruits and juices -> enhance absorption of iron. some, e.g. grapefruit interact in a antagonistic manner
carbonated soft drinks-> drug can dissolve faster, be neutralized, or change in absorption
dairy products ->taken with antibiotic like tetracycline decrease absorption
foods containing tyramine (aged, dried, fermented products-> consumed while taking monoamine oxidase (MAO) inhibitors may produce hypertensive crisis
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drug abuse/misuse
tolerance -> decreases response to repeated doses of drug
drug dependence -> compulsive patterns of drug use , lifestyle centers taking the drug
drug misuse ->nonspecific, indiscriminate, improper use of drugs incl. alcohol. often frequently misuse laxative (esp. elderly), aspirin, cough and cold meds
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drug abuse
inappropriate intake of a substance by amount, type, situation, continuously or periodically, my or may not lead to dependence
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illicit drugs
- = street drugs
- are sold illegally,
- many are prescription drugs,
- for mood altering effects
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units
always read lable to know how many units in one ml (U100 = 100 units per ml)
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standard written prescription
- without renewal date
- until alter or discontinue
- or specific stop date (has to be renewed)
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automatic stop dates
- protocols that that hospitals use
- most narcotic prescriptions only 7 days
- after that new prescription is needed
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STAT
single dose of drug has to be given immediatly and only once
- stat = now
- should appear on prescription
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Single/ one time prescription
medication is to be given only once at specified time
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Standing orders
officially accepted sets of prescriptions to be routinely applied for patients under certain conditions (e.g. drug allergies, postoperative patients...)
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prn prescription
- whenever the patient requires
- nurse together with patient determine when med has to be given
- specified
- -condition for which med is given
- -minimal time intercals between doses
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how are prescriptions communicated?
written
verbal: write with provider's name and own name, repeat prescription, spell medication name, avoid taking verbal prescription, only urgent situation
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error prevention technology
- -smart technology e.g. smart pumps
- -computerized prescriber order entry (CPOE) :
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What should I do if I commit a medication error?
1. immediatly take patient's vital signs and physical status
2. report findings to primary care provider
3. and notify nurse manager of unit
4. report event (risk management) according to policies
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what has to be done when/before administering meds?
1. perform assessments relevant to medication
- 2. review medication prescription and MAR ( medical administration record)
- clarify any differences
3.see reference for any unfamiliar medication
4. explain actions and side effects to patient
5.administer meds regarding to "rights of medication"
6.perform related interventions, for example fluids, timing of food,
7. assess vital signss
8. assess for contraindications and side effects
9. evaluate and record patient's response to meds
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risk for injuries
- -polypharmacy
- -inconsistancy -> can be life threatening (e.g. Beta Blockers)
- -noncompliance (knowledge, finances, lack of symptoms, side effects, forgetfulness,
- -> always assess reasons)
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three checks
1. BEFORE pour, mix or draw up a medication, check it's label against MAR. Be sure name, route, dose, and time match the MAR entry
2. AFTER preparing the meds, and before returning/ discarding, check the label against the MAR entry again
3.AT THE BEDSIDE, check the medication again before actually administering it
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6 rights of medication
- RIGHT
- 1. medication (check 3 times)
2. patient (check bracelet)
3. dose (check calculations, decimal point, doublecheck by collegue...)
4. route (includes right site sonsidering age and medicak condition)
5. time (never assume patient received meds as scheduled if not documented)
6. documentation (immediatly on patient's MAR; name of meds, dose, route, date and time, administerin nurse's name and initials)
7. reason (not giving unnecessary meds)
8. right to know (tell patient name of meds and why, action, side effects)
- 9. right to refuse
- (the patient has always the right to refuse meds, regardless of the reasons and consequences)
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right documentation
if medication is not given document this on MAR together with reason e.g. refusal, NPO for surgery,
when giving prn meds also include assessment and time when med was given, then later record patient's response to drug
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instillation
placing medication into a body cavity (e.g.eye drops)
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irrigation
washing out a body cavity with a steady stream of fluid or water (sterile water, saline, sntiseptic solution flushed into eyes, ears, throat, vagina, rectum, urinary tract)
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parenteral medications
- injected via
- intradermal
- subcutaneous
- intramuscular
- intravenous route.
- -absorbed faster than by other routes
- -results more predictable
- -dosage more accurately
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Gauge
- inside diameter of needle lumen
- numbered 14 to 30
- the smaller the gauge number the larger the diameter ( 16 gauge needle is larger then 20 gauge needle)
- choose size according to
- -patient's size
- -skin condition
- -viscosity of medication
- -speed of administration desired
smaller(25-30) less trauma, pain (frequent or longterm injections e.g. insulin)
larger (14-18 gauge) blood and more viscous meds, to mix intravenous meds, repid infusion of IV meds
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Bevel
- slanted tip with narrow slit
- -long bevel tip is sharper and narrower-> causes less discomfort during injection
- -long bevels usually for subcutaneous and intramuscular injections
- short bevels for intradermal and IV injections
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needle length
- 3/8 to 3 inch
- longer for intramuscular
- ahorter for intradermal
- varies depending on patient
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filter needles/filter straws
- used to trap rubber or glass fragments from vial or ampule
- replace filter needle with regular needle before injecting
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syringes
-barrel, plunger, syringe tip
-do not touch inside of barrel, hub, shft of the plunge, needle
syringe tip
- luer-lock-> twist on
- non-lue-lock-> slip on
fits onto needle hub
- usually 2-3ml syringe for intramuscular
- >5ml for IV administration, instillation, irrigation
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intradermal injection
- into dermis (layer beneath skin surface)
- commonly used for allergy and tuberculosis testing
- nondominant for Tb
- dominant arm,chest, upper back for all other tests
- only small amounts about 0.1ml
- 1ml syringe
- short, small needle (26-28 gauge)
- angel 5 to 15 degree
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subcutaneous injection
- into subcutaneous tissue (layer of fat below dermis)
- absorption slower than intramuscular
- site of arm and abdomen faster
- thigh and buttock slower absorption
- aspiration step not needed
- avoid abnormal sites (scars, birthmarks, burns, etc.), sites with prominent bones, large underlying vessels,
- or nerves
- abdominal not nearer than 2 inched (5cm) from umbilicus
- not cloeser to each other than 1 inch, rotate
- short, small needle-> long enough to penetrate subcutaneous layer, short enough to not get into muscle
- depending on amount of adipose patient got
- usually 5/8 needle, some even smaller
- standard: 45 angle, regular needle
- when choosing smaller needle use 90 degree angle
- obese: large needle (e.g. 1 nch) and 90 degree angle
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administering heparin
- subcutaneously
- accidently given into muscle will cause brusing and pain
- check coagulation studies before giving
1. add 0.2ml of air after drawing up correct dose
2.do not massage site after injection
3.never aspirate, will increase bruising
4.with low molecular weight heparinalternate between left/righ antero/posterolateral abdominal wall
5.inject whole length of needleinto skin fold held between thumb and forefonger (hold
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intramuscular injection
- into muscle tissue
- faster absorption than subcutaneous
- can tolerate more fluid (3-4ml into large vastus lateralis and ventrogluteal muscle)
- no more than 0.5-1ml in regular deltoid muscle
- aspirate
- deltoid for adults, anterolateral thigh for infants)
- vastus lateralis,
- ventrogluteal (whenever possible)
- deltoid
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ventrogluteal muscle - site of choice
- for adults and walking young children
- involves gluteus nedius and gluteus miminimus muscle
- safest and least painful
- but check, some meds given into deltoid
- feels hard
- look up how to locate it
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dorsogluteal site
- do not use
- risk of hitting nerve /bloodvessel
- do not use for infants and children
- sciatic nerve-> paralysis possible
- ...
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deltoid site
- middle third of upper arm
- meds absorbed rapidly
- use only for small amounts up to 1ml
- do no use in infants
- expose entire upper arm and shoulder
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vastus lateralis site
- located in the anterolateral thigh
- preferred site for young infants, particularly before walking
- drugs rapidly absorbed
- larger volume of meds possible
- not near any large blood vessels or nerves
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rectus fermoris
- not longer recommended to use this site
- do not use for infants or children
- painful
- use shorter needle
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choosing intramuscular needle
- standard: 1.5 inch
- deltoid: maybe 1 inch needle with 23-25gauge
- obese: may be as long as 3 inch
- angle: 90 degree
choose needle according to patient, site, medication
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z track technique
use larger muscle, hold needle inside, steady, 10seconds?
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