Chapter 3 Principles and Methods of Drug Administration Copyright © 2011 Delmar, Cengage Learning.

Chapter 3

Principles and Methods of Drug Administration

Copyright © 2011 Delmar, Cengage Learning

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


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


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


Six Rights of Drug Administration

• To provide safe drug administration, the six rights of drug administration should be followed:– The right drug– The right dose– The right time– The right route– The right patient– The right documentation


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


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


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


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


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


The Right Documentation

• The right documentation requires the person administering the drugs must immediately record the appropriate information about the drug given– The drug– Dosage administered– Time and date administered– The route and site– Patient’s response– The vet’s signature or initials


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


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


Keeping Drugs in the Therapeutic Range

• Three major drug factors keep drugs in their therapeutic range:– Route of administration– Drug dose– Dosage interval


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


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)


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


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


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


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


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


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


Vaginal Drug Administration

• The vaginal route is a potential administration route for therapeutically important macromolecules.

• Successful delivery may be challenging because of poor absorption


Vaginal Drug Administration

• 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

• 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


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


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


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


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


Counteracting Drug Toxicities

• Veterinary staff must act quickly to counteract any problems caused by drug treatment

• Some ways to treat drug toxicities:– 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


Chapter 3 Principles and Methods of Drug Administration Copyright © 2011 Delmar, Cengage Learning.

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