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PHARMACOLOGY:
Introduction
Pharmacology
• Pharmacology (Greek word)
• Pharmakon logos
•
Drug Knowledge
Pharmacology is the science of drug
which deals with the detail study of
sources, chemical nature, route of
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administration, absorption,
pharmacological effect, metabolism,
excretion and side effects of the
drugs.
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• Pharmacology is the science that deals with the actions, mechanism of
action, uses, adverse effects and fate of drugs in animals and humans. The
word pharmacology comes from the ancient Greek word for drugs and
logos meaning discourse in. It is the study of what biologically active
chemical compounds (drugs) do in the body and how the body reacts to
them.
• It relates to other major bioscience disciplines such as physiology,
biochemistry, cellular and molecular biology, microbiology, immunology,
genetics, and pathology.
• Pharmacology is concerned with the effects of drugs on living systems or
their constituent components such as cells, cell membranes, cell organelles,
enzymes and even DNA.
• In brief Pharmacology is the study of biologic effects of drug
• Drugs are chemical agents that affect living process and are used in the
treatment, prevention or diagnosis of diseases or in the prevention of
pregnancy. As a rule drugs will only modify existing cell functions but will not
create new ones. Thus a certain cellular function may be stimulated (an
increase in function) or depressed (a decrease in function) by drugs.
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Drug
• The word “drug” is derived from the French word “drogue” means “a dry
herb”.
According to WHO:
• A drug is any substance or product that is used or intended to be used to
modify or explore physiological system and pathological state for the
benefit of the recipient. The benefit of the recipient (man or animal) is the
diagnosis, prevention, control or cure of the disease.
• For diagnosis: Barium sulfate…………
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• For treatment: Chloroquine in malaria.
• For prophylaxis: Pyrimethamine in malaria.
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Pharmacopoeia
• Pharmacopoeia (Greek word)
• Pharmakon poiein
Drug make
A pharmacopoeia is the official publication by the
pharmacopic mission of a country to maintain strict
uniformity of drugs in their official tests, preparation,
standard, dose, character, bio-assay, methods of
dispensing, their action and uses.
International pharmacopoeia is published by WHO. eg: BP, 15
USP, IP etc.
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Scope/branch of Pharmacology
• Pharmacodynamics: What drugs do to the body, ie: receptor interactions,
dose-response phenomena, and mechanisms of therapeutic and toxic
action. It includes pharmacological effects and M/A.
• Study of the molecular, biochemical, and physiological effects of drugs on
cellular / body systems and their mechanisms of action
• In brief it is the study and measurement of responses to drugs.
• Pharmacokinetics: What the body does to the drug, ie: it deals with the
study of absorption, distribution, biotransformation/metabolism and
excretion (ADME) of drugs and their metabolites in the intact organism. It
deals with the
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practical application of drugs in the treatment and prevention of disease.
In brief pharmacokinetics is the study of how the body absorbs,
distributes, metabolizes and excretes drugs.
• Pharmacotherapeutics: It is the study of clinical use of drugs to treat
diseases.
• Pharmacogenomics: The study of genetic influences on the
effectiveness and fate of drugs. It is the study of how genetics alters
responses to drugs. It deals with the study of genetically mediated
variations in drug response.
• Toxicology: The study of the adverse or toxic effects of
drugs and other chemical agents. 16
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• It is the study of poisonous effect of drugs and other chemicals ( household,
environmental pollutant, industrial, agricultural, homicidal) with the emphasis
on detection, prevention and treatment of poisonings. It is also includes the
adverse effects of drugs since the same substance can be a drug or a poison
depending on the dose.
Scope/branch of Pharmacology
• Biochemical Pharmacology: It describes the actions of drug on biochemical
processes within the cell.
• Clinical Pharmacology: It integrates therapeutics with the basic principles of
pharmacology, research methodology and biostatistics. It evaluates the
pharmacological actions of drug, preferred route of administration and safe
dosage range in human by clinical trials.
• Molecular Pharmacology: The action of drug at molecular level can be
described in molecular pharmacology.
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• Immunopharmacology: It deals with the immunological aspects of
drug action, including the effects of drugs in immune response and
development of antibiotics in response to drugs.
• Pharmacoepidemiology: It is the study of the effect of drugs on
populations.
• Pharmacoeconomics: it is the study of the cost-effectiveness of
drug treatments.
• What are the goals of Pharmacology?
To understand all aspects of drug action and efficacy –
to develop drugs/treatment regimes that have selective (beneficial)
actions without adverse effects (i.e. they don’t make things worse).
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Gene therapy
- It is the introduction of functional genetic
material DNA into target cells to replace
or supplement defective genes. It imparts
new function to cells.
Cancers
Alzheimer’s disease
Parkinson’s disease
Diabetes mellitus
Arterial Hypertension
Cystic fibrosis
Multiple sclerosis
Muscular dystrophy
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Passive (simple) diffusion
The lipid soluble unionized drug diffuse across
the lipid biomembrane in the direction of their
concentration gradient. It does not need energy.
Most drugs are week electrolytes. Their ionization
is pH dependent. The ionization of a week acid (AH)
is given by the equation of Henderson–Hasselbalch:
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[AH]
pKa = pH + log10 ------
[A-]
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pKa is the negative logarithm of acidic dissociation
constant of the week electrolyte. If the concentration
of unionized drug [AH] is equal to concentration of
ionized drug [A-], then
[AH]
--------- = 1
[A-]
since log 1 is 0, under this condition pH = pKa
In this case the molecules of drugs are 50% ionized.
For a week base:
[BH+]
pKb = pH + log10 ------
[B]
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