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Pharmacology
Pharmacology
• The study of drugs and their actions
Reasons For Medication Use
• Diagnose
• Treatment
• Curative
• Lesson pain
• Prevent a disease or condition
Where Do Drugs Come
From?
• Plants
• Animals
• Minerals
• Laboratory
Chemical combinations
• Biotechnology
Genetics
Pharmacokinetics
Definition:
• The process a drug goes through upon
entering the body
• It involves the processes of absorption,
distribution, biotransformation (metabolism liver), and excretion
Pharmacokinetics
Absorption: For a drug to work , it must
be absorbed. It is absorbed at the site
where it is given. Once a drug reaches
the capillaries, it is taken into the
bloodstream. The rate of absorption
varies depending on the type of drug,
amount of the drug, route, and the
patient.
Pharmacokinetics Continued
Distribution: How the drug gets to its target
once it is in the bloodstream. Involves
circulation of the blood. Targets are cells in
tissue or organs.
Pharmacokinetics
Metabolism: How a drug is broken
down for excretion. Products of
breakdown are called metabolites.
Metabolites are rendered small, inactive
or less active before excretion occurs.
Metabolism usually occurs in the liver,
however can occur in the kidneys,
lungs, blood plasma, or intestinal
mucosa.
Pharmacokinetics
Excretion: A drug continues to have an
action until it is excreted by the body.
Kidneys generally are the excretory
route. Drugs can be excreted by saliva,
sweat, exhalation, breast milk, or feces
(poop).
Pharmacodynamics
Definition: Is the study of how a drug
acts on targeted cells.
Pharmacodynamics
Types of Drug Actions:
• Inhibitive or destructive
• Protection
• Supplementation
• Replacement
• Physiologic function (increase or
decrease)
Pharmacodynamics
Drug Effect or Action Theories:
• Agonists- Drug binds to a special receptor on a
target cell and produce the desired effect.
• Antagonists- Drug binds with a special receptor on
a target cell and prevent or inhibit a response.
• Non-specific- Neither agonists or antagonists.
These drugs gather on a cell’s membrane or go
through it and interfere with actual cell function
Pharmacodynamics
Timing of Drug Effects:
• Onset- time from when a drug is given
to when its effects first occur
• Peak Effect- when a drug is at its
maximum effect
• Duration- time from when drug effects
begin to when they stop
Routes of
Drug Administration
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Buccal(topical)
IM
Inhalation
Intra-articular
Intradermal/dermal
Intrathecal
Topical =‘s any epithelial
lined surface. Tongue,
rectally, cheek, vagina
etc
IV
Intracardiac
po/PO
SC/subq
sublingual (topical)
topical
Drug Preparations
• Forms of:
• solid
• semi-solid
• liquid
• gas/vapors
Abbreviations for PO or
Topical Administration
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Topical
cream
gtts (ear)
ung (ointment)
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PO
cap
gtts (oral/infants)
soln/sol
susp
tab
Frequency of Drugs
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Abbreviations:
bid
h/hr
prn/PRN
q
qd
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qh
q2h
qid
tid
stat
Administration Abbreviations
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AD (right ear)
AS
AU
OD
OS
OU
os
aa (of each)
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ad (towards)
RX
c (line over it)
dc/DC
KVO/TKO
npo/NPO
per
Nomenclature (Naming) of
Drugs
• Chemical name: chemical make-up of a drug
• Generic name: nonproprietary name given
to a drug by the developer of a drug
(acetaminophen, ibuprofen,
diphenhydramine)
• Trade or Brand name: Proprietary or
patented name of the manufacturer of the
drug (Tylenol, Motrin & Advil, Benedryl).
Manufacturing processes may differ slightly.
Legal Implications
(Federal)
• Pure Food and Drug Act
-Standards for US marketing
• Federal Food, Drug, and Cosmetic Act
-Regulations
-FDA approval
• Controlled Substances Act
-Established DEA
-Schedule of Controlled Substances:
C-I - Marijuana
C-IV – Phenobarbital (treat seizures)
C-II - Cocaine
C-V – antidiarrheal (low abuse rate)
C-III – anabolic steroids
The lower the # the higher the addiction/abuse potential
Legal Implications
(State)
• Regulate practice acts for ordering,
prescribing, and administration of
medications
• As a surgical technologist, we act as an
extension of the physician handling
drugs under their supervision
Legal Implications
(Local)
• May have specific guidelines for
medication administration in the
institution you are employed in
Metric System
• Meter = length
• Liter = capacity
• Gram = weight
Metric Prefixes
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Micro-one-millionth; 0.000001
Milli-one-thousandth; 0.001
Centi-one-hundredth; 0.01
Deci-one-tenth; 0.1
Unit-one;1.0
Deka-ten;10.0
Hecto-one-hundred;100.0
Kilo-one thousand;1000.0
Metric Equivalents
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Weight (gram)
1 gram=1000 milligrams
1 kilogram=1000 grams
1 ounce=30 grams
Capacity (liter)
1 liter=1000 milliliters
1000 liters=1 kiloliter
1 liter=1.06 quarts
• 1 quart=0.946 liters
• 1 milliliter weighs 1
gram
• 1 cubic centimeter (cc)
and 1 milliliter (ml) are
equal/same
• 1 liter=1000ml or cc
• 1 fl. oz.=30ml or cc
• 1 fl. dram=0.125fl. oz. or
4ml or cc
• 1 gallon=3.8 liters
Metric Equivalents
• Length (meter)
• 1 meter=1000mm=100cm=1.094 yd
• 1 yard=3 ft.=36 in.=0.9144 meters
• 1 in.=2.54 cm=25.4mm
• 1 micron
(micrometer)=0.001mm=0.000001 meter
Metric Abbreviations
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Gram-gm
Milligram-mg
Kilogram-kg
Liter-L
Milliliter-ml
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Cubic centimeter-cc
Meter-M
Millimeter-mm
Centimeter-cm
Temperature Measuring
• Fahrenheit (F)
Water freezes at 32°
Water boils at 212°
• Celsius (C) (centigrade)
Water freezes at 0°
Water boils at 100°
Converting C° to F° or F° to
C°
• Fahrenheit to Celsius
• 5/9 (F°-32) = C° ( or F -32 x 5 divided by 9 = C)
• Celsius to Fahrenheit
• 9/5 (C°)+32 = F° (or C x 9 divided by 5 + 32 =‘s F)
Dosage Calculations
• Formula:
• D (desired dose) x Q (quantity of dose on hand)
H (dose on hand) =‘s X
X = Amount to give/needed
• Example: Give 80mg of a drug from a
30ml stock bottle labeled “100mg per
1ml
• I know: 1ml=100mg
Need to give 80mg
• I do not know: Fraction of ml
that=80mg
• Common sense: If 1 ml of the solution
= 100mg of the drug, then the amount
given must be less than 1ml.
• Formula: D x Q = amt to give
H
• Solution: 80mg x 1ml=0.8 ml of sol.
100mg
• Proof: 80÷100=0.8
0.8x1=0.8
Standard Dilution Equations
• C1 x V1 = C2 x V2
• C = concentration in %
• V = volume
• Problem: Dr. needs 60 ml of ½%
contrast media. How much NACL and
how much media do you need to make
the required amount when you have 60
ml’s of 1% media?
• First we must convert the % to decimals
• 1/2% = 0.5
• 1 divided by 2 = 0.5
• You always do this when converting
percentages to decimals
• C1=1/2%=0.5 Concentration 1 (asked
for)
• C2=1% = Concentration 2 (given)
• V1=60ml Volume 1 (asked for)
• V2=x (? volume of saline)
• Formula: C1 x V1 = C2 x V2
• 0.5 x 60 =1 x x
• 30 = x
• So, You add x=30 ml’s of pure saline
• Need 60mlof 1% – 30ml’s = 30ml’s of 1% dye
solution and add 30ml’s saline to get 60ml of
0.5% dye solution
Standard Dilution Equation
• Doctor wants ½% lidocaine. You have 25ml
of 1% Lidocaine. How do you dilute it to the
proper strength?
• C1 (asked) x V1 (given) = C2 (given) x V2 (?)
• ½% x 25 = 1% x x
• 12.5= x
• 25ml lidocaine – 12.5mlof 1% lidocaine =
12.5ml lidocaine = 12.5ml saline =
½% or 0.5% lidocaine
Calculating mg Dose per kg
Body Weight
• Normal dose of propofol (an induction
drug used by anesthesia) is 2 mg per kg
for an adult
• Find initial dose for an adult weighing
150lbs
• Convert lbs. to kg (2.2 lbs. = 1kg)
• 150lbs. ÷ 2.2lbs. = 68kg
• 68kg x 2mg = 136mg
Calculating Child Dosages
• Clark’s Rule: Standard adult weight=150lbs
• Problem: If an adult receives 75mg of
Demerol, what would be an appropriate dose
for a child weighing 30lbs?
• Adult dose=75mg
• Child weighs 30lbs.
• Clark’s rule Standard adult weight = 150lbs.
• Common sense: child is smaller, dose will be
less than 75mg
• Formula:
Child’s weight x Adult dose = Child’s dose
Adult weight
• Solution:
• 30lbs. x 75mg = 15mg of Demerol
150lbs
Mixing Medications
• Do not mix drugs unless you know for certain that
they are compatible together
• If a compatibility is questioned direct the question to
the pharmacist to be certain before mixing
• Mixing drugs that are incompatible can result in
decreased or increased efficacy,
precipitates/crystallization of the drugs which could
cause embolization of the drug in the patient, or
death
• Institutional pharmacies keep a compatibility chart in
the pharmacy/Some ORs may have them in the room
Summary
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Pharmacokinetics
Pharmacodynamics
Actions/Effects
Abbreviations
Nomenclature
Legal implications
• Metric System
• Conversions/
Mathematics
• Dosage Calculations
• Mixing Medications