Pharmacology & Contrast Media

Is the study of drug actions on and interactions with living organisms

Pharmacology

Investigates the metabolic, distribution, and absorption processes of the drug within the body

Pharmacokinetics

Deals with the specific effects or actions of a particular drug

Pharmacodynamics

When a drug is introduced into the body it’s action usually begins when it attaches itself to a what?

Specific target cell

When a drug binds itself to the receptors on specific cells and produce an effect

Agonist (causes an action- activates the receptor)

When drugs binds with certain receptors and prevent an action from happening

Antagonists (blocks an action- blocks the receptors)

Produce a wide variety of effects to the patient

Systemic medications (prescription drugs)

Are usually administered at a specific site or injected into tissues only in that particular area

Local medications

Routes of Drug Administration that involves the esophagus, stomach & Gi

Enteral Routes

Methods for enteral routes

Oral

Sublingual (dissolving under tongue)

Rectal

Routes of Drug Administration Parenteral Routes means what?

non-oral

methods for Parenteral Routes

Intradermal
Subcutaneous
Intramuscular
Intravenous
Intra-arterial
Intrathecal (spinal cord)

Needle angulation for intramuscular

90 degrees

Needle angulation for subcutaneous

45 degrees

Needle angulation for intravenous

25 degrees

Needle angulation for Intradermal

10-15 degrees

Used for local treatment of skin ailments

Topical Routes

When administering drugs Six Rights

Right Patient

Right Drug

Right Dosage

Right Route

Right Time

Right Documentation

Is the process of inserting a needle into a vein, usually to withdraw blood for analysis

Venipuncture

The process of venipuncture can be achieved with the use of…

syringe or Vacutainer system

What is commonly used in the imaging department when injecting contrast for radiographic examinations

Syringe

most commonly used in various types of analysis will be performed requiring the collection of more than one sample

Vacutainer system

Common sites for the insertion of the needle

basilic vein,

median cubital vein

cephalic vein

median antebrachial vein

Most common site for venipuncture?

median cubital vein

What should be taken before and at frequent intervals during IV drug administration

Pulse rate & blood pressure

What locks is a venous catheter that is left in place in the vein for a designated period of time but is not attached to IV tubing

Heparin & Saline

Medications (including contrast agents) may be given by

Bolus & infusion

is a designated amount of drug that is administered at one time

Bolus

usually refers to a larger amount of a drug, fluid, or fluid containing a drug or electrolytes that is administered over a longer period of time.

Infusion

A substance introduced into the body to better visualize an organ or body part

Contrast Media

The selection of a contrast medium is governed by five important factors:

It must be non-toxic.

It must produce adequate contrast.

It must be of suitable viscosity.

It must have suitable persistence.

Miscibility or immiscibility.

What are the classes of contrast Media

Positive & Negative

Which contrast media has Low atomic weight, absorb less radiation & produces greater IR (DD) exposure on the radiograph.

Negative contrast

What is the atomic number & weight of Oxygen?

number→8

weight→16

What is the atomic number & weight of Nitrogen?

number→7

weight→14

Which negative contrast media is dangerous b/c of emboli?

Air & O2

Which negatively contrast media are rapidly absorbed and do not pose a threat of emboli (blocking of artery)?

CO2 & Nitrogen

B/c of the rapid absorption of CO2 & nitrogen what is it that they don’t do when a series of radiographs are taken?

do not enhance radiography

what type of contrast media causes an increase in absorption of x-rays

Positive contrast media

What is the atomic number & weight of Iodine?

number→53

weight→126

What is the atomic number & weight of Barium?

number→56

weight→137

Aside from Iodine & Barium what’s another positive contrast medium used?

GBCA. (Gadolinium based contrast agent)

The four physical states of positive contrast media are ?

Oils

Powered/Granules

Liquids

Tablets

Example of a oil contrast media

Pantopaque (myelograms) & dionosil (bronchogram)

Example of a powder/granules contrast media

Barium sulfate (G.I.) & orografin calcium

Example of a liquid contrast media

Hypaque (I.V.P.)

Example of a tablet contrast media

Bisacodyl (G.B.)

Types of Positive Contrast Media

Insoluble

Soluble

What’s an example of an insoluble contrast medium & what’s it most commonly used for?

Barium Sulfate – used for most G.I. exams

What are the different types of soluble media?

Water Soluble Media (carried to the body)

Fat Soluble Media (stored by the body in its tissues)

Best for direct injection into the circulatory system because it is readily miscible with blood and prevents formation of emboli (It is readily excreted)

Water Soluble Media

A Water Soluble Media causes what to occur?

An increase of blood in the vessels.

An increase in blood pressure.

A draining of fluid from the body (dehydration) of the patient.

Most common concentration of water soluble media is what?

60% to 90%

Water soluble media should not be used w/ which PTs?

Patient who are dehydrated

Patients in a precarious state (unstable conditions) of cardiac and/or retaining fluids

Water soluble media is used most commonly for

Urography

Angiography

C.T. studies

Best for increased IR (DD) Exposure and nondiffusibility are required

Fat (Oily) Soluble Media

Exams such as bronchograms, lymphangiograms, and salpingiograms frequently will produce embolism for what reason?

Due to oily base since there is little or no absorption

Most contrast media are

Diatrizoates

Iothalamates

There are sodium and methylglucamine (meglumine) salts of ….

diatrizoates and iothalamates

diatrizoates and iothalamates contrast media may be …

Pure sodium.

Pure meglumine.

A mixture of both.

Sodium salts are more … than meglumine

Toxic

Meglumine salts have greater…

Viscosity

Salts of organic iodine compounds have greater

Viscosity

Iodine is mainly used because…

Availability

Atomic number

Exchangeability with other ions (chemically attached to different molecules)

Characteristics of Contrast Medias

Miscibility

Persistence

Viscosity

Must be easily and rapidly absorbed so as not to produce a contrast media embolism (Mixes well)

Miscibility

Refers to the excretion time. Must be rapid in order to prevent
emboli. Must remain in long enough to produce necessary radiographs

Persistence

What’s an example of a media that has persistence?

Oil based media, it remains and is not excreted

Is the density of the contrast media

Viscosity

Low viscosity presents as what and High viscosity presents as?

Low→ Thin

High→ Thick

As iodine content or concentration increases

So does viscosity

What is a factor to taken into consideration when small bore cathers are used?

viscosity

The viscosity and toxicity changes causes secondary effect of

Platelet aggregation.

Blood pressure changes.

Pulse rate changes.

Cardiac output (amount of blood heart pumps)

Secondary effects depend upon:

Volume of medium injected

Speed of injection

Media toxicity

Media viscosity

Contrast Reactions

Nausea

Flushing

Sneezing

Shivering

Chest pain

Facial swelling

Itching

Urticaria

Dypsnea

Drop in BP

LOC

Convulsions

Cardiac Arrest
• Edema

The pressure a solution exerts on a semipermeable membrane, which separates a solution from a solute. Expressed as milliosmols per kilogram of solution.

Osmolarity

The pressure a solution exerts on a semipermeable membrane, which separates a solution from a solute. Expressed as milliosmols per kilogram of water.

Osmolality

the movement of water or other solvent molecules through a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration

Osmosis

Having the same concentration of solute as another solution.

Isotonic

Having a greater concentration of solute than another solution.

Hypertonic

Having less of a concentration of solute than another solution.

Hypotonic

the accidental leakage of a fluid—such as blood, lymph, or an intravenous medication—from a blood vessel or tube into the surrounding tissue

Extravasation

a sudden reflex that causes your heart rate and blood pressure to drop, leading to reduced blood flow to the brain and often resulting in fainting

Vasovagal reaction

a selective, protective border of cells that lines the blood vessels in the brain and keeps harmful substances out while letting vital nutrients in

Blood-brain barrier