Transcript Chapter 3 - Delmar Cengage Learning

Chapter 3
Principles and Methods of Drug Administration
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Safe Drug Use
• All drugs should be considered potential poisons
and given with great care.
• Appropriate administration of a drug includes
– Administration of the appropriate amount of drug
(based on dosage)
– Introduction of the appropriate amount of drug into the
animal’s body
– The amount of drug must also be introduced into the
animal’s body by the appropriate route of
administration
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Safe Drug Use
• In preparing to administer medication, the vet
must ensure cleanliness of all materials used
• Hands, work surface, and supplies must all
be clean
• All supplies needed should be on hand
• Medication should be prepared in an area with
good lighting and minimal distractions
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Safe Drug Use
• Vets and techs must know all components of a
drug order
• Any orders that are not complete, unclear, or
that give a dosage outside the recommended
range should be questioned
• All verbal drug orders should be documented as
soon as possible
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Six Rights of Drug Administration
• To provide safe drug administration, the six
rights of drug administration should be followed:
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The right drug
The right dose
The right time
The right route
The right patient
The right documentation
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The Right Drug
• Means the patient received the drug that was prescribed
• The label on the container should be read three times
• When preparing for administration of drug, it should also
be checked three times
• Understanding the reason why the patient is receiving
the drug is important
• Never give a medication from a container that is
unlabeled
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The Right Dose
• The right dose is the dose prescribed for this
particular patient
• Vets and techs must calculate each drug dose
accurately
• Before calculating a drug dose, an estimate of
the answer based on prior knowledge should
be known
• When in doubt, have the dose recalculated by
another vet tech
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The Right Time
• The right time is the time at which the dose
should be administered
• Daily drug doses are given at specific times
during the day
– This is done to keep plasma levels at the proper level
to cause the desired effect
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The Right Route and Technique
• The right route is the proper route of
administration, so that the patient takes the
whole dose at one time
• It is important to use aseptic techniques when
administering drugs
• Drugs should also be administered at the
appropriate site
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The Right Patient
• The right patient means the vet tech makes certain that
the medication is given to the proper patient
• If patient is in a cage check the cage card and ID band
• If the patient is in the exam room, identify the patient by
name
• When dispensing medication, read the patient’s name to
the owner to ensure the right animal gets the right
medication
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The Right Documentation
• The right documentation requires the person
administering the drugs must immediately record
the appropriate information about the drug given
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The drug
Dosage administered
Time and date administered
The route and site
Patient’s response
The vet’s signature or initials
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The Right Documentation
• The right documentation is a legal and safety
obligation
• Documentation is the primary method used to
communicate drug administration between
professionals
• It should also be documented if an owner
refuses drug treatment for his/her animal
including the reason for refusal
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The Therapeutic Range
• All drugs should be considered potential
poisons and should be dispensed and
given with great care
• The therapeutic range of a drug is the drug
concentration in the body that produces
the desired effect in the animal with
minimal or no signs of toxicity
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Keeping Drugs in the
Therapeutic Range
• Three major drug factors keep drugs in
their therapeutic range:
– Route of administration
– Drug dose
– Dosage interval
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Route of Administration
• Parenteral drugs are given by a route other than
the gastrointestinal tract
• Nonparenteral drugs are given through the
gastrointestinal tract
• Factors that affect the route of drug
administration include:
– Drug causes one effect when given parenterally and
another nonparenterally
– Water-insoluble drugs can be given IM,
but not IV
– Some drugs are destroyed by stomach acid and
cannot be given orally
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Injectable Routes of Administration
• Injectable routes are parenteral
• Most common injectable administration
routes are IV, IM, and SQ
• Drugs given by injectable administration
routes may be aqueous solutions or
emulsions (mixtures of two immiscible
liquids)
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Injectable Routes of
Administration (IV)
• Drugs given IV have rapid onset of action, higher
initial body levels of drug, and shorter duration of
activity
• IV injection techniques include bolus
administration, intermittent therapy, and infusion
of fluid
• In most cases, IV drugs should be given slowly
• All air bubbles must be removed from the drug
before administration to avoid causing air emboli
and tissue damage
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Injectable Routes of
Administration (IM)
• Drugs given IM have relatively rapid onset of action and
longer duration of activity than IV drugs
• Absorption rate depends on drug formulation
• IM-injectable drugs may be in a substance that delays
absorption; these are referred to as repository or depot
preparations
• IM drugs can be in aqueous solutions or suspensions
– Solutions are clear liquids that contain one or more solvents and
one or more solutes
– Suspensions are liquid preparations that contain solid drug
particles suspended in a suitable medium
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Injectable Routes of
Administration (SQ)
• Drugs given SQ have slower onset of action and longer
duration of activity than IV and IM drugs
• Absorption rate may be altered by the vehicle in the
preparation
• Larger amounts of solutions can be given SQ; amount
given should be based on animal species involved
• Pellets can also be implanted into the subcutaneous
space
• The rate of absorption of SQ fluid can be manipulated by
temperature
– Applying heat to the area increases the rate of absorption
– Applying cold to the area decreases the rate of absorption
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Intramammary Injections
• Typically have fast and even distribution
and a low degree of binding to udder
tissue
• Results in lower concentrations of drug
residues in the milk
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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
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Rectal Drug Administration
• May be an alternative for delivering drugs
because of dangers presented to the vet staff or
because of the 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
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Vaginal Drug Administration
• The vaginal route is a potential
administration route for therapeutically
important macromolecules.
• Successful delivery may be challenging
because of poor absorption
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Vaginal Drug Administration
• The rate and extent of absorption depends on
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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
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Transdermal Drug Administration
• Transdermal drugs are delivered through a
patch on the skin
• Through the patch, the passes from skin to
bloodstream allowing the drug to be delivered
slowly and continuously
• Skin irritation is one side effect
• Only drugs needed in relatively small daily
doses can be given through patches
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Nonparenteral Administration
Routes
• Oral administration delivers the drug directly to the
animal’s gastrointestinal tract
• Before entering the bloodstream, an oral drug must be
released from the dose form, transported across the GI
tract, and passed through the liver
• Oral drugs usually have slower onset of action, longer
duration of activity, and absorption rates that may be
affected by the type of digestive tract and/or GI disease
• Oral drugs may be tablets, capsules, boluses, powders,
solutions, suspensions, or emulsions
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Drug Dose
• The dose of a drug is the amount of drug administered at
one time to achieve the desired effect (can be in mL, cc,
mg, g, tablets, etc.)
• Loading dose: initial dose of drug given to get the drug
concentration up to the therapeutic range in a very short
period of time
• Maintenance dose: dose of drug that maintains or keeps
the drug in the therapeutic range
• Total daily dose: total amount of drug delivered in 24
hours
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Drug Dosage
• The dosage of a drug is the amount of drug per
animal species’ body weight or measure
– Examples include mg/kg or g/lb
• Dosage interval: how frequently the dosage is
given
– Examples include BID or TID
• Dosage regimen: dosage interval and the
dosage together
– Examples include 30 mg/kg TID and 5 g/lb BID
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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:
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Outright overdose
Relative overdose
Side effects
Accidental exposure
Interaction with other drugs
Incorrect treatment
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Counteracting Drug Toxicities
• Veterinary staff must act quickly to counteract
any problems caused by drug treatment
• Some ways to treat drug toxicities:
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Removal of the offending drug
Enhancing drug removal by the animal
Counteracting with an antidote
Providing symptomatic care or nursing care until the
toxicity signs have diminished
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