This document provides an introduction to the field of pharmacology. It defines pharmacology as dealing with all aspects of drugs, including their sources, effects, side effects, metabolism, and elimination in the body. It then discusses key terms in pharmacology like pharmacokinetics, pharmacodynamics, and toxicology. The document also covers drug nomenclature, essential drug concepts, orphan drugs, factors governing drug administration routes, and special features of transdermal drug delivery systems. Finally, it discusses pharmacokinetic effects of drugs including absorption, distribution to tissues, metabolism, and excretion.

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Introduction to Pharmacology
By Prof. Dr. Shah Murad
shahmurad65@gmail.com

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♦ Pharmacology deals with all aspects of
drug/medicine/chemical
compounds,including their
source,effects,side
effects,permeability,distribution,metabolism
,mode of action, elimination/excretion in
the body.

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Drug/Medicine
♦ Chemical compound used for prevention,
diagnosis and cure of diseases

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♦Therapeutics term is used often for
cure of disease by drugs
♦ Therapeutic’s alternate term is used
“chemotherapy” but it is commonly
applied to cytotoxic/anti-tumor drugs

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General terms used in Pharmacology
♦ Pharmacokinetics
♦ Pharmacodynamics
♦ Pharmacotherapeutics
♦ Toxicology
♦ Pharmacy
♦ Posology
♦ Pharmaceutics
♦ Pharmacognosy
♦ Pharmacogenetics

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Drug nomenclature
♦ Chemical name
♦ Non-proprietary name (0fficial name)
♦ Proprietary(Brand) name

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Essential drug concept
♦ W.H.O has defined essential drugs as “those
chemical compounds that satisfy priority health
care needs of the population”

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Orphan drug
♦ Biological products for
diagnosis,treatment,prevention of a rare disease or
condition for which there is no reasonable
expectation that the cost of developing and
marketing it will be recovered from the sales of
that drug,e.g. sodium nitrate,potassium
sulfate,calcitonin,digoxin immune,liothyronine(T3)

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ORPHAN DRUG
♦ With a single diagnosed patient only,
ribose-5-phosphate isomerase deficiency
is presently considered the rarest genetic
disease.
♦ No single cutoff number has been agreed
upon for which a disease is considered rare.
A disease may be considered rare in one
part of the world, or in a particular group of
people, but still be common in another.

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Factors governing choice of route of drug administration
♦ Physical and chemical properties of the drug(solid/
liquid/gas;solubility,stability,pH)
♦ Site of desired action
♦ Rate and extent of absorption of the drug from
different routes
♦ Effect of digestive juices and first pass
metabolism on the drug
♦ Rapidity with which the response is desired
♦ Accuracy of dosage required
♦ Condition of the patient

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Special features of transdermal drug delivery system
♦ These are devices in form of adhesive
patches of various shapes and sizes,which
deliver the contained drug at a constant rate
into systemic circulation.
♦ The drug is held in a reservoir between an
occlusive backing film and a rate
controlling micropore membrane,the under
surface of which is smeared with an
adhesive impregnated with priming dose of
drug that is protected by another film to be
peeled off just before application.

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1st
Pharmacokinetic Effect of Drug
♦ It is transport of drug across biological
membranes.
♦ Drugs are transported across the membranes
by (a)Passive diffusion and filtration (b)
specialized transport.

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Influence of pH on passive diffusion
♦ Most drugs are weak electrolytes, i.e. their
ionization is pH dependent(contrast to strong
electrolytes---which are nearly completely
ionized at acidic as well as alkaline pH).
♦ Ions being lipid insoluble ,do not diffuse and
a pH difference across a membrane can
cause differential distribution of weakly
acidic and weakly basic drugs on the 2 sides.

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Fate of drug after its absorption
♦ It will bound to plasma protein……inactive form
♦ Free (unbound) form of drug will go to its site of
action or to storage tissue. It may excrete out in
unchanged form or 1st
it may be metabolized,then
excreted out by excretory organs.

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Pharmacokinetic difference
between formal tissues and brain
♦ Usual capillaries have large intercellular
pores through which even large lipid
insoluble molecules diffuse.
♦ Tight junctions in brain capillary and glial
cell processes/choroidal epithelium don’t
allow passage of non-lipid soluble
molecules/ions.

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Bioavailability,plasma concentration and therapeutic
concentration of drug
♦ Some drugs absorb slowly…exhibiting small
AUC and some have large AUC accordingly.

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Control release (CR) drugs
♦ Usually 30% of the dose of CR-drug outside
the semipermeable membrane is released
immediately.
♦ 70% of the dose is released slowly through
the membrane over the next 4-8 hours.

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