PHARMACOLOGY

1. Pharmacological
principles
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2. Learning Objectives
At the end of this class, the student will be able to:
1.Define the terms pharmacology, pharmaceutics, pharmacokinetics,
pharmacodynamics and Pharmacotherapeutics, pharmacognosy and
toxicity.
2.Explain the four phases of pharmacokinetics.
3.Identify factors that can affect the absorption and distribution of drugs
4.Discuss the types of drug reactions and interactions that may occur.
5.Research drug information in their drug handbook.
6.Discuss the pharmacokinetics in relation to lifespan considerations.
7.Describe pregnancy safety categories.
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3. Pharmacology
•The study of drugs
• Drugs: any chemical that affects the
physiological processes of a living organism
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4. Drug Names
Chemical name
• drug’s chemical composition and molecular structure
generic name
• Name given to the drug and approved by Health Canada under
the Food and Drugs Act and Food and Drug Regulations
Trade name
• Name given to a drug/Registered trade mark ®
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5. Pharmacological Principles
•Pharmaceutics
• Science of preparing and dispensing drugs
•Pharmacokinetics
• What the body does to drugs
•Pharmacodynamics
• Study of what drugs do to the body
•Pharmacotherapeutics
• Study of how drugs are used to treat disease
•Toxicity
• Study of poisons and unwanted responses to drugs and other
chemicals
•Pharmacognosy
• Study of characteristics of natural drugs and their sources
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6. Pharmaceutics: Amoxicillin
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7. Pharmacokinetics
The study of what the body does to a drug:
Absorption
Distribution
Metabolism
Excretion
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8. Absorption
• The movement of a drug from its site of
administration to the bloodstream for distribution to
the tissues
• Most drugs are absorbed in the small intestine
• Passive diffusion
• Active transport
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9. Routes of Administration
Enteral (GI tract)
◦ Oral, sublingual, buccal
Parenteral
◦ Intravenous, intramuscular, subcutaneous, intradermal,
intrathecal, intraarticular, intraarterial
Topical
◦ Skin, ears, eyes, nose, inhalation, rectum,
vagina
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11. Factors That Affect
Absorption
•Dosage formulation
•Route of administration
•Status of the absorptive surface
•Food or fluids administered with the drug
•Rate of blood flow to the small intestine
•Status of GI motility
•Other medications
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12. Factors That Affect Absorption:
First-Pass Effect
• A drug given orally undergoes a first-
pass effect
• First-pass effect is the metabolism of
a drug by the liver before its systemic
availability
• An orally administered drug passes
through the stomach, intestine,
intestinal wall, to the portal blood
system and the liver before it enters
the systemic circulation (<100 %
bioavailability)
• The same drug—given IV—
bypasses the liver, preventing the
first-pass effect and more drug is
available (100% bioavailability)
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13. 13
Figure 2-3 First-pass effect is the metabolism of a drug by
the liver before its systemic availability.
Box 2-1 Drug Routes and First-Pass
Effects

14. Distribution
• The movement of drug from the systemic
circulation to and from the tissues
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15. Factors that affect
distribution
• Tissue perfusion
• Temperature
• Size of drug molecule
• Water soluble versus fat soluble drugs
• Blood brain barrier
• Protein binding
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16. Distribution: Protein binding
• Many drugs bind to proteins in plasma
• Albumin major carrier of drugs
• Drug molecule needs to bind with a protein that will transport it
from one side of the cell membrane to another
• Drug molecules bound to protein are inactive
• Protein binding allows for drugs to be stored and released as
needed
• Only unbound drugs are active and can reach its target
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17. Metabolism
• The biochemical transformation of a drug into an
inactive metabolite, a more soluble compound, or a
more potent metabolite = biotransformation
• Main organ - liver
• Prodrugs - require metabolism to make them active
• Cytochrome P450 - family of enzymes that are
responsible for most drug metabolism reactions
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18. Excretion
• Process where the drug leaves the body
• Main route – kidneys through urine
• Other ways
• Air that we exhale
• Sweat
• Feces
• Breast milk
• Other body secretions
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19. Question?
A 74 year old man with liver disease is admitted to the medical
unit with abdominal pain. He has a history of hypertension. Due to
the unexplained abdominal pain, he has an order to remain NPO.
An intravenous infusion is ordered and the nurses have a difficult
time inserting the intravenous line.
What factors from this client’s history will affect:
a) Absorption
b) Distribution
c) Metabolism
d) Excretion
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20. Half life and Steady state
•Half life (T½)
• Time required for the body to
eliminate 50% of the drug
• Clinically useful for determining
when a client is at a steady state
◦ A drug with a short half-life requires
more frequent administration
◦ A drug with a long half-life requires less
frequent administration
•Steady state
• Concentration of a drug in
the systemic circulation that
will eventually be achieved
when a drug is administered
at a constant rate
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21. A client is given 100 mg of a drug
that has a half-life of 12 hours...
Time (hours) Half-life T½ Drug Remaining in
Body (%)
0 100 mg
12 1 50 mg
24 2 25 mg
36 3 12.5 mg
48 4 6.25 mg
60 5 3.12 mg
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22. A client takes 200 mg of a drug that has a half
life of 12 hours. How much of the drug remains
in the body 36 hours after administration?
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Time (hours) Half-life T½ Drug Remaining in
Body
0 200 mg
12 1
2
3
4
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23. Onset, Peak, Duration
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24. Drug Handbook time...
Order: ibuprofen 400 mg PO q6h for pain
• Onset
• Peak
• Duration
• Half life
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25. Therapeutic Drug
Monitoring
Peak Level
• Highest blood level of the drug
Trough Level
• Lowest blood level of the drug
Therapeutic Index
• The ratio between a drug’s therapeutic benefits
and its toxic effects
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26. Pharmacodynamics
•What the drug does to the body
•“Mechanism of Action”/Action
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27. Pharmacodynamics
(cont’d)
• Most drugs have an affinity for certain tissues/receptors to
exert an effect
• Basic drug actions:
• Agonists: bond and elicit a full response (e.g. Morphine)
• Partial agonists: bond and elicit a partial response (e.g.
Buprenorphine is a partial agonist meaning, it activates the opioid
receptors in the brain, but to a much lesser degree than a full agonist.
• Antagonists: bond and prevent other drugs from occupying the site (e.g.
naloxone)
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28. Monitoring:
Contraindications
◦ Any special symptom or circumstance that indicates
that the use of a particular drug or procedure is
dangerous, not advised, or has not been proven safe
for administration
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29. Drug Handbook time...
Order: heparin 4000 units subcut at bedtime
• Contradictions
• Mechanism of Action/Pharmacodynamics
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30. Pharmacotherapeutics
•What we want the drug to achieve
•“What therapeutic effects are we looking
for?”
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31. 31
Pharmacotherapeutics:
Kinds of Therapy
 Acute – improve life
threatening or serious
condition
 Empiric – based on
experience not science
 Maintenance – maintain a
condition/prevent further
progression
 Palliative – reduce the
severity of a condition or
pain
 Prophylactic – prevent a
disease or condition
 Replacement – provide
chemicals missing by
the client
 Supportive – for
condition other than
primary disease
 Supplemental – avoid
deficiency

32. Drug Interactions
The alteration of action of a drug by:
• Other prescribed drugs
• Over-the-counter medications
• Natural health therapies
• Foods
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33. Pharmacodynamic Interactions:
Drug Interactions (cont’d)
•Additive effect:
• Tylenol and Ibuprofen
•Synergistic effect
• Alcohol and Acetaminophen
•Antagonistic effect
• Caffeine and Alcohol
•Incompatibility:
• https://www.bbraunforsafety.com/en/drug-
incompatibility.html#health-consequences
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34. Adverse effects
◦ Predictable, well-known reactions that result in little
or no change in patient management
◦ Not usually severe enough to warrant discontinuing
the medication
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35. Adverse Drug Events(ADE)
ADE = adverse drug reaction or medication error
Adverse drug reactions:
◦ A reaction to a drug that is unexpected and undesirable and
occurs at therapeutic ranges
◦ Mild reactions TO severe reactions
◦ Idiosyncratic reaction
◦ Sensitivity to aspirin causing an attack of asthma
◦ Teratogenic
◦ https://www.medicinenet.com/script/main/art.asp?articlekey=9334
◦ Carcinogenic
◦ Mutagenic
◦ Immunosuppressives
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36. Pharmacognosy
•The study of natural drug sources
•Main sources for drugs
• Plants
• Animals
• Minerals
• From microorganisms (bacteria or fungi)
• Genetic engineering
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37. Toxicity
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38. Drug Handbook time...
Order: Lasix 40 mg po q8h
• Contraindications
• Onset
• Peak
• Duration
• Side effects
• Therapeutic effects
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39. Generic Name-acetaminophen
Trade Name-Tylenol
Classification-nonopioid analgesic, antipyretic
Action: Blocks pain impulses, relieves pain. Reduces fever. No anti-inflammatory properties.
Uses: Mild to moderate pain or fever.
Dosage and Routes: Adult and child >12yrs: 325-650mg q4-6hr prn max 4g/day
Side Effects: stimulation, drowsiness, nausea, vomiting, abdominal pain
OD: hepatotoxicity, hepatic seizure. Renal failure
Contraindications: alcohol- contains yellow dye #5, alcohol, sugar, saccharine
Precautions: Pregnancy (B), breast feeding, geriatric pt's, anemia, renal/hepatic disease, chronic alcoholism.
Pharmacokinetics: 85-90% metabolized by the liver, excreted by the kidneys. Maybe toxic if OD. Crosses the placenta in low
concentrations. excreted in breast milk. half life:1-4 hrs
Onset slow, peak 1-2 hrs, duration 4-6hrs.
Interactions: warfarin , alcohol
Renal adverse effects: NSAIDS, ASA
Nursing Considerations/Teaching: assess hepatic and renal function.
Note fever and pain: type of pain, location, intensity and duration.
Allergic Reactions: rash, urticaria
Teach not to exceed recommended dose, acute poisoning with liver damage may result. Not to use with alcohol or herbals.
Chronic OD: bleeding, bruising, malaise, fever and sore throat.
Acute Toxicity: nausea, vomiting, abdominal pain.
Notify prescriber if pain or fever persists over 3 days.
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Drug Profile Card

40. Homework…
•Prepare a drug card for
• Levothyroxine 200 mcg po daily
• Use the drug card template posted on BB
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41. Considerations for
Special Populations
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42. Pregnancy Considerations
• Use of drugs during pregnancy should be avoided or minimized
when possible
• If possible, drug therapy should be delayed until after the first
trimester, especially when there is danger of drug-induced
developmental defects
• Potential fetal risks must be compared to maternal benefits when
drug therapy is required
• Drug studies in pregnant women are rare, so the teratogenicity
of many drugs is unknown

44. Breastfeeding/Lactation
•Breastfed infants are at risk for exposure to drugs consumed by
the mother
• Many drugs cross from the mother’s circulation into breast milk
and subsequently to the infant, although in small amounts
because this is not the primary excretion route
•Consider harm-to-benefit ratio when deciding whether a
breastfeeding mother should take a particular drug

45. Drug Handbook time
For the following drugs,
• amoxicillin
• phenytoin
•Identify the pregnancy category.
•What does the category mean?

46. Factors Affecting
Pharmacokinetics for Children
Absorption
•Stomach lacks acid to kill bacteria & gastric emptying slowed
•Skin is thin and permeable
Distribution
•Protein binding is decreased
•Blood brain barrier is immature
Metabolism
•Liver is immature, impairing drug metabolism
Excretion
•Kidneys are immature, impairing drug excretion

47. The Older Adult/Seniors
A person over the age of 65
• Increased incidence of chronic illnesses
• Polypharmacy/multidrug regimen
• Increased risk of adverse drug reactions

48. The Older Adult/Seniors:
Pharmacokinetics
Absorption
• Gastric pH less acidic
• Slowed gastric emptying
• Reduced absorptive surface area due to flattened intestinal villi
Distribution
• Increased fat content
• Decreased production of proteins by the liver, resulting in decreased protein
binding of drugs (and increased circulation of unbound/active drugs)
Metabolism
• Aging liver produces fewer microsomal enzymes
• Blood flow to the liver is reduced
Excretion
• Decreased glomerular filtration rate
• Decreased number of intact nephrons