NURS - 343 PHARMACOLOGY EXAM 1

PHARMACOKINETICS AND ROUTES OF ADMINISTRATION
I. Drug
A. Any chemical that affects the physiologic processes of a living organism
II. Pharmacology
A. Study or science of drugs
III. Drug Names
A. Chemical name: name of the med that reflects its chemical composition and molecular
structure.
B. Generic name: official or nonproprietary name the USANC gives a medication.
1. Ex. Ibuprofen
C. Trade name: brand or proprietary name the company that manufactures the
medication gives it.
1. Ex. Advil and Motrin
I. Pharmaceutics: The study of how various drug forms influence the way in which the drug
affects the body
II. Pharmacokinetics: How the meds travel through the body
III. Phases of Pharmacokinetics
A. Absorption: transmission of meds from the location of administration to the
bloodstream. The most common routes are enteral and parenteral. Rate determines
how soon the meds will take effect. Amount determines the intensity of meds. Route
affects the rate and amount of absorption.
1. Oral →
BARRIERS: Meds must pass through the layer of epithelial cells that line the GI
tract.
2. Sublingual or buccal →
BARRIERS: swallowing before the meds are completely dissolved can cause the
gastric pH to inactivate the medication
3. Other mucous membranes (rectal, vaginal) →
BARRIERS: presence of stool in the rectum or infectious material in the vagina
limits tissue contact. Or the sphincters are not working properly and the
patient is not able to hold in the medication.
4. Inhalation (mouth or nose) →
BARRIERS: Inspiratory effort. Some patients have COPD and they are unable to
get a deep enough breath. Sometimes patients do not use the inhaler the
correct way.
5. Intradermal or topical →
BARRIERS: Close proximity of epidermal cells; lipid soluble meds can be slower
processed bc it’s fat that is being absorbed.
6. Subcutaneous or intramuscular →
BARRIERS: Capillary walls have large spaces between cells.
7. Intravenous →
BARRIERS: No barriers
B. Distribution: transportation of medications to sites of action by bodily fluids.
1. Circulation: poor blood flow can restrict med distribution such as those with
peripheral vascular or cardiac disease
2. Permeability of the cell membrane: meds must be able to pass through tissues
and membranes to reach its target area
3. Plasma protein binding: meds compete for protein binding sites within the
bloodstream specifically albumin. This determines how much of the meds will
leave and travel to the target tissues.
C. Metabolism: changes meds into less active or inactive forms by the action of enzymes.
Occurs in the liver but also the kidneys, lungs, intestines and blood.
Factors influencing the rate of medication metabolism →
1. Age: Hepatic medication metabolism declines with age. Older adults usually
get smaller doses of meds because it can stay in their body for a longer period
of time.
2. Increase in some med-metabolizing enzymes
3. First-pass effect: liver inactivates some meds on their first pass through and
can require for the meds to be distribute in a nonenteral route such as IV
4. Similar metabolic pathways:
5. Nutritional Status
D. Excretion: elimination of the meds from the body primarily through the kidneys. Also
takes place through the liver, lungs, intestines and exocrine glands (breast milk).
Kidney dysfunction can lead to an increase in the duration and intensity of a
medication’s response so it is important to monitor BUN and creatinine levels.
IV. Medication Responses: Maintains it at a minimum effective concentration
A. Therapeutic Index: Meds with a high therapeutic index (TI) have a wise safety
medication therefore it doesn’t need for routine serum medication-level monitoring.
However, those meds with a low TI require close monitoring. Nurses should consider
the route of administration when monitoring for peak levels. For trough level, obtain a
blood sample.
B. Half Life: the time for the meds in the body to drop to 50%
1. Short half life → med leaves the body quickly (4-8hrs), short intervals
2. Long half life → med leaved the body more slowly, over 24 hrs. Risk of med
accumulation and toxicity. Long intervals w/o loss of therapeutic effects, longer
time to reach a steady state.
C. Pharmacodynamics: interactions between meds and target cells, body systems, and
organs to produce effects.
1. Agonist → binds to receptor. (ex. Morphine binds to a receptor that activates it
to produce analgesia, sedation and constipation.
2. Antagonists → blocks the usual receptor activity. (ex. Losartan which is an
angiotensin II blocker, it blocks the angiotensin II receptor on blood vessels
which prevents vasoconstriction.
3. Partial agonists → acts as both. (ex. Nalbuphine acts as antagonists at mu
receptors and an agonist at kappa receptors causing analgesia with minimal
respiratory depression at low doses.
V. Routes of Administration
A. Oral or Enteral: tablets, capsules, liquids, suspensions, elixirs, lozenges (most common
route)
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B. Sublingual and Buccal: under the tongue or between the cheek and gum, directly
enters the bloodstream and bypass the liver.
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C. Liquids, Suspensions, and Elixirs:
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D. Transdermal: med in a skin patch for absorption through the skin, producing systemic
effects
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E. Topical: painless and limited adverse effects
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F. Instillation (drops, ointments, sprays): used for eyes, ears, and nose
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G. Inhalation: administered through metered dose inhalers (MDI) or dry powder inhalers
(DPI)
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H. Nasogastric and Gastrostomy tubes
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I. Suppositories
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J. Parenteral
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K. Intradermal
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L. Subcutaneous and Intramuscular
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M. Z-track
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N. Intravenous
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O. Epidural
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