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Chapter 20
Pharmacology
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Objectives
1. Recognize common definitions and nomenclature
associated with pharmacology.
2. Recognize the various classifications of drugs.
3. Describe the actions, indications, and precautions
related to various drugs.
4. List the five rights of drug administration.
5. List the methods of drug administration.
6. Prepare intravenous drugs for injection.
7. Perform venipuncture using appropriate universal
precautions.
8. Describe documentation procedures related to drug
administration.
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Pharmacology
• A drug is any chemical substance that produces
a biologic response in a living system.
• A drug is a substance used as medicine to aid in
the diagnosis, treatment, or prevention of
disease.
• The science concerned with the origin, nature,
effects, and uses of drugs is called
pharmacology.
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Physicians’ Desk Reference
• Commonly called PDR
• Annual publication that contains current product
information
• Pages are color coded and list drugs by both
their generic and their brand names
• PDR gives the accepted uses, side effects,
contraindications, and doses for available
drugs
• IF PDR unavailable, speak with pharmacist
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Drug Classifications and Dosages
• Classification by Action
• Classification by Legal name
• Dosage Forms
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Drug Profile
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Chemical composition
Absorption characteristics
Distribution characteristics
Metabolic characteristics
Elimination characteristics
Indications, actions, and effects
Interactions and contraindications
Patient reactions
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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2
Pharmacokinetics Process
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•
•
•
Absorption
Distribution
Metabolism
Excretion
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Drug Absorption
• How it gets into the circulatory system
• Bioavailability is the amount of drug that
reaches systemic circulation
• Drugs must be absorbed in order to begin
activity
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Drug Distribution
• Absorption of drug into the body and its
travel to the intended site of activity via
circulatory system
• Affected by several factors
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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3
Drug Metabolism
(Biotransformation)
• The metabolism of the drug by altering its
chemical structure
• Most drugs metabolized by liver in the
hepatic microsomal enzyme system
• Biotransformation occurs through four
major pathways
• Metabolism affected by many factors
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Factors That Influence
Drug Action
•
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Patient Age
Health Status
Time of Day
Emotional State
Other Drugs in the Body
Genetic Variations
Disease State of the Body
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Drug Excretion
• Removal of drug from the body
• Principally performed by the kidneys
• Also occurs by way of:
– Biliary tract
– Lungs
– Sweat
– Saliva
– Breast milk
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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4
Classes of Drug Reactions
•Allergic
•Idiosyncratic
•Iatrogenic
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Osmolality
• The measure of the total number of
particles in solution per kilogram of water
• Great biologic significance
• Most adverse reactions to contrast are a
result of the osmolality of the agent
• Ionic contrast agents are HOCM
• Nonionic contrast agents are typically
LOCM and quite popular
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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When Administering Drugs
You
Must:
1. Record Name of Drug
2. Record Route of
Administration
3. Record Time of
Administration
4. Record Patient’s
Reaction to the Drug
You Administered
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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5
Factors That Influence
Drug Action
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Patient Age
Health Status
Time of Day
Emotional State
Other Drugs in the Body
Genetic Variations
Disease State of the Body
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Rights of Drug Administration
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Right Drug
Right Amount
Right Patient
Right Time
Right Route
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Drug Administration Routes
• Enteral Routes
– Oral
– Rectal
– Vaginal
• Parenteral
Routes
– Intramuscular
– Intravenous
– Subcutaneous
– Intradermal
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Drug Administration Supplies
• Parenteral administration uses
syringes and needles
• An angiocath is a safer device
compared with other systems
to use when performing
venipuncture
• Needle diameters expressed in
gauges
• Drugs intended for use by
parenteral administration are
packaged in two different kinds
of containers
Insert Fig 20-1 here
FIG. 20-1 Parts of a syringe.
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Routes of Drug Administration
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Oral
Sublingual
Topical
Rectal
Parenteral
Ampule
Vial
Prefilled
syringe
Infusion Drip
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Parenteral Administration
• Drugs that are injected
have a rapid onset of
action because they are
absorbed directly into the
bloodstream
• All forms of parenteral
administration require the
use of a needle, syringe,
and container
• Requires aseptic
technique
• Four routes of injection
Insert Fig 20-3 here
FIG. 20-3 Parts of a needle.
Insert Fig 20-5 here
FIG. 20-5 Needle bevels. Long or regular bevels are usually used
for intramuscular or subcutaneous injections. Short bevels are
commonly used for intravenous injections.
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Parenteral Injections
Subcutaneous Injection
Insert Fig 20-10 here
FIG. 20-10 Proper needle placement for injection into the subcutaneous
tissue. The needle is inserted at a 45-degree angle.
Intramuscular Injection
Insert Fig 20-11 here
FIG. 20-11 Proper needle placement for injection into the muscle
tissue. The needle is inserted at a 90-degree angle.
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Venipuncture
• Drug is placed directly into a
vein.
• Needle length and gauge
depend on the viscosity of the
drug, the site selected, and the
specific method of injection.
• While injecting, observe site for
extravasation or infiltration.
• If extravasation occurs, the first
step is to remove the needle,
apply pressure to the injection
site, and apply warm moist heat
to relieve the discomfort.
FIG. 20-12 Sites commonly used for venipuncture.
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Drip Infusion
• Involves infusion via
an IV assembly
• Used for large
volumes of fluid
administered
• Patients often come
with IV pumps
• Pay attention to the IV
pump alarms
Insert Fig 20-13 D here
FIG. 20-13 Drip infusion.
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Characteristics of Valid Prescription
• Patient name, room number, address, and
ID number
• Drug name
• Dosage
• Dosage form
• Route of administration
• Date order is written
• Signature of prescriber
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Conclusion
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The radiologic technologist is expected to have a basic knowledge of
pharmacology to prepare and administer drugs under the supervision of a
licensed practitioner.
The PDR is a reference, usually found in the radiology department, that lists
drugs by both generic and trade names.
Some common dosage forms include tablets, capsules, suppositories,
solutions, suspensions, and transdermal patches.
The radiologic technologist should be familiar with the actions and
precautions associated with commonly used drugs.
The golden rules of drug administration should always be followed when
preparing to administer or when assisting with drug administration.
Numerous factors affect the patient’s response to a drug, which may be
undesirable.
After administration, relevant information should be recorded on the
patient’s chart.
Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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