Introduction of Pharma

1. Introduction to
Pharmacology
Lecture by:
Pharmacist Sobia
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2. INTRODUCTION TO BASIC PRINCIPLES OF
PHARMACOLOGY
 Describe basic terminologies used in
pharmacology such as efficacy, potency,
therapeutic index, drug induced toxicity and
adverse effects.
 Describe the basic pharmacokinetic principles
such as absorption, distribution, metabolism
and elimination of drugs.
 Describe pharmaco-dynamics such as agonist,
antagonist and drug receptor interaction

3. PHARMACOLOGY
Pharmacology is the scientific study of the
effects of drugs and chemicals on living
organisms where a drug can be broadly
defined as any chemical substance, natural
or synthetic, which affects a biological
system.
Pharmacokinetics refers to what the body
does to a drug,
pharmacodynamics the drug does to the
body

5. Pharmacokinetics (ADME)
Absorption,
Distribution
Metabolism
Excretion
pharmacodynamics (the biochemical and
physical effects of drugs and the
mechanisms of drug actions)

6. Kinetics refers to movement.
Pharmacokinetics deals with a
drug’s actions as it moves through the body.
Therefore, pharmacokinetics discusses how
a drug is:
• absorbed (taken into the body)
• distributed (moved into various tissues)
• metabolized (changed into a form that
can be excreted)
• excreted (removed from the body)

7. Absorption
Drug absorption covers a drug’s progress
from the time it’s administered, through its
passage to the tissues, until it reaches
systemic circulation.
On a cellular level, drugs are absorbed by
several means—primarily through
active transport
passive transport.

8. First-pass effect
Drugs are transported to the liver before being
circulated to the rest of the body. The liver may
metabolize much of the drug before it enters the
circulation. This mechanism is referred to as the
first-pass effect. Liver metabolism
may inactivate the drug; if so, the first-pass effect
lowers the amount of active drug released into
the systemic circulation. Therefore, higher drug
dosages must be administered to achieve
the desired effect.

9. DISTRIBUTION
Drug distribution is the process by which the drug is delivered
from the systemic circulation to body tissues and fluids. Distribution
of an absorbed drug within the body depends on several factors:
• blood flow
• solubility
• protein binding.
After a drug has reached the bloodstream, its distribution in the
body depends on blood flow. The drug is quickly distributed to
organs with a large supply of blood. These organs include the:
• heart
• liver
• kidneys.
Distribution to other internal organs, skin, fat, and muscle is
slower.

10. the ability of a drug to cross a cell membrane depends on
whether the drug is water or lipid (fat) soluble.
Lipid-soluble drugs easily cross through cell membranes;
water-soluble drugs can’t. Lipid-soluble drugs can also cross
the blood-brain barrier and enter the brain.

11. As a drug travels through the body, it comes in
contact with proteins such as the plasma
protein albumin. The drug can remain free or
bind to the protein. The portion of a drug
that’s bound to a protein is inactive and can’t
exert a therapeutic effect. Only the free, or
unbound, portion remains active.

12. Metabolism
Drug metabolism, or biotransformation, is the process
by which the body changes a drug from its dosage form
to a more water-soluble form that can then be excreted. Drugs can
be metabolized in several ways:
• Most drugs are metabolized into Inactive metabolites
(products of metabolism), which are then excreted.
• Other drugs are converted to Active metabolites.
which are capable of exerting their own pharmacologic
action.
PRO DRUG: Some drugs can be administered as inactive drugs,
called prodrugs, which don’t become active until they’re
metabolized.

13. Excretion
Drug excretion refers to the elimination of drugs from the body.
Most drugs are excreted by the kidneys and leave the body
through urine.
Half-life = half the drug
The half-life of a drug is the time it takes for -half of the
drug
to be eliminated by the body. Factors that affect a drug’s
half-life
include its rate of absorption, metabolism, and excretion.
Knowing how long a drug remains in the body helps
determine how frequently it should be administered.

14. HALF LIFE
The half-life of a drug is the time it takes for the
amount of a drug's active substance in your body
to reduce by half. This depends on how the body
processes and gets rid of the drug. It can vary from
a few hours to a few days, or sometimes weeks.

15. PHARMACODYNAMICS:
Agonist drugs
Many drugs work by stimulating or blocking drug receptors. A
drug attracted to a receptor displays an affinity for that receptor.
When a drug displays an affinity for a receptor and stimulates it,
the drug acts as an agonist. An agonist binds to the receptor and
produces a response. This ability to initiate a response after binding with
the receptor is referred to as intrinsic activity.
Antagonist drugs
If a drug has an affinity for a receptor but displays little or no intrinsic
activity, it’s called an antagonist. An antagonist prevents a response from
occurring.

16. TYPES OF ANTAGONISTS
Antagonists can be competitive or noncompetitive.
• A competitive antagonist;
competes with the agonist for receptor sites. Because
this type of antagonist binds reversibly to the receptor
site, administering larger doses of an agonist can
overcome the antagonist’s effects.
A noncompetitive antagonist binds to receptor sites
and blocks the effects of the agonist. Administering
larger doses of the agonist can’t reverse the antagonist’s
action.

17. RECEPTORS
If a drug acts on a variety of receptors, it’s said to be nonselective
and can cause multiple and widespread effects. In addition, some
receptors are classified further by their specific effects. For
example, beta receptors typically produce increased heart rate
and
bronchial relaxation as well as other systemic effects.
Beta receptors, however, can be further divided into beta1
receptors (which act primarily on the heart) and beta2 receptors
(which act primarily on smooth muscles and gland cells).

18. Drug potency
Drug potency refers to the relative amount of a drug
required to produce a desired response. Drug potency is
also used to compare two drugs. If drug X produces the
same response as drug Y but at a lower dose, then drug X is
more potent than drug Y.

19. Potency is a measure of the amount of drug necessary
to produce an effect. The concentration of drug
producing 50% of the maximum effect is often used to
determine potency. , the EC50 for Drugs A and B
indicate that Drug A is more potent than Drug B,
because a lesser amount of Drug A is needed to obtain
50% effect. Therapeutic preparations of drugs reflect
their potency.
The smaller the Ec50 the more potent drug

20. EFFICACY
Efficacy is the magnitude of response a drug
causes when it interacts with a receptor. Efficacy
is dependent on the number of drug–receptor
complexes formed and the intrinsic activity of the
drug (its ability to activate the receptor and cause
a cellular response). Maximal efficacy of a drug
(Emax) assumes that the drug occupies all
receptors, and no increase in response is
observed in response to higher concentrations of
drug.

22. Therapeutic index
The therapeutic index (TI) of a drug is the ratio of
the dose that produces toxicity in half the
population (TD50) to the dose that produces a
clinically desired or effective response (ED50) in
half the population:
The TI is a measure of a drug’s safety, because a
larger value indicates a wide margin between
doses that are effective and doses that are toxic.
TI= TD50/ED50

23. Terminologies
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Pharmacy:
The department which prepares and dispenses
drugs.
Pharmacist:
Aperson who is licensed to prepare and dispense
drugs.
Therapeutic Drugs / Medication:
Asubstance administered for the diagnosis,
treatment, or prevention of disease.

24. Terminologies
Prescription:
Alegal order for the preparation and administration of a
medication
Indication / Uses:
It describes the purpose for which the drug is approved for
use. (i.e. for what the drug is generally used? E.g.
Panadol….Fever/ mild to moderate pain)
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25. Terminologies
Contraindications:
Instances / conditions in which the drug should not be used at
all (Panadol…liver disease)
Therapeutic effects:
The desired response of the medication, or the intended effect.
For e.g. the therapeutic effect of morphine sulphate is
analgesia (pain relief).
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26. Terminologies
Side effects:
The undesired effect of drug which is common and
expected, with the normal dose of drug.
For e.g. Side effect of antibiotics is nausea and vomiting.
Adverse effects:
More severe than side effects; Undesired responses of a drug
that are rare and unexpected.
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27. Terminologies
Drug toxicity/ Toxic effects:
When drug level exceeds the therapeutic ranges, toxic effects
occur from overdosing and drug accumulation.
DrugAllergy:
Immunological reaction of the body to a drug
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28. DRUG TOXICITY
Drug toxicity refers to the level of damage that a compound can
cause to an organism. The toxic effects of a drug are dose-
dependent and can affect an entire system as in the CNS or a
specific organ such as the liver.

29. Terminologies
Drug tolerance (decreased responsiveness of the body to drug)
Occurs when the body becomes accustomed to a particular
drug over time so that larger doses must be given to produce
the therapeutic/ desired effects.
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30. TOLERANCE AND DEPENDENCE
The main difference between tolerance and dependence is that
tolerance refers to the body getting used to taking a substance
and requiring higher doses.
Dependence, however, refers to the physical or psychological
symptoms that occur that make someone feel like they must
continue taking a substance.

31. Purposes of medications
🞇 Preventive: e.g. Vaccines for prevention of TB
🞇 Curative: e.g. Streptokinase for MI
🞇 Alleviative: supportive drug therapies (along with the main
drug regime)
🞇 Palliative : e.g. Painkillers
🞇 Diagnostic: e.g.Adenosine in Supra V
entricular Tachycardia

32. Sources of Medications
🞇 Plants:
🞇 Animals:
🞇 Minerals:
🞇 Synthesized:
Opiates, Morphine
insulin from pancreas of animals
iron and sodium chloride
antibiotics (in lab)
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33. Drugs Classification is based
on:
🞇 Body systems (GI drugs etc)
🞇 Therapeutic effects ( antiemetic, analgesic etc)
🞇 Non prescribed or over the counter drugs (OTC) versus
prescribed
🞇 Investigational drug (Used for diagnosis)
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34. Routes of Medication
Administration
🞇 PO (peroral)
🞇 I/M (intramascular)
🞇 I/V (intravenous)
🞇 SC (subcutaneous)
🞇 IT (intra-thecal)
🞇 Nasal Spray, Eye drops, Otic instillations
🞇 Inhalation (inhalers, nebulizers)
🞇 Ointments

35. Five Rights of drug
administration
🞇 Right patient
🞇 Right drug
🞇 Right Route
🞇 Right dose
🞇 Right time
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36. Drugs Nomenclature
Chemical Name/ Generic Name:
The name that describes the chemical and molecular
structure of a drug. (it’s official and non proprietary name)
e.g. Paracetamol
Trade name/ Brand Name ®:
The name given by drug manufacturer company ( it’s
proprietary name & registered) .
Proper nouns with the first letter capitalized and marked with
a circle R. For e.g. Panadol
Prototype:
Individual drug that represent properties of entire group of
drugs is called prototype. It is the standard with which new
drugs are compared. e.g. morphine is the prototype of opioid
analgesics and is a standard with which all other opioid
analgesics are compared.
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