Transcript Other Parenteral Administration Routes

Principles and Methods of
Drug Administration
CHAPTER 3 -3
Dr. Dipa Brahmbhatt VMD MpH
[email protected]
Parenteral vs. Non-Parenteral
Administration Routes
Parenteral Administration
• Literally means
“administered in the space
between the enteric canal
(the GI tract) and the surface
of the body”
Non-Parenteral Routes
• Drugs given by mouth =
Oral administration (PO)
• Rectally
• Sublingual
Other Parenteral
Administration Routes
• Inhalation administration introduces drug to the
animal by having it breathe the drug into the lungs
– Particles diffuse across the alveolar membrane
• Topical medication goes on the surface of skin or
mucous membrane
– Forms of topical medication are summarized in Table 3-2
in your textbook
• Other parenteral administration routes are listed in
Table 3-1 in your textbook
Route of Administration
• Injectable / Parenteral
• Local Routes
– ‘Applied or given directly where the action of the
drug is desired’
– Inhalation, topical (skin, eye, ear), other routes
(rectal, vaginal, transdermal patches)
• Oral Route
Inhalation
• Drugs are administered in
the form of a gas/spray
and are rapidly absorbed
into the bloodstream.
• An animal breathes in the
drug > the lungs > alveoli
where the particles
diffuse into the
bloodstream > distributed
throughout the body
Inhalation
• Gas Anesthesia (most common)
– Drugs are volatilized (turned into gases)
from liquids using a vaporizer
• Treat respiratory conditions
– Bronchodilators (anticholinergics),
mucolytic enzymes, antibiotics, steroids
– Drugs are nebulized (turned into a fine spray)
Topical
• Dermatology (ear: drops, ointments and cream) and
and ophthalmology (liquid drops and ophthalmic
ointment)
• Applied to the skin surface or mucous membranes
• Forms: gel, ointment, cream, paste, liniment, lotion,
powder, aerosol, or liquid drops
• First dissolved and then diffused into the skin
• Slowest route of absorption in the body as a whole
• High concentration of drug locally,
may be absorbed systemically
Topical
•
•
•
•
Localized skin infections/ allergies, abrasions
May be irritating, animal may chew/lick it off
Easy to administer
Can use drugs that otherwise
would be toxic if injected
• Have to shave fur for good
contact
• Other topical routes: nasal, rectal, vaginal
Topical
• Solution: Clear liquid preparation, 1/more solutes and
1/more solvents
– Solvent: the dissolving substance of a solution
– Solute: the dissolved substance of a solution
• Emulsion: A mixture of 2 immiscible liquids, one
dispersed throughout the other in small droplets
– Water – oil emulsion
• Suspension: A finely divided, undissolved substance
dispersed in water/oil. Liquid preparation that contains
solid drug particles suspended in a suitable medium
FORMS OF TOPICALS
Drug suspended in….
•
•
•
•
•
•
•
•
Aerosols – solvent packaged under pressure
CREAM – water-oil emulsion
GEL – semisolid or jelly-like substance
Liniments – oily, soapy, or alcohol-based substance. Applied
with friction
Lotions – liquid for dabbing, brushing, or dripping on skin
without friction
OINTMENT – semisolid, lipid - based preparation that melts
at body temp
PASTE – semisolid that retains its state at body temp
Powder – powder for external lubrication or absorption
Rectal Drug Administration
• Alternative for delivering drugs: dangers
presented to the vet staff / inability to
administer the drug because of the animal’s
condition
• Usually much slower than oral
drug absorption
• Local irritation is a side effect
of rectal drug therapy
• Suppositories: melt/dissolve when inserted in
body orifice
Vaginal Drug Administration
• Therapeutic macromolecules
• The rate and extent of absorption depends on
–
–
–
–
Drug formulation factors
Vaginal physiology
Age of the patient
Phase of the estrous cycle of the patient
• Vaginal drug delivery systems include
– Controlled internal drug release devices
– Progesterone-releasing intravaginal devices
– Vaginal sponges
Transdermal Drug
Administration
• Delivered through a patch on the skin
• It passes from skin to
bloodstream :drug to be
delivered slowly and
continuously (hrs/ days/ longer)
• Skin irritation is one side effect
• Only drugs needed in relatively small daily
doses can be given through patches
Inhalation
Topical
Rectal
Vaginal
Transdermal
Field
•Anesthesia
•Dermatology/
Opthamology
•General
•Reproductive
•Orthopaedics
Example
•Gas masking
•Endotracheal gas
anesthesia
•Nebulization
•Skin
•Conunctiva
•Subconjunctival
•Eye/ Ear
•Anticonvulsa
nts
•Analgesics
•Antiemetics
•CIDR, PRID
•Nitroglycerin
•Fentanyl
Functions
•Rapid blood levels
•+/- systemically
•Absorbed
lower than
oral (small SA
or
formulation:
solid, liq.,
semi-solid)
• Variable
•Constant plasma
levels: delivered
slowly and
continuously over
an extended
period of time
Pros
•Anesthesia
•Emergency
procedures
•Respiratory
disease
•Good local effect
•Easy to
administer
•If toxic IV
•Fractious
animals
•Poor
condition of
patient
•First dissolve
than penetrate
•May be irritating
•Chew/ lick/ rub
•Clip for good
skin contact
•Local
irritation
Cons
•Quickly
eliminated from
body
•Depends on
formulation,
physiology, age,
phase of estrous
cycle
•Retention of
unit
•Mixed with
chemicals to
enhance skin
penetration
(blood)
•Skin irritation
Nonparenteral Administration
Routes
• Delivered directly to the GI tract
• Most convenient (owner can do)
• Before entering the bloodstream: oral drug must
be released from the dose form, transported across the GI tract,
and passed through the liver (reduces amount)
• Long duration of activity, slow onset of action
• Relatively safe (less likely for adverse effects)
• No need for sterility
• Gastric acid and disease may affect absorption rate
• Ruminants have questionable absorption
• Must get through GI mucosa
Oral Meds
• Orally administered drug gets into bloodstream
– Dissolving the drug form (solid / liquid)
• Solid: tablet (sustained released, molded), capsule,
powder, bolus, lozenges
• Liquid: Solution, suspension, emulsion
– Transport across GI tract
– Drug passage through the liver
Oral Meds
• Released from its form (tablet, capsule, liquid,
powder, bolus, lozenges) after the animal
swallows it
• Tablets
– Disintegrate in stomach liquid
– Some tablets have an enteric
coating (don’t break),
meaning the drug does
not dissolve (neutral/ alkaline pH)
until it reaches the SI
– They cause less stomach irritation
Oral Meds
• Sustained released tablets
– Coated so released in controlled fashion
– Crystal of KCL on wax,
microencapsulated drug (small drug particles with
polymer coating)
• Molded tablets
– Soft, chewable
– Mixed with lactose, sucrose,
or dextrose and frequently a
flavoring (Heartguard)
Oral Meds
• Capsules
– Gelatin shell (dissolves in stomach liquids)
– Holds in the powdered or liquid medication
• Boluses are large rectangular tablets used in large
animals
• Lozenges are in a hard, slow-release form. Not
practical in animals (they will chew it)
• Powders are dry and granulated and mixed with inert
bulking and flavoring agents for dilution. These are
easily mixed with food
Liquid Oral Drug
• SOLUTIONS- drug is dissolved in liquid. Will not
settle out if left standing (syrups, elixirs)
• SUSPENSIONS- finely divided undissolved
substance dispersed in water (shake the container to
distribute)
• EMULSION – fine droplets of oil in water or vice
versa. Separate if standing for long periods of time.
Must shake vigorously
• All 3 can be mixed with food. Liquids don’t irritate
the stomach as much as solid meds because they
don’t settle out in a focal spot.
Liquid Oral Drug
• Solutions, Suspensions and Emulsions
– Mixed with food
– Don’t irritate the stomach as much as solid meds
because they don’t settle out in a focal spot
– Not as accurate dose in food
– Option for aggressive patient
Transport Across GI
• Species anatomy can affect drug absorption
– Ruminants
• Longer to respond ( 3days)
• Can be ineffective
• Longer to reach therapeutic
levels in blood
– Horses: modified mono
gastic, continuous grazers so
some drugs absorbed rapidly
others slowly
– Monogastric
Liver
After the drug is absorbed by the GI tract, it
must pass through the liver. The liver affects
blood levels because it can alter a drug. BE
CAREFUL with drug choices when the liver is
not functioning properly.
General Guidelines
• Table 3-5: Pharmacological Aspects of
Nursing Care
Therapeutic Range
• Drug Factors
–Route of administration
–Drug dosage
–Dosage interval
Dose
DOSE = the amount of drug administered at one
time to achieve the desired effect
mL, cc, mg, Tablets
Drug Dose
– LOADING DOSE –
• the initial dose of a drug given to achieve drug levels in
the therapeutic range in a short period of time
• Large amount of drug initially / normal amount more
often
– MAINTENANCE DOSE – dose maintains
drug in the therapeutic range
– TOTAL DAILY DOSE – amount of drug
given in 24 hours (ex: 1200 mg per day)
Drug Dosage
– DOSAGE – amount of drug per animal’s body
weight (ex: 5 mg/kg, 1g/lb, 60 mEq/kg )
– DOSAGE INTERVAL – how frequently the
dosage is given (SID, BID, TID, Q24H, Q12H,
Q8H, Q6H, QD, Q2D, PRN, etc)
– DOSAGE REGIMEN (30mg/kg tid, po X 7 days)
•
•
•
•
Dosage
Dosage interval
Administration route
Duration of treatment
Drug Toxicity
• Drug toxicity may be due to human error and/or
accident
• Drug toxicity may be related to side effects of the
drug
• Examples of drug toxicities:
–
–
–
–
–
–
Outright overdose
Relative overdose
Side effects
Accidental exposure
Interaction with other drugs
Incorrect treatment
Your patient is reacting to the
medication, now what?
• Directly remove the drug
– Wash off the topicals, induce emesis for those
ingested
• Activated charcoal to bind what cannot be
vomited
• IV fluids to support the kidneys
• Give an antidote if there is one
• Provide care until the animal is through the
toxicity
KEEP YOUR PATIENTS SAFE!