I t gives idea about drug discovery process

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Drug Discovery & Development
Dr Sameh AM Abdelghany
Mansoura Faculty of medicine
Clinical Pharmacology Department

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Introduction
 The discovery and development of
new medicines is a long process.
 For every 5,000- 10,000 compounds,
only one of them finally receives
approval.
 The average cost to develop a
successful drug is estimated to be $1-2
billion.
 The whole process takes an average
of 10-15 years.

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A- THE DISCOVERY PROCESS
 Step 1: Understanding the disease
(Pathogenesis)
 how genes are altered?
 how specific proteins interact with each
other to affect the cellular functions?
 why something went wrong?
 It may take many years of work to turn
this basic knowledge into a new treatment.

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 Step 2: Find a “Target”:
 A target is any single
molecule, such as a gene,
enzyme, receptor, or
protein, which has a major
role in the pathogenesis of
the disease.

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 Step 3: Find a promising
molecule (lead compound):
 search for a “lead compound,”
that may act on the target to
alter the disease course.

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How to find a lead compound ?
I. Nature:
 Microorganism: many useful antibiotics
are derived from bacteria (e.g. penicillin
and aminoglycosides).
 Plants: many plants give active
ingredients such as atropine and
morphine.
 Minerals and elements: e.g. calcium.

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II. High-throughput screening:
 is the most common.
 Researchers can test thousands of
compounds against the target by the aid of
advanced computer software.
 The software has a library containing
thousands of compounds that can be tested
one by one against the target and detects
which one can interact with the target.

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III. Biotechnology:
 Scientists can genetically engineer living
systems to produce biological molecules
 e.g. insulin from genetically modified
yeasts.

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 Step 4: Preclinical Testing
 researchers turn their attention to test
drugs extensively in animals before testing
them in humans.
 Drugs also undergo tests (in more than one
animal species) to determine the possible
effects on a fetus.
 These experiments are conducted under
controlled conditions in relation to animal
ethics.

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 At the end of several years of intensive
work, and after starting with ~ 5,000 to
10,000 compounds, scientists now have
between 1-5 “candidate drugs,” which will
be studied in human through “clinical trials”.

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B- THE DEVELOPMENT PROCESS
 Investigational New Drug (IND)
Application and Safety
 Before any clinical trial can begin, the
researchers must file an Investigational New
Drug (IND) application with the U.S. Food and
Drug Administration (FDA)
 The FDA reviews the application to make sure
people participating in the clinical trials will
not be exposed to dangerous risks. It also can
stop the trial at any time.

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 Phase 1 Clinical Trial
 The candidate drug is tested in about 20 - 100
healthy volunteers for the first time. The main goal of
Phase 1 trial is to discover if the drug is safe in
humans.
 Researchers examine the pharmacokinetics,
pharmacodynamics, and side effects of the new drug.
They also determine the safe dosing range.

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 Phase 2 Clinical Trial
 The candidate drug is tested in about 100 - 500
patients with the disease under study. The main goal
of Phase 2 trial is to evaluate the effectiveness of the
new drug and examine the possible short-term side
effects.
 In the design of this trial, some patients receive the
drug, and the other part receive “placebo” (= false
drug).

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Cont.
 Both the researcher team and patients do not know
which group is taking the drug or the placebo (i.e.
double blind trial). This is done to eliminate any
psychological factors or bias regarding the effect of
the drug.
 If the drug continues to show promise, they prepare
for the Phase 3 trials.

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 Phase 3 Clinical Trial
 In Phase 3 trials researchers study the drug candidate
in a larger number (about 1,000-5,000) of patients to
generate statistically significant data about safety,
efficacy and the overall benefit-risk relationship.
 Phase 3 trials are both the costliest and longest
phase.
 Hundreds of sites around the world participate in the
study to get a large and diverse group of patients.

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 Drug Approval
 Once all three phases of the clinical trials are
complete, the sponsoring company requests FDA
approval to market the drug.
 FDA experts review the application and can either:
1) approve the drug
2) requesting more information or studies
3) reject approval.
 For most drugs, the developing company has the
exclusive rights to manufacture and sell the drug for
20 years (intellectual property rights).

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 Post-marketing surveillance (Phase 4):
 Research on a new medicine continues even after
marketing. Scientists must continue to monitor it
carefully and submit periodic reports, including cases
of rare adverse events, to the FDA.
 In addition, the FDA sometimes requires a company
to conduct additional studies on an approved drug to
evaluate long-term safety or possible risk in a specific
subgroup of patients.

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DRUG NOMENCLATURE
1. Chemical name:
o is the name given according to chemical structure of the
drug. It is usually complex and difficult to be used in
prescription.
2. Generic name:
o it is the name listed in the national formulary and used
in textbooks.
3. Brand name:
o it is the name owned by the pharmaceutical company
that manufactures the drug.

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CATEGORIES OF DRUGS
I. Over-The-Counter drugs (OTC)
 drugs that are considered relatively safe
and can be sold without physician's
prescription e.g. vitamins, antacids,
paracetamol, etc.

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II. Prescription-only drugs
 drugs that are used under medical
supervision because they are considered
to be unsafe.
 So they are dispensed only by registered
physician e.g. antibiotics, antidiabetics,
antidepressant, etc.

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III. Controlled substances
 drugs that are prescribed only by
specialized physicians and must include
their registration number on all
prescriptions forms.
 Nurses are responsible for storing
controlled substances in locked
containers.

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Categories of controlled substances
Schedule I:
 Drugs that are not approved for medical use
and have high abuse potentials e.g.
flunitrazepam (Rohypnol), heroin.
Schedule II :
 Drugs that are used medically and have high
abuse potentials: opioid analgesics (e.g.,
codeine,morphine), CNS stimulants (e.g.,
cocaine).

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Cont.
Schedule III:
 Drugs with less potential for abuse than
those in Schedules I and II, but abuse may lead
to psychological or physical dependence e.g.
benzodiazepines.
Schedule IV :
 Drugs with some potential for abuse e.g.
some appetite suppressants (e.g., mazindol,
phentermine).

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Cont.
Schedule V:
 Products containing moderate amounts of
controlled substances e.g. antidiarrheal drugs,
such as diphenoxylate and atropine (Lomotil).

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EXAMPLE OF DRUG LABELING INFORMATION

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Thanks For Listening