1. Principles and Methods of Drug Administration
CHAPTER 3
L. VanValkenburg, RVT, BAS

2. Safe Drug Use All drugs are potential poisons.
Veterinarian and RVT are accountable for safe drug administration
Know components of drug order and question anything that is not complete, is unclear, or does not make sense.
Verbal drug orders should be documented ASAP.
When preparing and administering meds:
Gather supplies first! 
Clean hands, clean supplies, etc.
Well-lit work area with minimal distractions

3. The Six “Rights” of Proper Drug Administration
Right Drug Right Dose Right Time Right Route & Technique Right Patient Right Documentation

4. The Right Drug
“The right drug” means the patient received the drug that was prescribed.
When filling a prescription or preparing to administer a drug, read label on the container 3 times!
Never give a medication from a container that is unlabeled
It is important to understand why the patient is receiving the drug
Convenia vs. Cerenia
Prednisone vs. Prednisolone

5. The Right Dose
The right dose is the dose prescribed for a particular patient
DVMs and RVTs must calculate each drug dose accurately.
Before calculating a drug dose, an estimate of the answer based on prior knowledge should be predicted.
When in doubt, have the dose recalculated by another DVM or RVT.

6. The Right Time
The right time is the time at which the prescribed dose should be administered
Daily drug doses are given at specific times during the day to keep plasma levels within desirable concentrations.
Do you know what SID, BID, TID, and QID mean?
What about q24H, q12H, q8H, and q6H?
PRN?

7. 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
Drugs should also be administered at the appropriate site in order to obtain the desired effect.
Some routes of administration are not feasible for some animals.

8. The Right Patient
The right patient means the RVT or DVM 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.

9. The Right Documentation
The right documentation requires the person administering the drugs must immediately record the appropriate information about the drug given
Name of drug
Dosage administered
Time and date administered
The route and site of administration
Patient response
DVM signature or initials

10. The Right Documentation
The right documentation is a legal and safety obligation
“If it was not documented, it was not done.”
Legally, controlled substances must also be recorded in a drug log.
It should also be documented if an owner refuses drug treatment for his/her animal including the reason for refusal

11. Informed Consent
Without the client’s consent, the medication cannot be given!
Clients refuse because of:
Lack of knowledge
Misconceptions
Past problems with drug
Inability to ‘cure’ patient
Inability to medicate pet themselves
Financial limitations

13. Our Therapeutic Goal is to:
Achieve drug concentrations at the site of action (target tissue)…
that are sufficiently high enough to produce the intended effect…
without producing adverse drug reactions.
Just right
Too little
Too much

14. Drug Concentrations in the Plasma50 40 30 20 10
But what’s missing here that is needed for this info to be of any use?
Drug Concentration in Plasma (Cp)
mcg/mL
Time since administration of drug
(hours)

15. Drug Concentrations in the Plasma
Toxic Concentrations 50 40 30 20 10
Drug Concentration in Plasma (Cp)
mcg/mL
Therapeutic Concentrations (Therapeutic Range)
Subtherapeutic Concentrations
Time since administration of drug
(hours)

16. Route of administration
Therapeutic Range
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.
Three major drug factors keep drugs in their therapeutic range:
Route of administration
Drug dose
Dosage interval

17. Therapeutic Range
Other factors that play a role in getting and keeping drugs within the therapeutic range include:
Drug properties
Health and physiology of the animal
Maintaining drugs within range involves maintaining a balance among:
Rate of drug entry into body
Absorption of drug
Distribution of drug
Metabolism of drug
Excretion of drug
YOU WILL LEARN MORE ABOUT THESE THINGS IN THE NEXT CHAPTER 

18. Routes of Administration
Oral (PO) (Non-parenteral)
Parenteral routes:
Sublingual
Intradermal (ID)
Via feeding tube
Subcutaneous (SC or SQ)
Intramuscular (IM)
Topical
Intravascular/intravenous (IV)
Transdermal
Intraosseous/Intramedullary
Intranasal
Intraperitoneal (IP)
Inhalation
Intra-arterial (IA)***
Nebulized or volatilized
Intra-articular
Rectal (PR)
Epidural/subdural/intrathecal
Aural
Intracardiac (IC)
Topical ophthalmic
Intramammary

19. Routes of Administration
Parenteral drugs are given by a route other than the GI tract
Nonparenteral drugs are given through the GI tract (orally)
Factors that affect the route of drug administration include:
Drug factors
Patient factors

20. Drug Factors
Some drugs cause one effect when given parenterally and another effect when given non-parenterally.
magnesium sulfate causes muscle relaxation when given IV and diarrhea when given orally
Some drugs are insoluble in water and can be given IM but cannot be injected IV – Always be aware of label!
Some drugs are destroyed by stomach acid and cannot be given orally.
Some injectable drugs must be given very slowly; while others must be given in a bolus.
Cost and availability of drug must also be considered.

21. Patient Factors
Animals that are actively vomiting cannot absorb drugs given orally.
Critically ill patients need to get therapeutic levels of drug into their bodies rapidly.
The animal’s temperament must be considered.
Can/will the owner medicate their animal at home properly with the medication as prescribed?

22. Other Factors to Consider
Is restraint going to be an issue?
Are systemic effects expected or is just a local effect preferred?
What is your time frame?
Does this medication require that special precautions be followed during administration (i.e. gloves, mask)?
Potential side effects?
What is the most convenient route of administration for the owner?

23. Parenteral Administration

24. Designed by Francis Rynd ( ), this instrument was used for deep injections. It is made of steel with an ivory handle, and was manufactured by Weiss. Rynd, an Irish physician, invented the hollow needle in 1844.
Dr Wood first injected a patient with morphine in His wife became the first IV morphine addict. The first recorded fatality from a hypodermic-syringe induced overdose was Dr Wood's wife.
History: Lagniappe

25. Anatomy of a Syringe Bevel Needle Cap Needle hub Luer-lock tip Barrel
Rubber stopper
Scale
Plunger
Flange
Thumb rest

26. Comparison of Common Parenteral Routes of Drug Administration
Intramuscular
90°
Subcutaneous
45°
Intravenous
25°
Intradermal
10°–15°
Epidermis
Dermis
Subcutaneous tissue
Muscle

27. Parenteral Drug Forms Sterilized solutions
Prepackaged syringes with needles
Powders that must be reconstituted with a sterile diluent
Vials (single or multi-dose)
Ampules

29. Intravenous (IV)
RAPID onset of action, HIGHER initial body levels of drug, and SHORTER duration of activity
Drug concentration is predictable.
Injection techniques include: BOLUS administration, INTERMITTENT therapy, and INFUSION of fluid
In most cases, IV drugs should be given slowly
Remove air bubbles!
Usually water soluble drugs; rarely emulsions
Avoid perivascular injection of IV drugs.

30. Intramuscular (IM)
RELATIVELY RAPID onset of action and LONGER duration of activity than IV drugs
Blood levels reliable and typically significant in ~30 minutes.
Absorption rate depends on drug formulation
Repository or depot preparations delay absorption
Ex: Procaine penicillin G and Depo-Medrol (methylprednisolone)
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.

31. Subcutaneous (SC)
SLOWER onset of action and LONGER duration of activity than IV and IM drugs; FASTER onset than PO admin.
Blood levels LESS RELIABLE than IV or IM
Absorption rate affected by the vehicle in the preparation and temperature.
Larger amounts of solutions can be given SQ
Cannot use irritating solutions!
Pellets can also be implanted into the subcutaneous space

32. Intramammary
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
In what instance do you think would we use this route of administration?

33. Other parenteral administration routes are listed in Table 3-1 in your textbook. READ IT…IT IS TESTABLE MATERIAL!!!

34. Local Routes of Administration
Inhalation administration introduces drug to the animal by having it breathe the drug into the lungs
RAPID ABSORPTION; particles diffuse across the alveolar membrane and enter blood capillaries.
Must be AEROSOLIZED, VOLATILIZED, or NEBULIZED

35. Topical medication goes on the surface of skin or mucous membrane
GELS
TINCTURES
OINTMENTS
LOTIONS
CREAMS
POWDERS
PASTES
AEROSOLS
LINIMENTS
Topical medication goes on the surface of skin or mucous membrane
SLOWEST systemic absorption rate
Used for LOCALIZED treatment
Fur and feathers inhibit good skin contact.
Includes OPHTHALMIC and OTIC medications.

36. Rectal
ALTERNATIVE for delivering drugs to animals that present dangers to the vet staff or animals in very poor condition where other methods of admin. are not practical.
Anticonvulsants, analgesics, antiemetics
Local irritation is a potential side effect of rectal drug therapy.
Suppositories are designed for PR admin., however, other drug forms can be successfully admin. PR.

37. Transdermal Delivered SYSTEMICALLY through a patch on the skin
Through the patch, drug passes from skin to bloodstream allowing it to be delivered slowly and continuously (hours, days, or longer)
Plasma levels = relatively CONSTANT
Skin irritation is one side effect
Useful for drugs that are normally eliminated rapidly from the body
Only drugs needed in relatively small daily doses can be given through patches
Typically mixed with chemical to enhance skin penetration
Ex: Fentanyl and Niroglycerin

39. Enteral Administration: Oral Route (PO)
Delivers drug directly to the GI tract
Most CONVENIENT route of admin.; LEAST LIKELY to cause adverse reactions
SLOWER onset of action; LONGER duration of activity
Absorption is not always predictable.
Affected by GI disease, A&P of digestive tract
Before entering the bloodstream, an oral drug must be:
released from the dose form
transported across the GI tract
passed through the liver

40. Solid Dose Forms TABLETS CAPLETS CAPSULES LOZENGES BOLUSES POWDERS
Enteric-coated
Sustained-release (SR)
Scored
MOLDED TABLETS
CAPLETS
CAPSULES
LOZENGES
BOLUSES
Via “balling gun”
POWDERS

42. Liquid Dose Forms
Given via dropper, syringe, or drench or mixed with food.
SOLUTIONS
Syrups (85% sucrose)
Elixirs (sweetened alcohol)
Tinctures (alcohol)
SUSPENSIONS
EMULSIONS
Can you think of any contraindications here?
Advantages/disadvantages of giving with food?

44. Absorption of Oral Drug Forms
Transport across the GI tract determines how long it takes for a drug to enter the bloodstream.
LONGER length of time in ruminants and herbivores (horses, rabbits, etc.)
The more COMPLEX the digestive tract, the LONGER it takes to attain therapeutic blood levels.
Drug passage through liver affects drug concentration in the blood.
“First-Pass Effect”
Liver alters drug and makes it less (or more) active

45. 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

46. 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

47. Drug Toxicity
Drug toxicity may be due to human error or 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

49. Counteracting Drug Toxicity
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 (inducing emesis, administering fluids, etc.)
Counteracting with an antidote
Providing symptomatic care or nursing care until the toxicity signs have diminished