ROUTES OF DRUG ADMINISTRATION
Drugs are administered according to the
preparation of the drug and effect desired, physical and mental condition of
client. The route of administration should be indicated when prescribe the
medicine. The nurse should ensure that the pharmaceutical preparation is appropriate
for the specified route.
The
route of administration that is chosen may have a profound effect upon the
speed and efficiency with which the drug acts
The Route of administration is
determined by the physical characteristics of the drug, the speed which the
drug is absorbed and/ or released, as well as the need to bypass hepatic
metabolism and achieve high concentration at particular sites.
Systemic Routes
Enteral through GIT
·
Orally
·
Buccal or sublingual
·
Rectal
Parental: Par-way, enterm-intestine
·
Intravenous (IV)
·
Intramuscular (1M)
·
Subcutaneous (SC)
Inhalation
Topical
Enteral Routes
Enteral
- drug placed directly in the GI tract:
·
sublingual - placed under the tongue
·
Buccal:
placed against the mucus membranes of the cheek.
·
Oral
-
swallowing
1. Oral administration:
Oral
administration is the most common, least expensive, easiest and safe method of
drug administration and convenient for most patients.
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
·
Can also be administered through feeding
tubes
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
·
Unpleasant taste of drugs
·
Some drugs cause staining of teeth(ferrous
sulphate, iron)
·
Effect too slow for emergencies
·
Unpleasant taste of some drugs
·
Unable to use in unconscious patient
·
Inappropriate when GI Tract has reduced
mobility
·
Cannot be used before certain diagnostic
tests or surgical procedures
·
Can be aspirated by seriously ill clients.
First-pass Effect:
The
first-pass effect is the term used for the hepatic metabolism of a
pharmacological agent when it is absorbed from the gut and delivered to the
liver via the portal circulation. The greater the first-pass effect, the less
the agent will reach the systemic circulation when the agent is administered
orally.
2. Sublingual:
Drug is placed under the tongue, where it
dissolves. In a relatively short time the drug is absorbed to blood stream
under the tongue. (E.g. Nitro glycerides).
3. Buccal:
In
buccal administration, the medication is held in mouth against the mucous
membrane of cheek until it dissolves. The drug may act locally or systemically
when it is swallowed in saliva. Alternate cheeks with subsequent dose.
Instruct - not to chew, swallow or take
liquids.
Advantages
·
Rapid absorption
·
Drug stability
·
Avoid first-pass effect
Disadvantages
·
Small doses
·
If swallowed may be inactivated by gastric
juice
·
Unpleasant taste of some drugs
4. Insertion:
In
this method, the drug is introduced in to the body orifice. E.g . Suppositories
Rectal
Medication
in suppository form (small cylindrical, waxy base) may be placed in the rectum
to treat systemic complaints or as a laxative to encourage bowel movements.
Liquid
medications may be instilled in to the rectum using an enema to encourage bowel
movements or to treat clients with elevated potassium levels.
·
Can be used in unconscious patients and
children and if patient is having nausea or vomiting
·
Easy to terminate exposure
·
Absorption may be variable
·
Good for drugs affecting the bowel such as laxatives
·
Irritating drugs contraindicated
·
Can be used when drug has objectionable
taste or odor
·
Drug released at slow, steady rate
Disadvantage:
·
May be perceived as unpleasant by the
client
·
Provides a local therapeutic effect
Administration of drug in form of powder,
vapour, in to a wound or body cavity by blowing
with an insufflators.
6. Implantation:
Implantation
means planting or putting in of solid drugs in to the body tissues.
7. Topical application:
Topical
applications are those applied to circumscribed surface area of the body.
·
Dermatologic preparations.
·
Instillation (fluid into a body
cavity)-fluid is retained
·
Irrigation (pouring a drug in liquid form
in to a body cavity)-fluid is not retained
·
Inhalations.
·
Spraying medication into body cavity
Topical applications include
1.
Dermatologic preparations: applied to
the skin
a. Dermal - rubbing
in of lotions, creams, oil or ointment to the skin
·
Used to treat a skin or wound infection or
skin disease or decrease symptoms of skin disorders
·
Local effect
·
Painless
b. Transdermal - medications
designed to be absorbed through the skin for systemic effects are called
Transdermal medications. Usually prepared as patches. Allows controlled amount
of medication to be supplied over 24-72 hrs.
Disadvantage:
·
leaves oily substance on skin
·
Soils clothes
2.
Ophthalmic medications: Ophthalmic medications
or ointments are administered to treat conditions of the eyes. Medications are
instilled in to the lower conjunctival sac.
3.
Otic medications: Medications may be instilled in to
the ear to treat external ear infections or to soften and remove ear wax.
4.
Nasal Medications: Solutions are usually sprayed or instilled
in to the nose. Usually used to treat nasal congestion.
5. Vaginal
medications: medications given vaginally comes in various forms: Jelly’s,
liquids (douches) creams, tables or suppositories. Provide a local effect.
Disadvantages: May be
messy and may soil clothes
Inhalation
May
be used to induce anaesthesia or to treat respiratory conditions.
Inhaled
medication may be administered through a hand held nebulizer, a metered or a
mechanical ventilator
Liquid
medications are added to a receptacle in the ventilator or nebulizer and
changed in to a gas form when air or 02 flows over them.
Rapid
onset of action due to rapid access to circulation
Drug
can be administered to unconscious client
Intraocular route
·
Inserting a medication similar to contact
lens into the patient's eye.
·
The eve medication disk has 2 soft outer
layers that have medication enclosed in them.
·
Nurse inserts disk into eye —remains there
up to I week
8. Parentral administration
Parentral
means administration of therapeutic agents outside the alimentary tract.
(Parsbeside, enteron- intestine).
·
Intra
muscular (IM) - drug injected into skeletal muscle
·
Intra
venous (IV) - placing a drug directly into the blood
stream
·
Intradermal,
under the epidermis, to the dermis.
·
Intra-arterial
-
into artery
·
Intra
cardiac - in to the cardiac muscle
·
Intra
thecal or intra spinal - in to the spinal cavity
·
Intraosseous
-
in to the bone marrow
·
Intraperitonial
(peritoneal cavity) - in to the peritoneal cavity.
·
Subcutaneous
-
Absorption of drugs from the subcutaneous tissues
·
Inhalation
-
Absorption through the lungs
·
Epidural
-
in to the epidural space
·
Intrapleural
- in
to the pleural space
·
Intraarticular
- into
a joint
Intravenous:
·
Absorption phase is bypassed (100%
bioavailability)
·
precise, accurate and almost immediate
onset of action,
·
Large quantities can be given.
Disadvantage:
·
Greater risk of adverse effects
·
Limited to highly soluble drugs
·
Drug distribution is inhibited by poor
circulation.
·
Risk of introducing infections
Intramuscular:
·
rapid absorption of drugs
·
can administer larger volumes than
subcutaneous
Disadvantage:
·
Pain at injection sites for certain drug
·
Can produce anxiety
SUBCUTANEOUS (HYPODERMIC): the
subcutaneous tissue, just below the skin
·
Slow and constant absorption
·
Absorption is limited by blood flow,
·
Affected if circulatory problems exist
Disadvantages
·
More expensive than oral
·
Slower than intramuscular administration
·
Breaks skin barrier
·
Can administer only small volume
·
Some drugs can irritate tissues and cause
pain can produce anxiety
INTRADERMAL
Intradermal
(ID) under the epidermis (into the dermis)
·
Drug inj. into layers of skin
·
Multiple puncture of epidermis
·
BCG, Small pox vaccination
·
Testing drug sensitivity
Small
dose only can be given
Route for administration -Time until effect-
·
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)
COMMENTS