Download Pharmacologic Principles

Pharmacologic Principles
Jan Bazner-Chandler RN, MSN, CNS,
CPNP
Chapter 2
Pharmacology
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The study or science of drugs
Knowledge of pharmacology allows nurse to
understand how drugs affects humans.
Naming the drugs
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Chemical name
Generic name
Trade name
Chemical name
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Chemical composition and molecular
structure
Generic Name
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Shorter and simpler than the chemical name
Trade Name
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Drugs registered trade mark
Generic and Trade Name
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Generic name: acetaminophen
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Less expensive – chemically similar to trade name
drugs
Trade name: Tylenol, Tempra, Datril
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More expensive
Pharmaceutics
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How dosage forms influence the way in which
the body metabolizes a drug and the way the
drug affects the body.
Dosage Forms
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A variety of dosage forms exist to provide
both accurate and convenient drug delivery
systems.
These delivery systems are designed to
achieve a desired therapeutic response with
minimal adverse effects.
Dosage Forms
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Enteral: taken by mouth or PO
Parenteral: intramuscular or intravenous
Topical: applied to the skin, a patch,
suppositories (rectal or vaginal)
Dosage Form
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Parenteral
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Injections
Solutions
Suspensions
Emulsions
Powders for reconstruction
Sublingual or buccal
Chewable Tablets
Chewable Tablets
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Can be chewed
Used for children
Used in the client that has a hard time
swallowing pills
Break down of the drug starts in the mouth
Tablet
Tablets
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Are made to be swallowed whole
Are often scored so a half-dose can be give
Capsules
Capsules
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To be swallowed whole
Often are sustained release – 12 or 24
dosing
Enteric Coated Tablets
Enteric coated
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Tablets are coated so that they do not break
down in the stomach
Absorption of the drug takes place in the
small intestine.
Cannot be divided into smaller doses
Sublingual
Sublingual
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The tablet is put under the tongue
Medication is absorbed through the buccal
mucosa.
Used in drug like nitroglycerine used to
reduce chest pain.
IM and SC
Intramuscular or subcutaneous
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IM or the “shot” – injected into the deep muscle of
buttocks, thigh or upper arm
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Antibiotics
Pain medications
Subcutaneous – injected into the fat layer just
below the skin
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Insulin
Anticoagulation meds: Heparin of Lovenox
Intravenous or IV
Intravenous or IV
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Medication is administered right into the vein.
Medications is readily absorbed right into the
circulation.
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Antibiotics
Regular insulin only
Pain medications
Anti-nausea or anti-emetics
Chemotherapy
Local Administration
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Adhesive patches
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pain control
nitroglycerine patches
Hormones
birth control patches
nicotine patches
Topical Applications
o
o
o
Sunscreen
Antibiotic ointments
Cortisone
Eye, Ear and Nose Drops
Drops written as gtts
Eye Drops or Eye Ointment
Ear Drops
Vaginal or Rectal (PR)
Rectal Suppositories
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Excellent route of administration of
medications for the client that is:
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Vomiting / nausea
Refuses to take medication PO
Difficulty swallowing a medication
Infants – fever or pain medications
acetaminophen (Tylenol) Suppository
Pharmacodynamics
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The mechanism by which specific drugs
produce biochemical and physiologic
changes in the body.
Pharmacokinetics
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Movement of drugs across body membranes
to reach the target organ.
4 ways drugs move throughout the body:
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Absorption
Distribution
Metabolism
Excretion
Absorption
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Process that occurs from the time the drug
enters the body to the time it enters the
bloodstream to be circulated.
Onset of drug action is largely determined by
the rate of absorption.
Absorption
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Think of how the drug gets into the circulatory
system and the dosage needed to bring the
blood levels up to therapeutic levels.
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Dosage
Interval of administration
Route of administration
Oral Drugs or PO Drugs
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Dosage is determined by how much of the
drug is required to be taken by mouth to
given the desired affect.
Bioavailability – portion of the drug that
reaches the systemic circulation.
First-pass
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If a drug is metabolized by the liver before it
reaches the systemic circulation, some of the
active drug will be inactivated or diverted
before it can reach the general circulation.
Most drugs administered by mouth have less
than 100% bioavailability.
Drugs administered by the intravenous route
have 100% bioavailability.
Critical thinking question
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What are the effects on bioavailability in:
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The infant that has an immature liver.
The geriatric patient with a poor functioning liver
The client with liver disease.
Where does absorption happen?
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Very few drugs actually absorbed in the
stomach (alcohol)
Small intestine
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large surface area for absorption of nutrients and
minerals
most drugs absorbed in small intestine
Degree and Rate of Absorption
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Depends on
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Route
Age and physical condition of client
Lipid or water solubility of drug
Potential drug interactions with other drugs
What else might influence oral drug
absorption?
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Food in stomach
Certain juices – grapefruit juice
Milk – binds with molecules of some drugs so
that the drug is never absorbed
Orange juice – enhances absorption of iron
taken orally
The coating on the tablet: chewable, enteric
coated, slow release capsules
Distribution
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Transportation of drug molecules within the
body after the drug is absorbed into the blood
stream.
Distribution
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Drug needs to be carried to the site of the
action.
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Carried by the blood and tissue fluids to the sites
of pharmacological action.
Distribution depends on adequacy of blood
circulation.
Key Concepts of Distribution
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Protein binding – drug molecules need to get
from the blood plasma into the cell.
Protein binding allows part of the drug to be
stored and released as needed.
Some of the drug is stored in muscle, fat and
other body tissues and is gradually released
into the plasma.
Just how does the drug get into the cell?
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Drug must pass though the capillary wall
Blood brain barrier – very effective in keeping
drugs from getting into the central nervous
system or CNS – limits movement of drug
molecules into brain tissue
Metabolism
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Method by which the drugs are inactivated or
biotransformed by the body.
Most drugs metabolized in the liver by
cytochrome P450 (CYP) enzyme.
Hepatic drug metabolism or is major
mechanism for terminating drug action and
eliminating drugs from the body.
What can stop this process?
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Enzyme inhibition
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Other drugs
Combination drugs
Liver disease
Impaired blood circulation in person with heart
disease
Infant with immature livers
Malnourished people or those on low-protein diets
An important concept!
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First-pass effect – some drugs are
extensively metabolized or broken down in
the liver and only a part of the drug is
released into the systemic circulation
This is why dosage is important – how much
drug needs to be taken in to give the desired
effect and how often does it need to be taken
Excretion
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Refers to the elimination of the drug from the
body.
Requires adequate functioning of the
circulatory system and organs of excretion.
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Kidneys via urine – most drugs excreted in the
urine
Liver via bile and into the feces
Lungs via exhaled air
Saliva, tears and sweat or skin
Important concepts
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Absorption – small intestine, skin, rectal or
vaginal tissue
Metabolism – liver
Distribution – circulation (blood or plasm)
Excretion – urine, stool, skin
Dosing Schedules
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Determined by drug’s pharmacokinetic
properties
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Route of administration
Onset of action
Peak concentration level
Duration of action
Half-life
Onset, Peak, Elimination
Onset of action
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The time when the drug’s effects first become
noticeable.
Peak Concentration
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Maximum blood concentration level achieved
through absorption; at this level most of the
drug reaches the site of action and provides
therapeutic response.
Duration
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Duration of action: the length of time a drug
acts on the body.
Half-life
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The time required for a drug’s plasma
concentration to decrease to 50%.
Pharmacodynamics
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Study of what the drug does to the body.
Pharmacotherapeutics
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Therapeutic effect: the clinical indication for
administering the drug.
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Prevent disease
Treat disease
Preventive
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Immunizations
Treat Disease
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Acute therapy
Maintenance therapy
Supplemental therapy
Palliative therapy
Supportive therapy
Prophylactic therapy
Acute Therapy
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Intensive drug therapy implemented in
acutely ill clients
Often used to sustain life or treat disease
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ICU
Emergency Treatment
Cardiac Resuscitation
Septic shock – IV antibiotics
Maintenance Therapy
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Prevent progression of the disease
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Insulin for diabetes
Anti-hypertensive drugs to control hypertension or
high blood pressure
Control chronic illness
Cholesterol control
Palliative Therapy
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Make client as comfortable as possible
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Pain control in cancer clients
Oxygen for client with pulmonary disease
Supportive Therapy
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Maintains integrity of body functions while
client is recovering from illness or trauma
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Intravenous fluids to prevent dehydration
Blood for anemia or blood loss
Prophylactic Therapy
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Given to prevent illness or infection
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Antibiotics prior to dental surgery
Antibiotics prior to orthopedic procedure
Most important job of the nurse!
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Monitoring the patient for effectiveness of
therapy.
Response to medication needs to be
evaluated.
Did the medication work!
Monitor for adverse effects
Adverse Drug Reaction
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Adverse drug reaction ADR: refers to
unwanted or potential harmful effects of a
drug; all drugs have one or more adverse
reactions in addition to having the desired
effect.
Classification of Adverse Reactions
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Drug related reactions
Sensitivity-related reactions
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Hypersensitivity
Anaphylaxis
Toxicity
Unexpected or peculiar response to a drug
Interactions
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Drugs can interact with other drugs or food.
Drugs can interact with other drugs
In the drug history always ask about OTC
and herbal therapy that may interact with
prescribed medications.
Nursing Responsabilities
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Always check to seen when medication
should be taken
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With food
On an empty stomach
Before meals
After meals
Specific foods that may need to be avoided