Introduction to Veterinary Pharmacotherapy

PST 06107

Basic

Veterinary Pharmacology

Session 1: Introduction to Veterinary Pharmacology

Learning Tasks

By

the end of this session students are expected to be able to:

Define terminologies used in veterinary pharmacology

Outline the therapeutic classes of veterinary medicines

Describe principles and concepts applied in veterinary pharmacology

Explain the sources veterinary medicines

Outline the basic concepts in veterinary toxicology

Explain the importance of veterinary pharmacology in the management of common animal diseases

General Principles and Concepts of Veterinary Pharmacology and Toxicology

Veterinary Pharmacology is the study of substances that interact with living systems through chemical processes, especially by binding to regulatory molecules and activating or inhibiting normal body processes in

animals

Veterinary

pharmacology is concerned with the use of drugs for diseases and health problems unique to

animals

The

sources of

veterinary

medicines are also similar to the sources of human medicines namely plants, animals, minerals and synthetic sources

General Principles and Concepts of Veterinary Pharmacology and

Toxicology

Cont

…

The therapeutic classes of veterinary medicines include antibiotics, antifungal,

antiviral,

anti-inflammatory drugs, growth promoters,

ant parasitic

drugs, insecticides and

tranquilizers

The

principles and concepts of veterinary pharmacology are similar to human

pharmacology

They

involve Pharmacokinetics and Pharmacodynamics

General Principles and Concepts of Veterinary Pharmacology and Toxicology

Cont

…

Pharmacodynamics is the study of cell/tissue responses and selective receptor effects.

The

significant difference in veterinary pharmacology is the species variations that need to be

considered

These

variations have significant influence on pharmacokinetics and pharmacodynamics of veterinary medicines

Toxicology is the study of poison and their effects on normal physiologic mechanisms

General Principles and Concepts of Veterinary Pharmacology and Toxicology

Cont

…

It

is important to understand the more commonly encountered toxins and to treat affected animals

accordingly

When treating an intoxicated animal, the general rule to remember is that, “

treat the animal not the poison

”

Toxicity is the quality of being poisonous (dose of poison that elicits a

response)

Toxicosis is the clinical syndrome associated

with

exposure to a poison e.g. acetaminophen

toxicosis

General Principles and Concepts of Veterinary Pharmacology and Toxicology

Cont

…

Toxins

that affect the more commonly domestic species are extremely diverse

The types of toxins often encountered include;

Metals,

mycotoxins

, feed-related intoxications, pharmaceutical agents, pesticides (insecticides, herbicides),

biotoxins

(plants,

poisononous

animals and insects, bacterial toxins)

For

toxicosis

to occur,

there

must be a dose-related response, the greater the dose the more likely that

toxicosis

will occur

General Principles and Concepts of Veterinary Pharmacology and Toxicology

Cont

…

Some toxins exhibit a steep dose-response relationship and are considered highly toxic

To cause intoxication, a substance must be absorbed and delivered to the site of action at a concentration high enough to elicit a physiologic response e.g. presence of a poisonous plant in a pasture is not enough; there must be evidence of consumption of these plants

Different animals in a herd may consume different plants or forage

There are individual and species variations in susceptibility to toxins

The clinical signs observed must correlate with the suspect plant

General Principles and Concepts of Veterinary Pharmacology and Toxicology

Cont

…

Toxicokinetics

This is the study of the metabolic processes that occur after exposure to a toxin (absorption, distribution, biotransformation, and elimination)

It involves the mathematical description of

the movement

of a toxin into the body (absorption), to the target organs (distribution) and out of the body (elimination)

Concentration of a toxin at the site of action depends on;

Dose, physicochemical properties of the toxin or drug, absorption, distribution, specific tissue affinity, rate of metabolism, rate of

elimination

General Principles and Concepts of Veterinary Pharmacology and Toxicology

Cont

…

The fate after exposure to toxins is influenced by;

Toxins or drug factors

Host factors or physiologic factors

There are animal factors including age, organ perfusion, organ function (hepatic, renal), membrane permeability, pH of tissue or compartment, species and gastrointestinal anatomy and physiology

Activity: Small Group Discussion

What

is pharmacokinetics?

General Principles and Concepts of Veterinary Pharmacology and Toxicology

Cont

…

Pharmacokinetics is the study of drug absorption, distribution, biotransformation (metabolism), and

excretion

Pharmacokinetic

processes affect the route of administration, doses, dose intervals, and toxicities of drugs given to animals

The

following are the importance's of Veterinary Pharmacology

Helps

in understanding the mechanism of action of veterinary medicines

Helps in the determination of correct indication and dosage of veterinary medicines

Helps to identify and respond to drug interactions, contraindications and adverse drug reactions related to veterinary medicines accordingly

Helps in understanding of the disposition processes in the body including absorption, distribution, metabolism and elimination of veterinary medicines

These will help students learning veterinary pharmacology to dispense right drug to the right animal, at right dose, by right route and at right time

Key Points

Veterinary

pharmacology is the study of medicines which are used in animals, poultry and fish

Principles and Concepts of Veterinary Pharmacology includes pharmacokinetics and pharmacodynamics

Veterinary Pharmacology is important in the pharmacological treatment of veterinary diseases

Toxicology is the study of poison and their effects on normal

physiologyic

mechanisms

Evaluation

What

is veterinary pharmacology?

What are principles and concepts of veterinary pharmacology?

What is importance of veterinary pharmacology?

What is toxicology?

References

Riviere

J. E.,

Papich

M. G. (2009).

Veterinary Pharmacology and Therapeutics

(9th Ed) Iowa, Wiley-

Blackwel

Publishers

Hsu

W. H. (2008).

Handbook of Veterinary Pharmacology

(1st Ed) Iowa, Wiley-

Blackwel

Publishers

Kuafmann

J, (1996).

Parasitic infections of domestic animals

, (2nd

ed

).Berlin,

Birkhäuser

Verlag

Press

Hoare

E. W. (2013).

A manual veterinary therapeutics & pharmacology

(2nd

ed

),New

York, Forgotten Books

Press

Maddison

. J. (

ed

) (2008

). Small Animal Clinical Pharmacology

, (2nd

ed

). Philadelphia, Saunders Elsevier Limited

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