What is pharmacology and the veterinary pharmacon? Definitions
The simplest definition is known of Pharmacology: Pharmacology is the science which deals with the study of the effects of chemicals on organisms.
This definition, however, is too generalized and, therefore, unsatisfactory.
Veterinary pharmacology (pharmakon = medicine, logos = science) is the science which deals with the study drugs in terms of origin, physical structure and chemical composition, kinetics and action in their body and their use in treatment of various diseases in animals.
Pharmacology can be defined also as: the study of the pharmacon's action on living organisms and the Pharmacons as: chemicals that alter the functions of living organisms. WHO defines the term pharmacon, which corresponds to the English term drug, as: A drug is any substance or product that is used or intended to intended to be used to modify or explore physiological systems, or pathological states for the patients' benefit.
Pharmacology is characterized best by the question: Where, how and why act a substance that is researched?
A drug can be defined in the following way: „A medicine is a biologically active substance, or a combination of substances which, after medical science research, through rational administration in humans or in animals, are able to:
a) make possible the recognition, prevention, relief or to prevent the symptoms of disease,
b) to do possible recognition, or influence the structures of organic bodily functions, or behavioral typology of human or animal, as long as it serves the purpose of medicine”.
An ideal drug must submit:
- an accurate activity,
- a known action mechanism,
- a constant efficacy,
- the absence of adverse effects and
And finally, a pharmaceutical drug is: A result of incorporation of a precisely measured amount of one or more active ingredients in a formulation that allows the administration of preventive or curative As you can see, there is no universally recognized definition.
Veterinary use medicines can be defined as: the substance or mixture of chemicals, plant or animal origin, to combat diseases, strengthening health and recovery of physiological unbalanced body functions. In this context it must be enounced the definition of the biological product who: is a preparation of bacterial, fungal, plant, human or animal origin product designated for the prevention or diagnosis of disease.
To avoid the use of drugs that have not been verified by the competent organs, the Romanian health and pharmaceutical law requires the use of Veterinary drugs and biological products catalogue, who include the classification of all curently used drugs and veterinary biological products (also imported) in our country. The introduction or release of the biological products, medicines, appliances, medical equipment, unauthorized and unregistered is prohibited and punished according to Romanian laws. Besides the notion of medicines, in Romanian literature one can meet also the notions of: galenic formulation, preparation, drug form, medical shape, pharmaceutical, remedy (common denomination).
Pharmaceutical substances, as defined in the Pharmacopoeia, are raw materials or drugs of animal, vegetable or mineral extraction, or synthesis, which must meet certain conditions of purity or content provided in the Pharmacopoeia, the transformation of these substances in medicines being done through proper operations. So the sources from which it can be obtained medicines are the: plants, animals, minerasl and synthetic and are known as generic drugs.
A toxic substance means: „any substance who introduced into the body produce general disorder known as poisoning.
Between notions of food, medicine and toxic there is a strong relationship. Thus, many substances that are part of ordinary food (eg salt, glucose, vitamins, minerals, micronutrients, etc.) can be used also as medicines in many deficinencies. A number of medicinal substances (antibiotics, chemotherapy, etc. designed especially for the antibacterial therapy) may be used as feed additives to increase the weight gain in youth animals.
As a general rule: All medicines are absorbed in the body are toxic, usually at higher than therapeutic doses.
Long before the advent of modern pharmacology, Paracelsus (1493-1541) showed that all substances are potential poisons and everything depends only on the dose as dictum: Dosis sola facit venenum.
There are medicines that can be used only for therapeutic very low doses (eg, strychnine, strophantine, atropine, pilocarpine, tubocurarine, etc.), surpassing even faster than the dose causing toxicity. Some substances can meet all the attributes, those of: food - medicine and toxic. For example, salts of calcium, magnesium, iron, copper, cobalt, selenium, administered mainly by injection can cause poisoning by overdose easy. Even some vitamins in large doses can have toxic effects.
Drugs Names and Classification
The questions that have always had to answer the pharmacologists are:
- Which pharmaceutical to be used,
- Which is the correct dose and
- Which is the frequency of the administrations?
It is clear that the answers to these questions depended very much on the pharmacist and manufacturer abilities to prepare from potent raw materials means, secure medicines which can be administered to pacients after recommendations and into account to the safe, curative doses. These ideals have been achieved through the process of standardization of medicines and remedies (a process that continues today). The essential elements of such a system are:
- the definition and adoption of those tests that determine identity, purity and power of a source of medicine, of a substance or a preparation,
- recommendations related to the dose size, frequency of administration and indications for each drug.
But still there is a degree high drug name confusion related because each chemical may be known by a whole variety of names. The „guilt” is of the drugs manufacturers, wich in the aim of protecting their product and for them product standardization, considered advantageous to give the owner or the brand name denominations for each obtained product.
Property Name (Trade Mark™)
It is mostly registered as trademarks. Thus, a chemical compound that forms can be produced in a number of unrelated names by several manufacturers. A greater confusion is created when same medicine may be used as component in relatively large number of preparations of so called shot-gun compounds (compounds that contain several active ingredients). All are products of the same company, but each with a different name property. In an attempt to clarify this situation, the drafting committee of Pharmacopoeias give to each compound a acceptable name (known as official name or generic name).
Under this name, the compound can be found in Pharmacopoeia. This does not necessarily happen immediately after the introduction of a new drug on the market but rather when the product is considered fully verified. Such a „rationalization” is very useful at the national level, but must be considered the international situation, especially in terms of free movement of veterinarians and medicines in the European Community area.
It is mostly derived from the chemical name, usually abbreviated designation compressed because most chemical names are very long and difficult to remember. Moreover, there are some „convention” of the names applied by chemists. Such a compound may have multiple chemical names (different but correct). Therefore, the best solution is represented by an accepted name, approved internationally. However, manufacturers for commercial reasons, prefer to use the brand name because it identifies a medicine rather than a chemical, and correct wording of a product is as important as the active ingredient contained in it. From these considerations there are known more names for a drug, these being named after very different criterias. Drugs extracted from the medicinal plants that bear names similar to the plant or levurae of which are obtained (eg atropine (Atropa belladonna), strychnine (Strychnos Nux Vomica), caffeine (Coffea arabica), digitaline (Digitalis purpurea), penicillin (Penicillium notatum), streptomycin (Streptomyces griseus), etc.
Matches the chemical structure and is often very complicated, being a common factor for many names that may have made a drug (eg phenyl-ethyl-barbituric acid is the chemical name of barbiturate derivative known in more than 120 names).
Is the name mentioned in the Pharmacopoeia for a drug and is expressed in Latin (eg sodium et benzoas for Caffeine sodic benzoate). It is used more by scholars and by those who are active in the preclinical stage. A range of products bear names that indicate the action or field of use, eg Anesthesine, Algocalmin, Rumisan, Cardiazol, Oxiuran, Vetranquil, Enteroguard, Pneumoguard etc. But there is a huge number of names for the same substance or the same preparation, set by the producing company, can remember the name part of the chemical structure (eg, aspirin has over 90 names, vitamin A, more than 100, antibiotics, tranquilizers, hormones, vitamins, to each substance about 70-100 names).
Since advertising is made under the drug's brand name, most clinicians recommend the product under this name. To put order in the nomenclature of drugs, World Health Organization (WHO) through its specialized committees established for each substance an International Common Name (ICN) or Denomination Commune Internationale (DCI), based on chemical structure or other criteria, easy to remember of the substance (eg aminophenazonum for pyramidon, methenaminum for urothropin, pethidinum for myalgin, etc).
To internationalize the drug names, in the scientific literature, besides the commercial name to mention also the international common name (ICN), usually in Latin (returning to the previous example: phenyl-ethyl-barbituric acid = phenobarbitalum). This „equalization” which started locally it is now coordinated nationally and even internationally. Requirements and recommendations resulting from it are published in reference works known as Pharmacopoeias or Drug Codexes.
Evolution and sub-branches of Pharmacology
Pharmacology as science has developed greatly in the recent decades and has now many sub-branches of these include:
Pharmacognosy (pharmakon = medicine, gnosis = knowledge),
who deals with the knowledge that drugs are extracted from medicinal substances, indicating their main features and properties. Pharmacognosy classified after the origin of medicinal substances can be: plant, animal and mineral.
Studies synthesis and chemical structure of the active drug substances and their physicochemical properties. Progress in this branch have allowed the development of biopharmacy as sub-branch.
Pharmacodynamics (dynamis = force, action)
Is the part of pharmacology that deals with drugs' action in the body and its response to the contact with the drug substance, formulation and routes by which drugs act.
Studies drugs' effect on laboratory animals or on isolated organs and systems, with didactic and research purpose.
Tracks clinic eefect od the drugs during administration in animals or humans.
Pharmacokinetics (kinetikos = moving)
is the branch of pharmacology that deals with the drugs fate in the body, relation between dose and temporal changes that can occur at drug concentrations in different areas of the body as well as the mathematical models. The effects of pharmacological research, temporal and intensity kinetic effects play an important role in pharmacology science. These two parameters are functions of concentration dynamics in different compartments of the body.
Pharmacokinetics sub-branches are the: invasion phase (absorption and distribution of drugs after their accomplished optimal concentrations which are made to obtain pharmacodynamic effect) and evasion or elusive phase (drug metabolism and elimination stages).
Is studying the ways to measure intensity of drugs' effects, pharmacodynamics and pharmacokinetics together, enabling the correlation between dose intensity and effect of used medicines. Many of the accumulated knowledge of pharmacodynamics, pharmacokinetics came to us from experiments performed on lab animals. Studies of pharmacodynamics and pharmacokinetics are repeated than on healthy and sick pets, in order to specify as fair the use of remedies. Based on experiments on laboratory animals and methods of measurement, it can be established the therapeutic value of a substance for humans.
Isolation and cultivation of organisms responsible for the installation of infectious diseases have made rational basis for the chemotherapeutic agents testing. Identifying the nature of dysfunction in diseased organs suggested the reasoning for the use of those drugs that modiffied the functional capacity of those organs. Development of chemical industry led to a rapid growth of the potential medicines available for testing.
Pharmacotherapy (therapoeia = care) or clinical pharmacology
Studies the clinical application of drugs in various diseases, insisting on the mechanism of action, therapeutic efficacy, side effects, potential toxicity.
This branch includes also the:
- basic clinical pharmacology, which aims to obtain general information about the healthy animal and
- applied clinical pharmacology, investigating the drug's effect on disease status.
Veterinary Clinical Pharmacology
Is the study of medicines effect in animals patients. This works at the interface between medicine and pharmacology to pharmacological principles' integration with veterinary medicine. A controlled evaluation of safety and efficacy of drug therapy in animal patients is a major concern of veterinary clinical pharmacology.
Includes all those means and non-medication treatments (physical agents, diet, etc) to ensure health in suffering humans and animals.
Is a branch of pharmacology that deals with drugs that selectively inhibit or destroy specific disease agents such as bacteria, viruses, fungi and parasites. Use of this speciffic term was extended also to the use of speciffic drugs to treat neoplastic diseases. Chemotherapeutic drugs affects mainly the pathogenicity of abnormal cells than the normal host cells.
Deals with prescription and preparation of medicinal forms.
It comprises two branches:
- Pharmacography (graphein = write), who study the form of recipes prescription drugs (or Prescribing).
- Pharmaceutic techniques (or galenics) studying medicinal preparation forms. This sub-branch has become almost completely preserve of pharmaceutical industry, becoming a separate study discipline.
Is a pharmacology branch of study dealing with acute or chronic intoxication and adverse effects of medicinal products. It follows the installation conditions of these effects, externalizing and its intensity.
Establishes correlations between drug's components and intracellular biochemical compounds' activity.
is a newer branch of pharmacology, that studies the influence of drugs on genetic factors. Being knowed the correlation between enzyme activity and genome, any genetic variation in the plan may involve a different sensitivity to certain drugs.
Extended pharmacological research in the field, led to the emergence of new sub-branches of pharmacology like:
- biochemo-morphology, etc.
Of a particular interest, is biopharmacy branch, which deals with the study of relationships between physicochemical properties of drug substances, as conditioning and administration, its pharmacokinetic parameters and its obtained bio-pharmacological effects.
Is a concept introduced in the 80s, underlying bio-pharmacy, which refers to how substances are releasing from the drug formulation, issue which conditioning therapeutic substances'' absorption and diffusion in the body. Today's veterinary pharmacology contains great information from all the medicines' science and, like the ancient predecessor: De materia medica, is a compositum.
Due to its base content, and pharmacology's applied field is able to link the actual practice, between the preclinical and clinical studies in veterinary medicine.
In this context it is to note, that toxicology differs from pharmacology only in that the to toxins, by definition, produce undesirable effects on living organisms. Because many drugs may produce both favorable and unfavorable responses, it is clear that there is an overlap of interests and study techniques in toxicology and pharmacology in developing remedies.
Pharmacology was not solely responsible for the vast development that took place in rational therapy this century. In fact, pharmacology was largely based on other disciplines for experimental techniques and develop other areas of paved road of progress in therapy. A very strict separation of science related to pharmacology, it is not possible. Also, pharmacology can not be characterized strictly in terms of experimental methodology used.
Modern experimental pharmacology have had taken a very large number of methods from the same group of basic sciences (eg physiology, biochemistry, radiochemistry, biophysics, endocrinology, microbiology, immunology, histology etc.), without having or claiming a specific pharmacological methodology.
Between principles and methodologies used in the pharmacological and toxicological research, there is no absolute differentiation. Instead, there is a continuous and beneficial intermingling between these two areas. Once it is discovered or synthesized a new substance, which could present a potential interest in medical terms, the Descriptive pharmacology is the first to enter in the „role” (it researches and sets the descriptive terms, the activity of the studied substance). Simultaneously, descriptive toxicology determine the toxicity symptoms induced. The next step is pharmacological and toxicological research, the question arises at this point is: Why a substance shows a certain effect and some toxicity?
This stage of the research lead to understanding the mechanism of drug action. This step, along with descriptive pharmacology, are called as Pharmacodynamics.
Of those shown so far is clear that, in general, is difficult to fully explain the drugs' mechanism of action. Methods and knowledge of physiology, pathophysiology, biochemistry, biophysics, microbiology, etc. are essential to perceive the processes that take place at the cellular or subcellular level.
Switching from natural products, to the substances with known molecular identity, made possible the development of theories about how drugs actioning at the molecular level. Simultaneously, it has become possible the treatment of defficient status due of knowledge development about the essential elements and hormones. The latest example of how the medical profession benefit from the development of other branches, is the application of recombinant DNA technology in mammalian peptide hormone synthesis by genetically modified bacterial cultures (eg human insulin, bovine growth hormone). In this case pharmacology has gained from new biotechnologies.
A typical example from veterinary medicine, is the use of antibiotic growth promoters. These drugs, were discovered empirically, then being used for any reasonable application in the treatment of bacterial infections, now used also, more or less correct, in meat animals reared intensively.
Pharmacopoeia (pharmacon = remedy, poise = to do) is the base Handbook of medicinal forms preparation. It is the official code of rules for preparation and control of officinal deug forms, of the raw materials purity standards, medicines' conservation etc., having character of law.
Pharmacopoeia monographs include simple inorganic or organic medicinal chemicals, vegetal and animal products, the preparation of pharmaceutical forms and of galenic ones (officinal). The order is in alphabetical sequence, monographs title is in Latin and Romanian, in some situations as the most popular data and synonyms. After the description of pharmacopoeia monographs, are presented the specific methods of analysis and the necessary tables usual for the pharmaceutical practice.
Pharmacopoeia requirements are mandatory for all units that produce, control, store and distribute medicines.
For the organic substances, it was adopted the Common International Denomination = Denomination Commune Internationale (DCI) indicated by the World Health Organization (WHO). For the inorganic substances, to the Latin name is indicated cation and then anion, to all substances with known structure being described also the chemical formula (for the organic ones both the gross and the structural formula). The atomic and molecular mass (including water of crystallization) is expressed in decimals. Each monograph contains: description of main properties (smell, taste, solubility, physical and chemical), methods of identification, purity conditions, specific assay methods, storage conditions and in some active substances case, the maximum doses of substances.
In the case of vegetal products' monographs, plant's name precedes the used part (eg Ipecca, Ipecacuanhae radix = root), after the title being specified which part of the plant, have a role in therapy, mode of drying, the degree of crushing, content in active substances and a paragraph „Description” which includes macro and microscopic characters of the product, the other aspects being same as the chemical monographs. Monographs that refer to pharmaceutical forms after definition describe methods of preparation, permissible variations of weight, quantitative methods, conservation way. Officinal medicinal forms monographs, include extra data on the composition of the preparation, preparation, reactions, identification and purity conditions.
In the Pharmacopoeia are presented also details of the measuring units, the significance of some expressions related to temperature, solutions, solvents, etc., data about the shelf life, the list of active and toxic substances.
Short historic and evolutions
Pharmacopoeia first record was dated at 2100 BC in Sumerian (Pharmacopoeia of Nippur, written on baked clay).
First Pharmacopoeia appeared in Asia was Japan, around the year 900, which describes 1025 products from Chinese sources. In 1679, Japan Pharmacopoeia reached 70,000 pages being considered an encyclopedia of natural products.
First Arab Pharmacopoeia included over 200 medicinal plants, many used today.
First European National Pharmacopoeias, have appeared in the late eighteenth century and early nineteenth century in: the Swiss Confederation (1775), Pharmacopoeia Batavia (in Netherlands, 1805), France 1818, Italy (Turin, Sardinia, Sienna, Venice, Parma, Florence, Ferrara, 1840-1882), UK (1864) etc.
First International Congress of Pharmacology held in 1865, where ittered for the first time the need of an united Pharmacopoeia. After two failures in 1939, and respectively in 1946, appeared finally in 1952, Pharmacopeea Internationalis a monumental work. The work was written in English, French and subsequently in Spanish.
In the period 1968-1971 (completed with annual supplements) appeared the Pharmacopoeia of the Common Market (after a 10 years activity in The European Commission). These Pharmacopoeia serve as a basis to standardize the various rules of the national pharmacopoeias.
First appeared in 1862, under governance of Prince Alexander Cuza, and under the care of scholar pharmacist Constantine C. Hepites, being one of the first works of its kind in Eastern Europe. From 1862 until 1993, appeared ten editions of the Romanian Pharmacopoeia, (the XI Edition is in progress).
First appeared in 1977 and it was published in Britain following the publication in 1953, 1965 and 1970 British Veterinary Codex, to which were added and quality control standards of British Pharmacopoeia from 1972. Pharmacopoeia (Veterinary) British is published every five years and the responsibility lies with Britain's Medical Commission. Pharmacological science, in real the modern sense, was asserted about a half century, but the use of means of healing dates back to antiquity. In the art of healing, for centuries, have won two currents, being generally available today. These are of the allopathy and homeopathy:
The principle of allopathy (allos = opposite, pathos = disease)
Has been introduced since the famous ancient physician Hippocrates of Cos. Allopathic treatment is a system based on the principle: Contraria contrariis curentur, where drugs are used to produce opposite effects to disease symptoms. Most drugs used in veterinary medicine today are allopathic substances.
The principle of homeopathy (homoios = similar, pathos = disease)
Was set much later, in late eighteenth century, by the Saxon physician Samuel Hahnemann (1755-1843)(as a curiosity, he has worked as a librarian at a time of Bruckenthal Palace Sibiu, RO). Homeopathy is based on the principle: Similia similibus curentur, a syndrome or disease being treated with substances that produce similar effects. He is the exact opposite to allopathy and is based on three principles:
- the principle of similarity,
- the infinitesimal doses principle (very high dilutions),
- the tratment's individualization principle.