CH. 12 - PHARMACOLOGY FOR RADIOGRAPHERS

What is pharmacology?

study of drug actions and interactions with living organisms

What are drugs that are considered safe for self-administration called?

over-the-counter

proprietary or trade drug names

assigned by manufacturer

chemical drug name

exact chemical formula of a drug and always remains the same

generic drug name

name given to a drug before its official approval for use and assigned by the U.S. adopted name council

ex- DIazepam - Valium

depressants (chemical group)

slow the function of the central nervous system

ex) alcohol, opiates, and tranquilizers

stimulants (chemical group)

speed up the CNS, increased heart rate, increase BP, and body temp

ex) caffeine, nicotine, and amphetamines

hallucinogens (chemical group)

distort the sense of what is real. may experience panic or paranoia

ex) ketamine “special K” LCD lysergic acid diethylamide

What are pharmacokinetics?

processes that control absorption, distribution, metabolism, and excretion of drug by the body

absorption

needs to be in the blood stream-bioavailability varies on person and drug including amount used

passive diffusion/transport

ability to pass the cell membrane- from a higher to lower concentration

lipid solubility

concentration on both sides are equal (most important)

active transport

requires energy from enzymes or proteins to carry drug into the cell

Where are drugs taken PO (oral) absorbed?

in the small intenstine

What is the first pass effect?

drug that is absorbed by the liver from the stomach then into the systemic circulation. partially metabolized

What drugs avoid the first pass effect?

drugs that are absorbed by vaginal, sublingual, or parenteral- directly into the systemic circulation

What is enterohepatic recycling?

allows the drug to persist in the body for long periods

distribution

affinity for lipoid or aquous tissues effects result

• moves quicker to heart, liver, and kidneys

• free drugs act on a cell. plasma protein inactivates drugs

• persons health status effects distribution

metabolism

drug is chemically altered by the bodily function

• reduced lipid solubility allowing body to ready the drug for excretion

• adverse reaction - change in metabolic state creating build up for drug

excretion

drugs filtered out of the body primarily by the kidneys

half-life

time it takes for a 50% decrease in a drugs presence in the body

clearance rate

drugs removal from the body

pharmacodynamics

study or method or mechanism of drug action on living tissues or the response of tissues to chemical agents at various sites in the body

How do drugs alter body?

alter BP, alter heart rate, alter urinary output, alter function of the CNS and PNS, alter changes in all other body systems

What is a drug receptor?

max effect of drug

What is drug affinity?

how well the drug is going to work

What is drug efficacy?

strong affinity at receptor site; drug effect is low

What is drug molecular structure?

drug determines the affinity of receptors

What is pharmacogenomics?

branch of pharmacology that studies the effect of genetic factors as they are related to drug reactions

metoprolol

lowers heart rate

• beta blocker for high blood pressure

vsodilators

increase blood flow

• nitroglycerin coronary heart studies in CT

antihistamine

prevents respiratory distress- opens bronchioles

• benadryl- antihistamine- helps prevent anaphylaxis

• epinephrine- opens up narrow passage ways, long term effect

negative contrast (radiolucent)

• air (lungs) nothing to absorb the xray energy

• organ appears darker on image

positive contrast (radiopqaue)

insoluble (barium sulfate) and water soluble (gastroview)

• organ absorbs the xray energy. appears white or many shades of gray (dense)

radionuclides

emit radiation and used in nuclear medicine

characteristics of negative contrast

• low atomic weight

• decrease organ density

• absorbs less radiation photons

• greater image density

• radiolucent

• rapidly absorbed by the body

positive contrast characteristics

• high atomic weight

• increase organ density

• absorbs more radiation

• decreased image density

• radiopaque

• readily excreted unchanged through the liver or kidneys

• relatively nontoxic

gastroview (iodine) contrast media

• atomic number 53

• eater soluble- clear liquid solution

• absorbs into abdominal cavity; into the tissues; surgical preference

barium sulfate (NO IODINE)

• doesn’t dissolve, suspends in solution

• positive contrast media

• atomic number 56

• barium is a metal

ionic contrast media (HOCM)

• one cation and one anion in the salty solution

• higher probability of allergic reactions

• 50% osmotic effect

non-ionic contrast media (LOCM)

• closer to human plasma. cation has been removed; replaced by hydroxyl

• most common

appropriateness of IV contrast exam

• patient history is important to IV contrast administration

• ACR publication to advise MD, PA, NP for ordering exams

What are possible contraindictions when using IV contrast media that present an increased risk for an adverse reaction?

• previous reactions to contrast

• asthma

• allergies

• heart disease

• renal disease

Why wouldn’t you give a patient IODINE contrast media?

• known allergic reaction; with exception to pre medication

• no MD order

• renal function low, GFR below 30

  • radiologist or md order may ask for hydration to complete the exam

  • non contrast x ray exam may be done because labs are too low

IV contrast reactions

• normal: feeling warm, flush, redness, nausea

• mild: sneeze, rash itching, hives, redness

• moderate: congestion, swelling, sneezing more often, gives, low blood pressure

• severe: low BP, hives, rash redness, sob, throat swelling, collapse, LOC

• delayed reactions: any of the above that progresses and becomes worse than before

When do reactions to contrast media occur most often?

when the medium is administered IV or intra-arterially

What body reactions are more toxic considered?

adverse reactions/idiosyncratic reactions

drug safety

• MD’s and RNs administer any needed medication to pt. RT assist

• RT are responsible for understanding and recognizing the symptoms and responses of IV and oral contrast

• drugs that may be given in response to any allergic reaction or change in patients condition

• seizure

• vaso vagal

• mild, moderate, severe allergic reactions

PDART

correct patient

correct dose

correct amount

correct route

correct time

bolus

drugs used to treat most illnesses are administered in small dosages at selected intervals, whereas contrast media are often administered in a large dose at one time

isotonic

most drugs used for treating illness that are administered intravascularly

enteral route

PO, sublingual, cheek, rectal

most efficient and most cost-effective method of drug administration

route is used if the drug will not be destroyed by gastric secretions and when slower absorption and longer duration of drug activity are desired

sublingual drug

placed under tongue and dissolves completely

must not eat or drink until drug dissolves

not to be swallowed or chewed

buccal route

placed against the mucous membranes of the cheek in upper or lower jaw

must remain until dissolves

drugs used this route are used for local effect and are drugs such as lozenges

rectum route

patient is nauseated and unable to retain oral drugs

tube/catheter administration

through stomach, small bowel, large bowel, or bladder

inhalation administration

into the mouth or nasal passage

most advantageous method to deliver medication to the lungs

disadvantages bc airway symptoms that will not allow the patient to inhale deeply enough to get a full dose

topical administration

through skin for local treatment of lesions or skin conditions, to eyes/nose/throat, vagina/recturm, ti the skin for intended systemic effect (transdermal application)

this route is most used for relief of chronic pain and for cardiac therapy

subcutaneous (parenteral route)

below dermis and epidermis layers of skin

location: upper arm, abdomen, front of the thigh, upper area of the buttock behind the hip

intramuscular (parenteral route)

drugs can be injected at body muscles such as deltoid, rectus femoris, ventrogluteal or dorsogluteal

sciatic nerve and superior gluteal artery pose a risk

ID

longest absorption rate of all parenteral routes

injection into dermis

used for TB tests or allergies

if contrast allergy testing is performed, ID injection is used

IV

effect of drug is immediate bc goes into bloodsteam

common locations: median basilic or cephalic veins in upper extremity

intrathecal

spinal cord

ex: lumbar puncture

intra-arterial

location: carotid artery or vertebral artery

used when thrombolytic drugs are needed with higher levels of concentration at the site of a thrombus

intraosseous

directly into bone marrow (sternum, clavicle, head of the humerous, distal remur, proximal tibia

used when IV infusion is not possible, goes directly into vascular syste,

intra-articular

injections are given into the joint space to show musculoskeletal anatomy and pathology

steroids use this method

Drugs that must bear the legend "caution: federal law prohibits dispensing without prescription" include the following

hypnotics and narcotics

Alternatives dietary and herbal supplements are classified as food, not drugs. T/F

true

The alternative name for Valium is diazepam. Valium is:

the trade name

Drugs given by mouth are generally given in larger doses. This is because:

they absorb more slowly

For a drug to reach its therapeutic effect more quickly, a physician might order:

an initial larger dose and later smaller dose

Marjorie Merriweather takes oral morphine for chronic pain. After taking the prescribed dosage for 2 weeks, she notices that it no longer seems to be controlling the pain. This reaction is called:

tolerance

Drug absorption varies from person to person. The efficiency of drug absorption is largely dependent on:

the absorptive surface available

Drugs given orally are not affected by the first-pass effect.

false

Contrast media are categorized as drugs. This is because they are absorbed into the systemic circulation and may produce a physiologic response on the body. T/F

true

The physiologic effect of a contrast agent on the patients body that may create an adverse reaction when administered is due to:

its osmolality particularly when it is higher than blood plasma

Expected side effects of contrast media administered by intravascular route are: (Circle all that apply)

feeling of warmth and flushing

metallic taste in mouth

A patient is receiving an intravenous contrast agent by bolus intravenous injection. The patient begins to complain of nausea, itching around his eyes, feeling dizzy, and a headache. The radiographer decides the patient is having:

a mild adverse reaction