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Principles of Veterinary Drug

Use

Presented by Audrie McNab,Veterinarian

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The veterinary prescriptionoriginates with a veterinarian or afarmer/owner decides on a particulartreatment.

Administration of said drug (s) isagain shared by the above two.

Your Role as Pharmacist:

Formulation and dispensing

Proactive role in prophylaxis andtreatment of parasitic diseases

Advising clients as to what isavailable for their animalstreatment

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Why are drugs used in

animals???

The safeguarding of Animal Health for:

1. Relief of pain and suffering

2. Gains in food production capacity

3. The control of animal infections

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In Veterinary Medicine, one should employ:

1. Preventive strategies, such as appropriatehusbandry and hygiene, routine healthmonitoring, and immunization, should be

emphasized.- establishment of the definitive diagnosis- recognition of the many factors that influence the

disease process viz.

Genetics

NutritionHousing

Management

Health

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These principles govern drug use

2. Other therapeutic options should be considered prior

to or in conjunction with antimicrobial therapy.

e.g. acidification of feed or water, electrolyte therapy,

supportive care (e.g., antipyretic therapy).

3. Judicious use of antimicrobials, when under the

direction of a veterinarian, should meet all

requirements of a veterinarian-client-patientrelationship.

Antimicrobials represent a powerful therapeutic option.

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These principles govern drug use

4. Extra-label antimicrobial therapy must be prescribed

only in accordance with the veterinarian.

viz. The following drugs are expressly prohibited for extralabel

use in food animals: chloramphenicol, clenbuteral, diethylstilbestrol,dimetridazole, ipronidazole, other nitroimidazoles, furazolidone,

nitrofurazone, sulfonamide drugs in lactating dairy cows (except

approved use of sulfadimethoxine, sulfabromomethazine, and

sulfaethoxypyridazine), fluoroquinolones, glycopeptides (e.g.,

vancomycin), and phenylbutazone in female dairy cattle 20 months of

age or older.

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These principles govern drug use

5. Utilize culture and susceptibility results

to aid in the selection of antimicrobials when

clinically relevant.

Clinical outcomes, history, and experience should also

be used in the selection of antimicrobials.

6. Therapeutic antimicrobial use should be

confined to appropriate clinical indications.

Accuracy in diagnosis is important

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These principles govern drug use

7. Therapeutic exposure to antimicrobials should

be minimized by treating only for as long as

needed for the desired clinical response.Therapeutic exposure involves both dose and duration.

Continued use of antimicrobials in chronic, non-responsive

clinical cases should be discouraged.

Withdrawal times must always be considered during the

selection of antimicrobials.

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These principles govern drug use

8. Limit therapeutic antimicrobial treatment to ill or at

risk animals, treating the fewest animals indicated.

- Consider group morbidity and mortality rates when deciding

whether or not to initiate herd, group, or individual therapy.

- Consider the herd health history for the therapeutic use of

antimicrobials in the control and prevention of disease.- When these factors are appropriately considered,

preventative therapy is a judicious use of antimicrobials.

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These principles govern drug use

9. Minimize environmental contamination

with antimicrobials whenever possible.

Water medicators and feeders need to be

properly adjusted to deliver the desired dose

and to avoid spillage and waste.

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Glossary of TermsAntibiotic -- a chemical substance produced by a

microorganism which has the capacity, in dilute solutions,

to inhibit the growth of or to kill other microorganisms.

Antimicrobial -- an agent that kills bacteria or

suppresses their multiplication or growth. This includesantibiotics and synthetic agents. This excludes ionophores

and arsenicals.

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Glossary of TermsNarrow Spectrum Antimicrobial -- an antimicrobialeffective against a limited number of bacterial genera; often

applied to an antimicrobial active against either Gram-positive

or Gram-negative bacteria.

Broad Spectrum Antimicrobial -- an antimicrobialeffective against a large number of bacterial genera; generallydescribes antibiotics effective against both Gram-positive and

Gram-negative bacteria.

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Glossary of TermsAntibiotic Resistance-- a property of bacteria that confersthe capacity to inactivate or exclude antibiotics or a mechanism

that blocks the inhibitory or killing effects of antibiotics.

Immunization-- the process of rendering a subject immuneor of becoming immune, either by conventional vaccination orexposure.

Monitoring -- monitoring includes periodic health surveillance

of the population or individual animal examination.Therapeutic-- treatment, control, and prevention of bacterial

disease.

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Glossary of TermsExtralabel -- actual use or intended use of a drug in an

animal in a manner that is not in accordance with the approved

labeling.

This includes, but is not limited to, use in species not listed in

the labeling, use for indications (disease or other conditions)

not listed in the labeling, use at dosage levels, frequencies, or

routes of administration other than those stated in the labeling,

and deviation from the labeled withdrawal time based on thesedifferent uses.

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Glossary of TermsWithdrawal Period/Timethe time which passes

between the last dose given to the animal and the time when

the level of residues in the tissues or products fall below the

minimum residue limit (MRL).

Until this period has elapsed, the animal or its products (milk,

eggs, cheese) must not be used for human consumption.

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Types of Veterinary Medicines

Prophylactic medicines designed to prevent

disease and parasitic infestation and include:

a) endoparasiticides

b) ectoparasiticides

c) endectocides

d) vaccines

e) antiseptics

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Types of Veterinary MedicinesTherapeutic medicines these are designed to treat

disease and include:

a) antibiotics

b) hormones

c) sedatives

d) cardiovascular drugs

e) drugs acting on gastrointestinal tract

f) immunological products

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Types of veterinary medicines

Other medicines to help the veterinarian/farmer

a) digestive enhancers

b) anaesthetics includes painkillers andeuthanasia products

c) dietary supplements used for treating or

prevention of specific dietary deficiencies

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General Characteristics of Veterinary

medicinesSafety for humans

Intrinsic toxicity organophosphate products

- drug residues e.g. MRSA,VRE

Environmental safety faecal residues; waste dips

Risk during administrationStrict observance of Withdrawal Periods

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General Characteristics of Veterinary

medicines

Safety issues for animals

Toxicity a number of adverse reactions are possible as aresult of a drugs intrinsic toxicity

a) allergies i.e. nausea, vomiting, urticaria; attentuated andinactivated vaccines may cause a hyposensitivity treatable

with adrenaline SQ; ivermectin in dog breeds as the Collie;

acepromazine in the Boxer

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General Characteristics of Veterinary

medicinesSafety issues for animals contd.

b) Renal changes (aspirin, griseofulvin in dogs)

c) CNS effects (glucocorticoids, clindamycin)

d) Dermatological eczema, alopecia( coal tar

shampoos, prednisonee) Oculara transient blue eye with the use of

certain canine vaccines

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General Characteristics of Veterinary

medicines Safety issues for animals contd.

Injury from administration method reuse of injection needles

(blood-borne transmission/abscessing); local allergic responses

to adjuvants/ vehicles; physical and/or infection from incorrect

use of intrammary tubes, balling guns and drenching

equipment; risk of adverse reactions from topically applied

creams and ointments

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General Characteristics of Veterinary

medicines

Convenience of use

Medicines that come ready for administration are convenient touse and preclude errors.

Calculating the dose can be difficult in OTC products esp.

when the dose is given w.r.t. weight. Tricky is determining a

small/medium/large dog and varies with manufacturer.Refrigerator may be necessary for storage

Oral routes preferable to injection route

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Convenience of use contd.

Drugs must be appropriately formulated drugs must be

appropriately formulated to ensure ease of administration eg.

Topical flea preparations are to be water resistant;

coccidiostats for poultry must be water soluble

General Characteristics of Veterinary

medicines

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General Characteristics of Veterinary

medicines

Palatibility

A nightmare for unpalatable

medicinal products, hence

the flavoured dosage formsof drugs e.g. tuna; pill pockets

Administration Route

the nature of the animal must be taken into consideration

eg fish live in water, thus drug administration must be viawater; or intravenous administration is to be considered fora moribund, comatose patient; aerosolization of poultrymedication.

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Cost

Economic decisions to cull in farm animals vs. pet owners

emotional link.Efficacy

All medicines must do what they clam to do when used as

instructed on the label.

Withdrawal period

Strict observance of this time period w.r.t. food animal drug

use.

General Characteristics of Veterinary

medicines

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Main Chemical Groups of Veterinary

Medicines

Primary Focus:

1. Parasiticides

2. Antimicrobials3. Rehydration and electrolyte balance products

4. Antiseptics and disinfectants

5. Vaccines

6. Prebiotics and Probiotics

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ROUTES OF DRUG

ADMINISTRATION IN

ANIMALS

Wednesday, October 12, 2011 Audrie F.E. McNab, Veterinarian 28

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Wednesday, October 12, 2011 Audrie F.E. McNab, Veterinarian 29

Medicating Animals Cattle:

http://www.youtube.com/watch?v=Am-3L3IVQBs&feature=related

http://www.youtube.com/watch?v=JuX5SKXEs4k

Horses:

http://www.youtube.com/watch?v=UaSWtafCqAA&NR=1

Cats:

http://www.youtube.com/watch?NR=1&v=3VnLcmZwEag

Dogs:

http://www.youtube.com/watch?v=GgAuvoxu5Ic

Subcutaneous fluid administration

http://www.youtube.com/watch?v=C843OGxIgJs

http://www.youtube.com/watch?v=Am-3L3IVQBs&feature=relatedhttp://www.youtube.com/watch?v=JuX5SKXEs4khttp://www.youtube.com/watch?v=UaSWtafCqAA&NR=1http://www.youtube.com/watch?NR=1&v=3VnLcmZwEaghttp://www.youtube.com/watch?v=GgAuvoxu5Ichttp://www.youtube.com/watch?v=C843OGxIgJshttp://www.youtube.com/watch?v=C843OGxIgJshttp://www.youtube.com/watch?v=GgAuvoxu5Ichttp://www.youtube.com/watch?NR=1&v=3VnLcmZwEaghttp://www.youtube.com/watch?v=UaSWtafCqAA&NR=1http://www.youtube.com/watch?v=JuX5SKXEs4khttp://www.youtube.com/watch?v=Am-3L3IVQBs&feature=relatedhttp://www.youtube.com/watch?v=Am-3L3IVQBs&feature=relatedhttp://www.youtube.com/watch?v=Am-3L3IVQBs&feature=related

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Routes of AdministrationMany exist

Each has disadvantages and advantages

Selection of a particular route depends on: patient size temperament

disease state

unique species characteristics

characteristics and commercial formulation of the drug

knowledge and expertise of administrator

cost of drug

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Routes of Administration

intravenous

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Routes of Administration

Subcutaneous Intramuscular, intradermal , intranasalID

ID allergy testing & localanaesthetics;

SQ vaccine use

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Intratracheal, intraosseous, intraperitoneal

Topical opthalmic, aural

Oral, Oro-oesophageal, orogastric

Naso-oesophageal, nasogastric

Transdermal, intrarectal

IntramammaryInhalation

Routes of Administration

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Routes of AdministrationOral (enteral) administration

tablets, capsules, powders, suspensions & solutions

Parenteral administration

IV, IM, IP, SC;epidural, intra-dermal,

Topical (Local)

application to skin and adnexa / mucous membranes

Inhalation (Pulmonary)gases, volatile agents

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Some Advantages /Disadvantages of Routes

ORALconvenient ease of administration, economical, accurateand uniform dosing, less stress (birds); first-pass metabolism,

gag reflexes, restraint necessary, possibility of damage to tissue

and administrator

PARENTERALsterility required, less painful (SQ), ease ofadministration; adverse effects e.g. circulatory collapse, tissue

irritation/sloughing/extra-vasation leading to permanent tissue

loss and damage, erratic absorption, longer duration of action

due to decreased absorption (SQ)

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Routes of AdministrationSome Advantages /Disadvantages of

Routes

TOPICALeasily applied, good for localised treatmentand local effects instead of systemic ones; possibility of

toxicities

INHALATIONdrug delivered directly to target organ(lungs)

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Drug Action

Drugs do not induce different actions in thebody;

they enhance or modify general or specificcellular functions

Drugs also cause two types of effects: TypeA and Type B

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Examples of unique responses

Species Drug Reaction

horses Phenothiazine neuroleptics Permanent penile

paralysis

Monensin Fatal cardiac failure

Tetracyclines, macrolides Fatal colitis

Cats Acetaminophen Fatal centrilobular hepatic

necrosis

Phenolic compounds Marked sensitivity

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Examples of unique responses

Cats Morphine & other opiodanalgesics

excitatory

aminoglycosides Sensitive to neurotoxic

effects

Cattle Xylazine Extreme sensitivity to

depressant effects with

copious vols of saliva

prodxn.

Morphine Excitatory, aberrant

behaviour

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Type A Effects

These reflect excess or diminished butpredictable, pharmacological actions

Are generally dose-dependent

Rarely lead to death

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Type A Effects

Causes of these Type A effects are:

Physiological factors: species, breed, genetics, age,

sex, body weight and surface area, diet, nutritional

status, temperament, relative activity, circadian

rhythms, environmental conditions

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Type A EffectsCauses contd

Dosage form,generic equivalence

Dose rate and deliveryroute

Time and frequency of

administration

Direct drug-drug

interactions

Pharmacokinetic

interactions

Drug-diet interaction

(Pharmacological factors):

Type A Effects Causes contd

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Type A EffectsCauses contd.

toxaemia and pyrexia

shock, electrolyte and acid-base disorders

uraemia and renal disease, hepatopathycardiovascular disease, anaemia, respiratory

disorders

GI disorders, neurological disturbances and impairedimmunocompetence

(Pathological states):

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Type B Effects

These lead to aberrant drug effects

Unrelated to anticipated responses

Independent of dose used

Mortality may be high

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Type B Effects Cause and Form

Genetic differences between animals of same

species and breed (Ivermectin and Collies;

acepromazine and Boxers)

The common form of Type B reaction is Drug

allergy or Hypersensitivity (cats andacetaminophen)

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THANK YOU