INTRODUCTION TO PHARMACOLOGY

            The word pharmacology is derived from Greek words Pharmacon (drug) and logos (a discourse / treatise). Pharmacology is the science of drugs. It is an experimental science dealing with the properties of drugs and their effects on living systems. It encompasses all aspects of knowledge about drugs, but most, importantly those that are relevant to effective and safe use for medicinal purposes. The word drug is derived from the French word drogue, a dry herb. A drug is defined as any substance used for the purpose of diagnosis, prevention, relief or cure of a disease in man / animals. Disease is the state, which appears due to the deviation(s) of normal physiological function. Drugs interfere with this altered function and reverse it to the normal. Therefore pharmacology is considered to be a bridging medical science in that its study is dependent on an understanding of anatomy, physiology, microbiology, biologic and organic chemistry, and mathematics. Through understanding of pharmacology, toxicology and pathology is a prerequisite for the study of internal medicine, surgery, and other clinical subjects.

Role of pharmacology in veterinary medicine

Pharmacology like pathology, is a bridging medical science in that its study is dependent on an understanding of anatomy, physiology, and microbiology, biologic and organic chemistry and mathematics. Conversely, thorough understanding of pharmacology, toxicology and pathology is a requisite to studies of internal medicine, surgery and other clinical subjects. It should be borne in mind that there is no completely "safe" drug unless it is a pharmacologically inert substance.

The list furnished below gives certain points to be considered before choosing a drug for administration.

1. What is the therapeutic goal to be achieved? what are the specific pathological processes that are expected to be altered by the use of the drug? and is it absolutely necessary to use this or any other drug?

2. By what routes the drug can be administered? which route is going to be chosen? and what are the advantages and disadvantages of choosing that route?

3. What dosage form is likely to be used?

4. What dose is generally recommended? and are there any precautions for use of the drug?

5. What is the dosage interval? and is it frequent enough to maintain therapeutic concentration? or will it be too frequent to create cumulative toxicity?

6. What is the probable duration of therapy?

7. Is the drug approved for food animals? and what is the withdrawal time if food animals are to be treated?

8. What will be the cost of treatment? and will the cost exceed the value of the animal?

9. What special precautions are to be observed to enhance its effectiveness or safety?

10. What are the contraindications to the use of this drug?

11. What adverse reactions are likely to be noticed?

12. What course of action is to be taken if adverse reactions are noticed?

13. How can the results of therapy be evaluated?

Therapeutic regimen whose basis lies outside the domain of science are, of course, very much active today and they are even gaining ground under the general banner of alternative or holistic medicine. Mostly they reject the medical model which attributes disease to an underlying derangement of normal function that can be defined in biochemical or structural terms detected by objective means and influenced beneficially by appropriate chemical or physical intervention. They focus mainly on subjective malaise, which may be disease associated, or not. Abandoning objectivity in defining and measuring disease goes along with a similar departure from scientific principles in assessing therapeutic efficacy, with the result that principles and practices can gain acceptance without satisfying any of the criteria of validity that would convince a critical scientist and that are required by law to be satisfied before a new drug can be introduced into therapy. Public acceptance alas, has little to do with demonstrable efficacy.

 

Scope of Pharmacology

As with other biomedical disciplines, the boundaries of pharmacology are not sharply defined nor are they constant. Within this main subject pharmacology fall a number of compartments.

Pharmacology today with its various subdivisions

1. Veterinary Pharmacology      

2. Systemic Pharmacology        i)  Neuro pharmacology,            ii) Psycho pharmacology,

iii) cardiovascular pharmacology, iv)  Respiratory Pharmacology,

v) Gastro-intestinal pharmacology,

vi) Ruminant Pharmacology, vii) Reproductive pharmacology,

viii) Endocrine pharmacology, ix)  Immuno pharmacology, x) Dermato pharmacology, xi)  Occular pharmacology, xii) Behavioral pharmacology, xiii)  Dental pharmacology, xiv) Autacoidal pharmacology         

3. Molecular Pharmacology,       4. Biochemical Pharmacology, 5.Pharmacometrics, 6.Pharmacogenetics, 7. Pharmacogeneomics, 8. Experimental pharmacology, 9.Comparative pharmacology, 10. Clinical Pharmacology, 11.Geriatric pharmacology, 12. Paediatric Pharmacology,

13. Pharmacoepidemiology,14. Pharmacoeconomics, 15. Production Pharmacology,

16. Chemotherapy, 17. Toxicology, 18. Chrono-Pharmacology, 19. Ethno-Pharmacology