Download introductory lecture in pharmacology

INTRODUCTORY LECTURE
IN PHARMACOLOGY
Learning Resources
1. Textbooks:
1.Basic and Clinical Pharmacology by Bertram G.
Katzung, Mc Graw-Hill.
2. Lippincott’s Illustrated Reviews: Pharmacology,
Mary J Mycek, Richard A Harvey, Pamela C Champe
3. Goodman and Gillman’s Pharmacological Basis of
Therapeutics, Laurence Brunton, John Lazo, Keith
Parker.
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Cont’d
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e-Books
Journals
Course Objectives

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To establish a good grasp of concepts important to
the discipline of pharmacology.
To have a thorough understanding of
pharmacodynamics and pharmacokinetics.
What is Pharmacology?
Pharmacology: derived from 2 Greek words
- Pharmakon = drug
- Logos = word/discourse
i.e. the study of substances (drugs or chemicals) that
interact with living systems through chemical
processes, especially by binding to regulatory
molecules and activating or inhibiting normal body
processes.
Cont’d
Among chemical agents are:
 Hormones
 Neurotransmitters
 Growth factors
 Drugs
 Toxic agents in the environment
Cont’d

The medicinal/organic chemist may discover a new
chemical compound, but it is the pharmacologist
who is responsible for testing it for pharmacological
activity.
Cont’d

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A drug is a single chemical entity present in a
medicine, that is used for diagnosis, prevention and
treatment of diseases.
It brings about a change in the normal body
physiology through chemical interaction and does
not produce a new effect.
Cont’d

WHO (1966): “Drug is any substance or product
which is used to modify or explore physiological
system or pathological states for the benefit of the
recipient”.
Cont’d

A drug can be defined as a natural product,
chemical substance, or pharmaceutical preparation
intended for administration to a human or animal to
diagnose or treat a disease.
Cont’d

The word drug is derived from the French drogue ,
which originally meant dried herbs and was
applied to herbs in the marketplace used for
cooking rather than for any medicinal reason.
Cont’’d

Medication, and less frequently, medicament are
terms that are synonymous with the word drug.
Cont’d
Pharmacology studies drug’s:
- Origin
- History
- Dosage
- Pharmacokinetics
- Pharmacodynamics (action)
- Effect
- Side effects
- Adverse effects
Cont’d
-
Toxicity
Clinical uses
Contraindications
Cont’d

Pharmacology is a unique combination of the
biomedical and clinical sciences, and it serves as a
link between the two broad areas.
Cont’d
There are two main branches of Pharmacology:
 Pharmacokinetics-what the body does to the drugs.
It studies the fate of drugs once ingested and the
variability of drug response in varying patient population.
It includes: drug absorption
drug distribution
drug metabolism
drug excretion

Cont’d
Pharmacodynamics-what drugs do to the body.
It studies the mechanism by which drugs act.
Also studies endogenous agents.

Cont’d
Drug Dose Administration;
Disintegration of Drug.
* Pharmacokinetics: Absorption/Distribution
Metabolism/Excretion.
* Pharmacodynamics: Drug Receptor Interaction.
* Pharmacotherapeutics: Drug Effect or Response.

Pharmaceutical:
Subdivisions of Pharmacology
Pharmacotherapeutics: Use of drugs for prevention
and cure of diseases.
 Pharmacy: is the science and profession concerned with
the preparation, storage, dispensing, and proper use of
drug products. Related sciences include pharmacognosy,
medicinal chemistry, and pharmaceutical chemistry.
 Pharmacognosy is the study of drugs isolated from
natural sources, including plants, microbes, animal
tissues, and
-
Cont’d
minerals.
Medicinal chemistry is a branch of organic chemistry
that specializes in the design and chemical synthesis
of drugs.
 Pharmaceutical chemistry , or pharmaceutics , is
concerned with the chemical properties and
formulation of pharmaceutical products, such as
tablets, liquid solutions and suspensions, and aerosols.
Relationship between P’kinetics &
P’dynamics,
Cont’d

Chemotherapy: the branch of therapeutics, which is
concerned with the effects of drugs on
microorganisms and parasites as well as on
malignancies.
Cont’d

Toxicology: the science of poisons, which includes
detection and measurement of poisons as well as
treatment of poisoning.
Cont’d
-
-
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Neuropharmacology: study of the effect of drug
components on the nervous system
Molecular Pharmacology: study of the biochemical
and biophysical characters of drug molecules
Clinical Pharmacology: study of drugs in the
humans
Cont’d
- Posology: how medicines are dosed or calculation
of dose
- Pharmacogenomics: It describes the use of genetic
information to guide the choice of drug therapy on
an individual basis. It’s in essence a branch of
pharmacogenetics.
Cont’d
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
Pharmacogenetics: Study of drugs and their
interaction with genetic molecule.
Pharmacoepidemiology: 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.
Cont’d
-
-
Pharmacoeconomics: Quantifies in economic terms
the cost and benefit of drugs used therapeutically.
Immunopharmacology: The area of Pharmacology
that relates the response of the immune systems of
the body to drugs.
Cont’d
-
Systemic Pharmacology: How drugs affect the
various body systems e.g. CVS, Renal, Respiratory,
GIT.
Sources of Drugs

Drugs are obtained mainly from plants, animals,
microbes and mineral sources, but a majority of
them that are used therapeutically are from
synthetic or semi-synthetic products.
From Plants
The pharmacologically active components
in vegetable drugs are:
 Alkaloids: are basic substances containing cyclic
nitrogen. The important alkaloids are obtained
from:
• Opium (Papaver somniferum): Morphine group.
• Cinchona (Cinchona officinalis): Quinine
etc.

Cont’d
Belladonna (Atropa belladonna): Atropine
group.
• Pilocarpus sp.: Pilocarpine.
• Vinca (Vinca rosea): Vincristine, vinblastine.
• Rauwolfia serpentina (root): Reserpine.
• Coca (Erythroxylum coca): Cocaine.
Cont’d
Glycosides are ether like organic structure
combined with sugars, the non-sugar component
called aglycone or genin. The important glycosides
are:
• Digitalis (Digitalis purpurea, Digitalis lanata): Digoxin
etc.
• Stropanthus (Stropanthus kombe): Stropanthin etc.
• Senna (Cassia acutifolia): Sennoside etc.

Cont’d
Oils
 a. Fixed oils are glycerides of oleic, palmitic and
stearic acids. Mostly fixed oils are edible and used
for cooking. The fixed oils used as drug are:
• Castor (Ricinus communis): Castor oil.
• Olive (Olea europaea): Olive oil.
• Cocoa butter (Theobroma cacao):

Cont’d
Theobroma oil used as emollient in skin cream and
making suppositories.
• Cod liver oil and shark liver oil: Rich source of
vitamins A and D.
 b. Volatile oil or essential oil contains the
hydrocarbon terpene. The important volatile oils
are:
Cont’d
• Turpentine oil, from species of pines, used as a
counterirritant.
• Lemon oil (from Citrus limon), used as flavouring
agent.
• Peppermint, cardamom and fennel used as
carminative and flavouring agent.
Oil of clove is mainly useful in relieving pain in
toothache.
Cont’d
Resins are produced by oxidation and
polymerization of volatile oils. The different types
of resins are:
• Oleoresins: Male fern extract used for tapeworm
infestation.
• Gum resins: Asafoetida, used as carminative and
antispasmodic.
• Oleo gum resin: Myrrh, it has a local stimulant and
antiseptic properties and generally used in
mouthwash.

Cont’d
Balsams: Benzoin, used internally as expectorant and
externally as astringent.
• Balsam Tolu, used as stimulating expectorant.
Cont’d
Gums are the secretory products of plants. On
hydrolysis they yield simple sugar like
polysaccharides. They are pharmacologically inert
substances and mainly employed as suspending
and emulsifying agent in various pharmaceutical
products. The widely used preparations are gum
acacia and tragacanth.

Cont’d
Tannins are nonnitrogenous constituents of plant.
Chemically they are phenolic derivatives and are
characterized by their astringent action. Tannins are
generally employed in the treatment of diarrhoea
and burns. The important plants which contains tannins
are: Amla, Behera, Hirda (in combination
form ‘Triphala’), Black catechu and Ashoka bark.

Animal Sources
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Drug
Category
Insulin
Hormone
Thyroid extract Hormone
Shark liver oil Vitamin A
Animal source
Pancreas of beef or pig
Thyroid gland
Livers of shark and allied
species
Cod liver oil Vitamin A and D
Livers of Gadus species
Antisnake venom Immune serum Blood of horse
Hyaluronidase Enzyme
Testis of bull
Pepsin
Enzyme
Stomach of beef and
pig
Cont’d
Humans: There are certain products which are
obtained from human being e.g.
• Immunoglobulins: From blood.
• Placental extract: From placenta.
• Chorionic gonadotropin: From urine of pregnant
women.
• Growth hormone: From pituitary gland.

Cont’d
From Microorganisms: The different classes of
drugs obtained/ isolated from microbes are:
• Penicillin: Penicillium chrysogenum and notatum
(Fungus).
• Streptomycin: Streptomyces griseus (Actino-mycetes).
• Erythromycin: Streptomyces erythreus (Actinomycetes).

Cont’d
• Chloramphenicol: Streptomyces venezuelae
(Actinomycetes).
• Tetracyclines: Streptomyces aureofaciens and rimosus
(Actinomycetes).
• Polymyxin B: Bacillus polymyxa.
• Bacitracin: Bacillus subtilis.
• Nystatin: Streptomyces nouresi.
Cont’d
• Griseofulvin: Penicillium griseofulvum.
Apart from various other antibiotics obtained from
microorganisms, there are other products that are also
produced by microorganisms.

Cont’d
They are:
• Streptokinase, an enzyme from gram positive cocci
(Streptococcus pyogenes).
• Vitamin B12 (cyanocobalamin): Streptomyces griseus.
Cont’d
E. Synthetic
Paracetamol
F. Semi-synthetic
Ampicillin
G. Minerals
Magnesium Sulphate
Sodium Chloride
Magnesium trisillicate.
Cont’d
Synthetic Drugs:
Modern chemistry in the 19th century enabled
scientists to synthesize new compounds and to modify
naturally occurring drugs. Aspirin, barbiturates, and
local anesthetics (e.g., procaine) were among the first
drugs to be synthesized in the laboratory.

Cont’d
Semisynthetic derivatives of naturally occurring
compounds have led to new drugs with different
properties, such as the morphine derivative
oxycodone.
Cont’d


Genetic Engineering: human insulin, growth hormone
genes.
Hybridoma techniques: monoclonal antibodies.
Drug Preparations

Drug preparations include crude drug preparations
obtained from natural sources, pure drug
compounds isolated from natural sources or
synthesized in the laboratory, and pharmaceutical
preparations of drugs intended for administration
to patients.
Csrude Drug Preparation


Crude Drug Preparations
Some crude drug preparations are made by drying
or pulverizing a plant or animal tissue. Others are
made by extracting substances from a natural
product with the aid of hot water or a solvent such
as alcohol.
Cont’d

Familiar examples of crude drug preparations are
coffee and tea, made from distillates of the beans
and leaves of Coffea arabica and Camellia sinensis
plants, and opium, which is the dried juice of the
unripe poppy capsule of the plant, Papaver
somniferum .
Cont’d
Pure Drug Compounds
Pure Drug Compounds
It is difficult to identify and quantify the
pharmacologic effects of crude drug preparations
because these products contain multiple ingredients,
the amounts of which may vary from batch to batch.
Hence, the development of methods to isolate pure
drug compounds from natural sources was an
important step in the growth of pharmacology and
rational therapeutics.

Cont’d

Frederick Sertürner, a German apothecary,
isolated the first pure drug from a natural source,
when he extracted a potent analgesic agent from
opium in 1804 and named it morphine , from
Morpheus, the Greek god of dreams. The
subsequent isolation of many other drugs from
natural sources provided pharmacologists with a
number of pure compounds for study and
characterization.
Cont’d

One of the greatest medical achievements of the
early 20th century was the isolation of insulin from
the pancreas. This achievement by Frederick Banting
and Charles Best led to the development of insulin
preparations for treating diabetes mellitus .
Pharmaceutical Preparations


Pharmaceutical preparations or dosage forms are
drug products suitable for administration of a
specific dose of a drug to a patient by a particular
route of administration.
Most of these preparations are made from pure
drug compounds, but a few are made from crude
drug preparations and sold as herbal remedies.
Cont’d
TABLETS AND CAPSULES. Tablets and capsules are
the most common preparations for oral
administration because they are suitable for mass
production, are stable and convenient to use, and
can be formulated to release the drug immediately
after ingestion or to release it over a period of
hours.

Cont’d

A tablet must disintegrate after it is ingested, and
then the drug must dissolve in gastrointestinal fluids
before it can be absorbed into the circulation.
Variations in the rate and extent of tablet
disintegration and drug dissolution can give rise to
differences in the oral bioavailability of drugs from
different tablet formulations.
Cont’d

Tablets may have various types of coatings. Enteric
coatings consist of polymers that will not
disintegrate in gastric acid but will break down in
the more basic pH of the intestines. Enteric coatings
are used to protect drugs that would otherwise be
destroyed by gastric acid and are also to slow the
release and absorption of a drug when a large
dose is given at one time, for example, in the
formulation of the antidepressant, fluoxetine.
Cont’d

Sustained-release products , or extended-release
products, release the drug from the preparation
over many hours.
Cont’d

Capsules are hard or soft gelatin shells enclosing a
powdered or liquid medication. Hard capsules are
used to enclose powdered drugs, whereas soft
capsules enclose a drug in solution. The gelatin shell
quickly dissolves in gastrointestinal fluids to release
the drug for absorption into the circulation.
Cont’d

SOLUTIONS AND SUSPENSIONS. Drug solutions
and particle suspensions, the most common liquid
pharmaceutical preparations, can be formulated for
oral, parenteral, or other routes of administration.
Solutions and suspensions provide a convenient
method for administering drugs to pediatric and
other patients who cannot easily swallow pills or
tablets.
Cont’d
They are less convenient than solid dosage forms,
however, because the liquid must be measured each
time a dose is given.
Solutions and suspensions for oral administration are
often sweetened and flavored to increase
palatability.

Cont’d

Sweetened aqueous solutions are called syrups ,
whereas sweetened aqueous – alcoholic solutions
are known as elixirs. Alcohol is included in elixirs as
a solvent for drugs that are not sufficiently soluble
in water alone.
Cont’d
SKIN PATCHES. Transdermal skin patches are drug
preparations in which the drug is slowly released
from the patch for absorption through the skin into
the circulation. Most skin patches use a ratecontrolling membrane to regulate the diffusion of
the drug from the patch. Such devices are most
suitable for potent drugs, which are therefore
effective at relatively low dosages, and have
sufficient lipid solubility to enable skin penetration.

Cont’d

AEROSOLS. Aerosols are a type of drug
preparation administered by inhalation through the
nose or mouth. They are particularly useful for
treating respiratory disorders because they deliver
the drug directly to the site of action and may
thereby minimize the risk of systemic side effects.
Some aerosol devices contain the drug dispersed in
a pressurized gas and are designed to deliver a
precise dosage each time they are activated by the
patient.
Cont’d
OINTMENTS, CREAMS, LOTIONS, AND
SUPPOSITORIES.
Ointments and creams are semisolid preparations
intended for topical application of a drug to the skin or
mucous membranes. These products contain an active drug
that is incorporated into a vehicle (e.g., polyethylene
glycol or petrolatum), which enables the drug to adhere
to the tissue for a sufficient length of time to exert its
effect. Lotions are liquid preparations often formulated as
oil-in-water emulsions and are used to treat dermatologic
conditions.

Cont’d

Suppositories are products in which the drug is
incorporated into a solid base that melts or
dissolves at body temperature. Suppositories are
used for rectal , vaginal , or urethral administration
and may provide either localized or systemic drug
therapy.
Drug Nomenclature
1.
2.
3.
4.
Chemical Name: describes the chemical composition
and molecular structure e.g. Paraaminobenzenesulfonamide (sulfanilamide)
Code Name e.g. WR 180409 (empiroline), WR
142490 (mefloquine).
The code name is retained before an approved name
is coined.
Non-proprietary name: as listed in the Pharmacopeia
e.g. Sulfanilamide, phenothiazines, aminoglycosides,
paracetamol.
Proprietary or Trade name: coined by the
manufacturer e.g. panadol, septrin,
Sources of Drug Information
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United States Pharmacopeia (USP)
Physician’s desk reference (PDR)
British Pharmacopoeia
Pharmacopoeia Internationalis
British Pharmaceutical Codex
Canadian Formulary