Traditional drug design involved origins from natural sources through accidental discoveries, not based on specific targets. Methods included random screening, trial and error using plant materials, ethnopharmacology observing indigenous drug uses, and serendipitous discoveries like penicillin. Rational drug design is target-based, using the known structure and function of targets. Methods include ligand-based approaches like quantitative structure-activity relationships (QSAR) and pharmacophore modeling, and structure-based approaches like molecular docking and de novo design using a target's 3D structure. Both traditional and rational methods have contributed to modern drug discovery.

1. TRADATIONAL AND
RATIONAL DRUG
DESIGNING
Submitted To :- Submitted By :-
Dr. Om Silakari Manish Kumar
M.Pharmacy
17301102

2. Traditional Drug Designing
• Traditional drug discovery involves the origin of
drug discovery that evolved in natural sources,
accidental events etc.
• It was not target based and not much systemised as
today.
• Improvement and advancement in pharmaceutical
science and technology made it evolutionised to
much more systemised modern drug discovery.

3. Methods of Traditional drug design
1. Random Screening
2. Trial & Error Method
3. EthnoPharmacology Approach
4. Serendipity Method
5. Classical Pharmacology

4. 1. Random Screening
 It includes random screening of synthetic
compounds/chemicals/natural products by
bioassay procedures.
 It involves two approaches:-
a) Screening of selected class of compounds like
alkaloids, flavonoids etc.
b) Screening of randomly selected plants.
 CDRI of CSIR of India screened almost 2000
plants for biological efficacy with random
screening.

5. 2. Trial & Error Method
 Trial and error includes berries, roots, leaves and
barks that could be used for medicinal purposes.
 Examples:-
• Cinchona Bark contains quinine used to reduce
fever in malaria.
• Leaves of Azadirachta indica (Neem) are used as
anti-inflammatory and antibacterial properties etc.
• Licorice roots are traditionally used to treat
stomach ulcers, bronchitis and sore throats.

6. 3. Ethnopharmacology approach
 Ethnopharmacology is the study of medicinal
plants used in specific cultural groups.
 It involves the observation, description, and
experimental investigation of indigenous drugs.
 It is based on botany, chemistry, biochemistry,
pharmacology and many other disciplines like
anthropology, archeology, and history.
 Andrographis paniculata (Kalmegh) was used
for dysentery in ethnomedicine and the
compounds responsible for the activity were
found to be andrographolides.

7. 4. Serendipity Method
 “Serendipity” refers to ‘an accidental discovery’
i.e, ‘finding one thing while looking for
something else’
 The most important example of this method is
the discovery of Penicillin by Alexander Fleming
in 1928 while doing research on influenza.
 One more example is the discovery of Cisplatin
(used in bladder cancer) while studying E.coli
bacteria.

8. 5. Classical Pharmacology
 Also known as Function based approach.
 Without the prior identification of drug target.
 Anciently, drug discovery processes were often
based on measuring a complex response in-vivo
such as
i) Prevention of experimentally induced seizures
ii) Lowering of blood sugar
iii) Suppression of inflammatory response
 Example:- Discovery of Foxglove in Europe

9. Rational Drug Designing
 Rational drug design can be broadly divided into
two categories :-
A. Development of molecules with desired
properties for targets having known structure
and function
B. Development of molecules with predefined
properties for targets whose structural
information may be or may not be known. The
unknown target information can be found by
Global gene expression data.

10. Methods for Rational drug design
 Two major types :-
1) Ligand Based Drug Designing
a) QSAR
b) Pharmacophore Perception
2) Structure Based Drug Designing
a) Docking
b) De novo drug design

11. 1) Ligand Based Drug Designing
 It relies on the knowledge of other molecules that
bind to the biological target of interest.
 In other words, a model of the biological target may
be built based on the knowledge of what binds to it
and this model in turn may be used to design new
molecules.
 In QSAR, biological activity is determined from the
physico-chemical properties of drug. So these
QSAR relationships in turn used in the prediction of
biological activity of new analogues.
Biological Activity = f (Physico-chemical properties )

12. 2) Structure Based Drug Designing
 It relies on the knowledge of 3D structure of
the biological target.
 3D Structure is obtained by either X-Ray
crystallography or NMR spectroscopy.
 Using the structure of receptor, candidate
drugs that are predicted to bind with high
affinity and selectivity to the target may be
designed.

13. Thank You