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pharmacology
Medical Science Seminar
Mrs Leonardi
What is a drug?
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“A substance used as a medicine for
the treatment of disease.”
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“A chemical agent that is used in
treatment, cure, prevention, and diagnosis of a disease.”
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However, many other substances can be classified as
drugs, even though they are not commonly associated
with disease (caffeine, nicotine, alcohol, cocaine, heroin,
etc.).
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“Any chemical agent other than food that affects living
organisms by altering physiological processes.”
What is
Pharmacology?
The science of drugs (From the Greek words: pharmakos, medicine
or drug; and logos, study).
“The science that deals with the study of the mechanism of action,
uses, adverse effects and fate of drugs in animals and humans”
“Pharmacology is concerned with the changes in
function, structure and chemical properties of the body
brought about by chemical substances”
Sir W. Patton (1986)
What do pharmacologists study?
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the mechanisms responsible for drug tolerance and
addiction.
the molecular targets for drugs and how they
produce their effects.
the mechanisms responsible for drug-resistance
in cancer cells, microorganisms and parasites.
how drugs can be used to prevent conditions such
as cancer, heart disease and neurodegeneration.
how the body terminates the action of a drug.
the toxic effects of herbicides and pesticides.
the effect of chemical agents on subcellular
mechanisms.
the use of drugs as tools to investigate
cellular function
and many other things.
Pharmacology: Its subdivisions
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Pharmacotherapeutics- the study of the effects of chemical agents
of therapeutic or diagnostic value used in prevention, cure,
diagnosis or treatment of disease.
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Toxicology- the study of the effects of chemical agents with
potential for toxicity on biological systems.
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The study of pharmacotherapeutics and toxicology includes two
closely associated areas: pharmacodynamics and
pharmacokinetics.
Pharmacodynamics--What a drug does to
the body.
Pharmacodynamics is the study of the molecular, biochemical, and
physiological effects of drugs on cellular systems and their
mechanisms of action. Simply put: What a drug does to the body;
Receptor interactions, dose/response and mechanisms of
therapeutic and toxic action.
Response vs Time
When you study pharmacodynamics you
study: Effects produced by the drug
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Depressing- anesthetics used in surgical
procedures
Stimulating-amphetamines used in the treatment
of narcolepsy
Destroying-aspirin used to destroy prostaglandin
synthetase thus preventing inflammation
Replacing-growth hormone used to treat
children of short stature
When you study pharmacodynamics you
study: Mechanism of Action
Example: nicotinic acetylcholine
Mechanism of Action of Chantix
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Bound nicotinic
acetylcholine receptors
are associated with
excitation of neurons.
Dopamine is produced
as a result of these
bound receptors.
Dopamine is associated
with the pleasure center
of the brain.
Nicotine competitively
binds these receptors.
Mechanism of Action of Chantix
When you study pharmacodynamics you
study: Sites of action of the drug
“Anesthesia awareness”
EEG monitors cerebral cortex
Local (could be topical), Regional (ex.
epidural), and General anesthetics (can
not be aroused by pain)
When you study pharmacodynamics you
study: Dose /Effect relationship
Half maximal effective
concentration (EC50)
refers to the
concentration of a drug
which induces a
response halfway
between the baseline
and maximum.
When you study pharmacodynamics
you study: Safety of the drug
Pesticide usage
Pesticides
1973
1947
Pharmacokinetics--What the body does
to a drug.
Pharmacokinetics deals with ADME -the absorption, distribution,
metabolism and excretion of drugs. Simply put: What the body does
to a drug. (rate quantification brings mathematical component
ADME
Absorption
Distribution
Metabolism
Elimination
Caffeine is a psychoactive stimulant
Absorption and Distribution- Caffeine is
completely absorbed by the stomach and
small intestine within 45 minutes of ingestion
In
healthy adults,
caffeine's half-life is
approximately 3–4
hours and in infants
and young children,
the half-life may be
longer than in adults;
half-life in a newborn
baby may be as long
as 30 hours.
Metabolism- Caffeine
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Caffeine is metabolized in the liver into three
primary metabolites: paraxanthine (84%),
theobromine (12%), and theophylline (4%)
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Pharmacodynamics of metabolized caffeine
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Paraxanthine (84%): Has the effect of increasing lipolysis,
leading to elevated glycerol and free fatty acid levels in the blood
plasma.
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Theobromine (12%): Dilates blood vessels and increases urine
volume. Theobromine is also the principal alkaloid in cocoa, and
therefore chocolate.
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Theophylline (4%): Relaxes smooth muslescof the bronchi, and
is used to treat asthma. The therapeutic dose of theophylline,
however, is many times greater than the levels attained from
caffeine metabolism.
Elimination- Caffeine
Caffeine is metabolized in the liver and eliminated in the urine.
Another example:
Orlistat is a reversible inhibitor of lipases.
 Also known as Alli.
 Binds the lipase and renders it inactive.
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Pharmacotherapeutics the study of the effects of
chemical agents of therapeutic or diagnostic value used in prevention,
cure, diagnosis or treatment of disease. You must study their
pharmacodynamics and pharmacokinetics.
StudentConsult (on 21 December 2005 05:34 PM) © 2005 Elsevier
Toxicology- the study of the effects of
chemical agents with potential for toxicity
on biological systems.
•Toxicology is the study of the adverse effects of chemicals
on living organisms. It is the study of symptoms,
mechanisms, treatments and detection of poisoning
•Toxicology studies the relationship between
dose and its effects on the living organism.
The chief criterion regarding the toxicity of a
chemical is the dose, the amount of
exposure to the substance.
•You must study the pharmacodynamics
and the pharmacokinetics of the chemical.
History of Toxicology
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Paracelsus, (1493-1541), the father of modern
toxicology, said “All things are poison and nothing is
without poison; Only dose makes the poison”.
Paracelsus was the first person to explain the doseresponse relationship of toxic substances.
Discoveries were being made in toxicology throughout
the 1700s and 1800s.
www.toxipedia.org
Even a benign substance like water can cause harm in
excessive amounts.
Dose-Response-Pharmacodynamics
The Hormetic Dose-Response Curve
PHARMACY
Often confused with
pharmacology, pharmacy is
a separate discipline in the
health sciences. It is the
profession responsible for
the preparation, dispensing,
and appropriate use of
medication, and provides
services to achieve optimal
therapeutic outcomes.
History of Pharmacology
Ancient times
 Shamanism / ethnobotany
 Primitive humans identified edible and poisonous plants and
animals that were used for appetite suppressants, stimulants and
psychedelics.
 Physicians used extracts from plants and animals as therapeutic
agents.
 Opium has been in use for at least 5000 years.
 Cocaine (not in pure form) for 2000 years, appetite suppressant.
Egypt and Babylonia
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1600 B.C. : papyrus listing and characterizing 700 diseases.
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The Egyptians used to develop remedies for disease, sources, nature and
preparation of drugs.
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They transmitted the foundations of medicine to India and Greece.
India
 Sushruta (500 B.C.) Hindu physician:
1st aseptic surgery, 1st skin graft, 1st vaccination against a disease
similar to smallpox.
 He described 1100 diseases.
 All this unknown in Europe for 2000 years.
Claudius Galen (129-200A.D.)
 Both theory and practical experience contributed to pharmacology.
Paracelsus (1493-1541)
 United chemistry with medicine; discarded theories of the causes of
disease; advocated that illness is a derangement of body chemistry to be
treated by simple chemical therapeutic agents.
William Harvey (1578-1657)
 Explained circulation of blood; this discovery signaled the beginning of
study in medical sciences.
Johann Jakob Wepfer (1620-1695)
 Used animal experimentation to study pharmacology.
Claude Bernard (1813- 1878)
 First to demonstrate and explain how a drug produces its action in the body
Oswald Schmiedeberg (1838-1921)
 Founded the first journal of pharmacology.
Paul Elrich (1854-1915)
 Ushered in era of chemotherapy, formulated concept of receptors ( part of
chemical components of living tissue with which a drug combines to
produce effects)
John Jacob Abel (1857-1938)
 Father of American Pharmacology; First full time professor of pharmacology
• ADDITIONAL SLIDES
Distribution and Elimination
Pharmacokinetics Chantix
(varenicline)
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Absorption/Distribution
Maximum plasma concentrations of varenicline occur
typically within 3-4 hours after oral administration.
Following administration of multiple oral doses of
varenicline, steady-state conditions were reached within
4 days.
Metabolism/Elimination
The elimination half-life of varenicline is approximately
24 hours. Varenicline undergoes minimal metabolism
with 92% excreted unchanged in the urine.