General Pharmacology

DEFINITIONS & BRANCHES OF PHARMACOLOGY

Pharmacology: It is an experimental science dealing with the properties of drugs
and their effects on living systems.
Pharmacognosy: It deals with the study of sources and identification (origin) of
drugs.
Pharmacodynamics: It refers to the study of response of an organism to the action
of drugs in absence of disease.
Pharmacokinetics: It is defined as the mathematical description of temporal changes in concentration of drugs and/ or their metabolites within the body.
Pharmacometrics: It deals with the study of qualitative and quantitative aspects of
drug effects in laboratory animals. It deals with measurement of drug responses.
Pharmacotherapy: It refers to use of drugs in treatment of diseases.
Therapeutics: It is a term describing treatment of disease in general and includes
use of drugs, surgery, radiation, behavioural modification and other modalities.
Clinical Pharmacology: Much of our knowledge of pharmacodynamics,
pharmacokinetics and pharmacometrics come from and continues to come from
experiments performed on healthy lab animals. The difficulty of transposing this
information with reliability into the realm of diseased domesticated patients gave rise
to clinical pharmacology.
In this, the appropriate pharmacodynamic, pharmacometric and
pharmacokinetic studies are repeated in healthy and diseased domesticated target
species with resultant gain in the precision of use of remedies.
Chemotherapy: It is a branch of pharmacology dealing with drugs that selectively
inhibit or destroy specific agents or disease such as bacteria, viruses, fungi and
other parasites.
Toxicology: Classically, it is defined as the study of poisons. It includes study of
toxicity or adverse effects of drugs or chemical, physical or biological agents in man
and animals.
It is a science that defines the limits of safety of chemical agents for
human and animal population.
Posology: It is the study of medicine dosage.
Dose: A dose is the quantity of medication to be administered at one time.
Dosage: It refers to determination and regulation of doses.
Loading dose: It is one or series of doses that may be given at the onset of therapy
with the aim of achieving the target concentration rapidly.
Maintenance dose: It is a series of relatively small doses that follow the loading dose
in order to maintain an effective concentration in the bio-phase.
Metrology: It is the study of weights and measures as applied to preparation and
administration of drugs.

Pharmacy: It is the art and science of compounding and dispensing drugs or
preparing suitable dosage forms for administration of drugs in man or animals. It
includes collection, identification, purification, isolation, synthesis, standardization
and quality control of medicinal substances. The large scale manufacture of drugs is
called Pharmaceutics. It is primarily a technological science.
Materia medica: It is an obsolete didactic (instructive) subject that was concerned
with pharmacy, posology, pharmacognosy and indications for therapeutic use of
drugs. This subject was purely descriptive in nature and has been replaced in the
modern veterinary medical curriculum by the science of comparative pharmacology.
Comparative pharmacology: It deals with the study of variation in drug effects in
different species of animals.
Neutraceuticals: These are nutritional products which allegedly have some
therapeutic value in addition to their scientifically recognized nutritional content.
Biotechnology: Originally, this was the production of drugs or other useful products
by biological means (e.g. antibiotic production from microorganisms or production of
monoclonal antibodies). Currently in the biomedical sphere, biotechnology refers
mainly to the use of recombinant DNA technology for a wide variety of purposes,
including the manufacture of therapeutic proteins, diagnostics, genotyping,
production of transgenic animals, etc. The many non-medical applications include
agriculture, forensics, environmental sciences, etc.
Pharmacogenetics: This is the study of genetic influences on responses to drugs.
Originally, pharmacogenetics focused on familial idiosyncratic drug reactions, where
affected individuals show an abnormal-usually adverse-response to a class of drug.
It now covers broader variations in drug response, where the genetic basis is more
complex.
Pharmacogenomics: This recent term overlaps with pharmacogenetics, describing
the use of genetic information to guide the choice of drug therapy on an individual
basis. The underlying principle is that differences between individuals in their
response to therapeutic drugs can be predicted from their genetic make-up.
Pharmacoepidemiology: This is the study of drug effects at the population level. It
is concerned with the variability of drug effects between individuals in a population,
and between populations.
Pharmacoeconomics: This branch of health economics aims to quantify in
economic terms the cost and benefit of drugs used therapeutically.
Nanotechnology: Nanotechnology is the study and use of structures between 1
nanometer (nm) and 100 nanometers in size. Nanotechnology is the study of
phenomena and fine-tuning of materials at atomic, molecular and macromolecular
scales, where properties differ significantly from those at a larger scale.
The applications of nanotechnology to pharmacology are biochips, nanosensors, bioreactors, neural stem cells, immune nanoparticles, biodegradable polymers, and convection-enhanced drug delivery in the diagnostics and treatment of diseases.

OTHER DEFINITIONS:
Drug:
A drug can be defined as a chemical substance of known structure, other than
a nutrient or an essential dietary ingredient, which when administered to a living
organism, produces a biological effect. Drugs may be synthetic chemicals, chemicals
obtained from plants or animals or products of genetic engineering.
According to WHO, “Drug is any substance or product other than food that is
used or intended to be used to modify or explore physiological systems or
pathological states for the benefit of the recipient”.
(To use the word ‘drug’ intending only a harmful, dangerous or addictive substance
is to abuse a respectable and useful word.)
Medicine: A medicine is a chemical preparation which usually but not necessarily
contains one or more drugs, administered with the intention of producing a
therapeutic effect. Medicines usually contain other substances (excipients,
stabilizers, solvents etc.) besides the active drug to make them more convenient to
use.
Over the counter drugs: These are those preparations that can be sold without any
restriction because they can be adequately labeled for layman use.
Prescription drugs: Drugs that can be used only on the order of a licensed
veterinarian/ physician/ dentist/ surgeon. They are also known as legend drugs.
Essential drugs: Drugs that satisfy the healthcare needs of majority of the
population. They should therefore be available at all times in adequate amounts and
in appropriate dosage forms.
Pro-drugs: Drugs that are inactive or have a low order of activity in the form
administered and are metabolized to the active form in the body.
Hard drugs: Drugs used for non-medical purposes that are liable to disable the
individual seriously as a functioning member of the society by inducing severe
psychological and/or physical dependence. Example – Heroin.
Soft drugs: Drugs used for non-medical purposes that are less dependence
producing. There may be psychological dependence but not physical dependence,
except with heavy dose. Example – Amphetamine.
Nootropic drugs: Drugs that affect the intellect. These drugs are claimed to enhance learning, increase brain resistance to stress including hypoxia and stimulate brain metabolism especially in senile patients. Example – Piracetam

Orphan drugs: Orphan drugs are drugs or biological products for diagnosis/
treatment/ prevention of a rare disease condition for which there is no reasonable
expectation that the cost of developing and marketing it will be recovered from sales
of that drug. Examples – Acetylcysteine. These drugs may be life saving for some
patients, but are not commercially available.
Empirical therapy: It is the use of certain agents that prove successful in a series of
cases of the same disease, although, it is not possible to explain their actions. Their
value has been demonstrated by experience.
Rational therapy: It is the term used with reference to the application of remedial
measures which can clearly explain the reasons for their application. Rational
therapy is based on a thorough knowledge of the normal physiology, changes in
physiology due to pathological conditions and the pharmacological basis for use of
the drug. This implies a precise diagnosis and knowledge of the etiology of affection,
so that we can act directly or indirectly on the causes which produce it and an
intimate knowledge of the actions of the drugs which we employ.
Curative therapy: It is the therapy aimed at bringing about a cure in the patient, like
the use of antimicrobials in a bacterial infection.
Prophylactic or preventive therapy: It is the therapy aimed at preventing the
occurrence of a disease, like the use of vaccines for preventing bacterial and viral
infections.
Symptomatic or palliative therapy: It aims at treating the condition based on the
symptoms and providing relief to the patient without actually spending time on finding
the cause of the disease, like the use of anti-convulsants in epilepsy.
Replacement therapy: It aims at replacing the constituents to the normal level when
there is a reduction in the level of the constituent due to some pathological condition,
like fluid and electrolyte replacement in dehydration.
Additive therapy: It is the therapy given to add on the existing level of the normal
constituent even though there may not be a reduction in the level of that constituent,
like the use of anabolic steroid to build up body mass.
Iatrogenic disease: It means physician caused disease i.e. disease consequent
upon following medical advice or intervention. Iatrogenic was first applied to disorder
induced in the patient by auto suggestion based on physical examination or manner
of examination or discussion by the doctor.

 

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