Download Route for administration

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Routes of Drug
Administration
Important
Info
The route of administration
(ROA) that is chosen may have
a profound effect upon the
speed and efficiency with
which the drug acts
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• The possible routes of drug
entry into the body may be
divided into two classes:
–Parenteral
–Enteral
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Routes of Administration
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Parenteral Routes
• Intravascular (IV, IA)- placing a drug
directly into the blood stream
• Intramuscular (IM) - drug injected into
skeletal muscle
• Subcutaneous - Absorption of drugs from
the subcutaneous tissues
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I. PARENTERAL
A. Intravenous
B. Intra-arterial
C. Intramuscular
Injection sites for IM
administration
From: Fundamentals of Nursing, 4th edition,
Lippincoitt, Williams & Wilkins
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Intravascular
Absorption phase is bypassed
(100% bioavailability)
1.precise, accurate and almost immediate onset of
action,
2. large quantities can be given, fairly pain free
3. greater risk of adverse effects
a. high concentration attained rapidly
b. risk of embolism (penyumbatan pembuluh
darah)
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Intramuscular
1. very rapid absorption of drugs in aqueous solution
2. Repository (tempat penyimpanan) and slow release
preparations
3. pain at injection sites for certain drugs
Z-track method for IM injections
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Subcutaneous
Sites for SC injection
1. slow and constant absorption
2. absorption is limited by blood
flow, affected if circulatory
problems exist
3. concurrent (bersamaan)
administration of
vasoconstrictor will slow
absorption
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Aradigm Intraject®
NFI device in
protein delivery
Reproduced from: http://www.drugdeliverytech.com/cgibin/articles.cgi?idArticle=178
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Enteral Routes
• Enteral - drug placed directly in the GI
tract:
– sublingual - placed under the tongue
– oral - swallowing (p.o., per os)
– rectum - Absorption through the rectum
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Oral
• Advantages
– Convenient - can be self- administered, pain free,
easy to take
– Absorption - takes place along the whole length of
the GI tract
– Cheap - compared to most other parenteral routes
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Oral
• Disadvantages
– Sometimes inefficient - only part of the drug
may be absorbed
– First-pass effect - drugs absorbed orally are
initially transported to the liver via the portal
vein
– irritation to gastric mucosa - nausea and
vomiting
– destruction of drugs by gastric acid and
digestive juices
– effect too slow for emergencies
– unpleasant taste of some drugs
– unable to use in unconscious (tidak sadar)
patient
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Sublingual/Buccal
Some drugs are taken as smaller tablets which
are held in the mouth or under the tongue.
• Advantages
– rapid absorption
– drug stability
– avoid first-pass effect
• Disadvantages
– inconvenient
– small doses
– unpleasant taste of some drugs
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Isosorbide concentrations after a 5 mg oral or sublingual dose.
Isosorbide Conc (ng/ml)
Data from: Assinder et al. J Pharm Sci 66:775, 1977.
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12
10
8
6
Sublingual
4
2
Oral
0
5
15
30
45
60
90
120
Time (min)
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Rectal
1.
2.
3.
4.
5.
unconscious patients and children
if patient is nauseous or vomiting
easy to terminate exposure
absorption may be variable
good for drugs affecting the bowel (bag paling
bawah) such
as laxatives
6. irritating drugs contraindicated
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RECTAL ROUTE
• Local action
– e.g. rectal route is used primarily for the
treatment constipation
• Systemic action
Advantage
• avoid first-pass effect
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VAGINAL ROUTE
• local action
• systemic action
Marketed preparations include several feminine
hygeine preparations, contraceptives, and
labor inducing drugs.
Advantage
• avoid first-pass effect
Disadvantage
The thickness of the vaginal epithelium and the
blood circulation in this region changes with
menstrual cycle and age, and the drug
absorption also changes accordingly.
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Dosage forms suitable for vaginal route
• tablet
• suppository
• ointment
• gel
• solution
• emulsion foam
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III. PULMONARY
Pharmacologic Agents Administered
via Inhalation
For Systemic Effects For Local Effect
pentamidine
halothane
ergotamine
methoxyflurane
enflurane
isoflurane
nitrous oxide
beclomethasone
terbutaline
cromolyn
metaproterenol
albuterol
pirbuterol
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Inhalation/Pulmonary
1. gaseous and volatile agents and aerosols
2. rapid onset of action due to rapid access to
circulation
a. large surface area
b. thin membranes separates alveoli from
circulation
c. high blood flow
Particles larger than 20 micron and the particles impact in
the mouth and throat. Smaller than 0.5 micron and they
aren't retained.
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Forms of pulmonary delivery
• Metered dose inhaler
• Dry powder inhalers
• Nebulizer
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Metered Dose Inhaler (MDI)
• Metered-dose inhalers
(MDI) provide medication
with compressed gas
– deliver specific measured
dose with each activation
typical MDI
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Techniques for use of MDI devices:
Two finger width
from mouth
Patient must
coordinate
inhalation and
actuation of
device
Use of space or
holding chamber
Placement of
inhaler in mouth
(not for use with
steroids)
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Dry Powder Inhalers (DPI)
• Breath activated
• Micronized drug particles
blended with an excipient
(e.g., glucose or lactose)
• Physical properties of drug
and excipient critical (i.e.,
particle size, shape, surface
morphology, etc)
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Diskus
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Nebulizer
• Device produces small droplets from a
suspension or solution through an air jet
or ultrasonic atomization (quieter, but
more expensive)
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Topical
•Mucosal membranes (eye drops, antiseptic,
sunscreen, callous removal, nasal, etc.)
•Skin
a. Dermal - rubbing in of oil or ointment
(local action)
b. Transdermal - absorption of drug through
skin (systemic action)
i. stable blood levels
ii. no first pass metabolism
iii. drug must be potent or patch
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becomes to large
The skin is generally described in terms of
three tissue layers:
• stratum corneum
• epidermis
• dermis
• subcutaneous fatty tissue
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Dosage forms suitable for
skin/transdermal route.
• cream and ointment
• transdermal patch
e.g. scopolamine trsansdermal patch
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Factors that influence
percutaneous absorption
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Site of application
Condition of skin
Hydration of skin
Temperature
Vehicle
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B. Ocular
•local action
•systemic action
•The cornea of the eye has one of the highest nerve
densities in the human body, as a result patients
perceive pain and discomfort even at low thresholds
of stimulation.
From: Fundamentals of Nursing, 4th edition, Lippincoitt, Williams & Wilkins
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Types of Ophthalmic
Preparations
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Solutions
Suspensions
Ointments
Inserts
Intraocular solutions
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Factors that influence ocular drug
retention
• Technique of application
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Factors that influence ocular drug
retention
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•
Technique of application
Drop size (volume)
Formulation (tonicity, viscosity)
pH of solution
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Route for administration
-Time until effect•
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intravenous 30-60 seconds
intraosseous 30-60 seconds
endotracheal 2-3 minutes
inhalation 2-3 minutes
sublingual 3-5 minutes
intramuscular 10-20 minutes
subcutaneous 15-30 minutes
rectal 5-30 minutes
ingestion 30-90 minutes
transdermal (topical) variable
(minutes to hours)
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