Drugs

1
Drugs
36.1 Introduction 36.2 Development of Aspirin and
cis-Platin 36.3 Key Stages of Drug
Development 36.4 Over-the-Counter Drugs and
Prescription Drugs 36.5 Narcotics and their
Adverse Effects 36.6 Stimulants and their Adverse
Effects
2
Introduction
3
36.1 Introduction (SB p.190)
Medicines and Drugs

• Medicines
• ? used to cure and prevent diseases
• Drugs
• ? alter the way that our body functions

4
36.1 Introduction (SB p.190)
Medicines and Drugs

• Most medicines contain drugs
• ? but some drugs are not medicines
• Example
• Alcohol and nicotine are not medicines but they
  are drugs
• Some drugs may or may not be medicines depending
  on ones state of health

5
36.1 Introduction (SB p.190)
Drugs Derived from Folk Remedies

• Since ancient times
• ? man has used natural materials to relieve
  pains, heal injuries and cure diseases
• Many of these folk remedies have been shown to be
  very effective

6
36.1 Introduction (SB p.190)
Drugs Derived from Folk Remedies

• With latest scientific and technological
  advancement
• ? active ingredients of folk remedies have
  been isolated (e.g. by chromatography) from
  the natural medicines
• ? their structures are identified (e.g. by
  M.S. or IR)

7
36.1 Introduction (SB p.190)
Drugs Derived from Folk Remedies

• Example
• Morphine extracted from the poppy Papaver
  somniferum
• Morphine
• ? powerful painkiller
• ? unless used carefully, morphine can be
  harmful to our bodies

8
36.1 Introduction (SB p.190)
http//www.poppies.org/gallery/
Drugs Derived from Folk Remedies
Poppies provide morphine
9
36.1 Introduction (SB p.190)
Drugs Derived from Folk Remedies

• Example
• Salicylic acid isolated from willow bark
• Salicylic acid
• ? the precursor of aspirin

10
36.1 Introduction (SB p.190)
Drugs Derived from Folk Remedies
Willow bark contains salicylic acid, which is the
precursor of aspirin
11
Development of Aspirin andcis-Platin
12
36.2 Development of Aspirin and cis-Platin (SB
p.191)
Aspirin

• For a long time, the bark of the willow tree
  (salix alba)
• ? used as a traditional medicine
• ? relieve the symptom of fever

• http//en.wikipedia.org/wiki/Aspirin

13
36.2 Development of Aspirin and cis-Platin (SB
p.191)
Aspirin

• In the 1860s, chemists showed
• ? salicylic acid (2-hydroxybenzoic acid) in
  willow bark
• ? as active ingredient

14
36.2 Development of Aspirin and cis-Platin (SB
p.191)
Aspirin

• By 1870, salicylic acid was widely used as
• ? painkiller (analgesic)
• ? fever depressant (antipyretic)

15
36.2 Development of Aspirin and cis-Platin (SB
p.191)
Aspirin

• The undesirable side effects of salicylic acid
• 1. irritating and damaging the lining of the
  mouth and stomach

2. causing allergy to some people
16
36.2 Development of Aspirin and cis-Platin (SB
p.191)
Aspirin

• Molecular modification is necessary
• ? give a derivative
• ? effective as salicylic acid but has less
  undesirable side effects

17
36.2 Development of Aspirin and cis-Platin (SB
p.191)
Aspirin
(a)
(b)
Structures of (a) salicylic acid (b) aspirin
18
36.2 Development of Aspirin and cis-Platin (SB
p.191)
In 1897
Acetylation of salicylic acid to produce aspirin
19

• Aspirin is a common over-the-counter drug.

Prescription drugs prescribed by doctors
20
36.2 Development of Aspirin and cis-Platin (SB
p.191)
Aspirin
Aspirin is only slightly soluble in water.
Suggest how you can prepare a water-soluble
aspirin.
21
36.2 Development of Aspirin and cis-Platin (SB
p.191)

• Let's Think 1

Example 36-2
22
36.2 Development of Aspirin and cis-Platin (SB
p.192)
Aspirin

• At present, aspirin is still widely used in the
  world
• 35000 tonnes of aspirin are produced annually
  (each tablet has 300 mg aspirin)
• Calculate the total number of aspirin tablets
  produced per year.

23
36.2 Development of Aspirin and cis-Platin (SB
p.192)
Aspirin

• Recent researches have shown that small daily
  doses of aspirin may help prevent diseases
• ? such as heart attack, stroke, and the
  blindness and kidney damage suffered by many
  patients with diabetes

Check Point 36-2
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36.2 Development of Aspirin and cis-Platin (SB
p.193)
cis-Platin
http//en.wikipedia.org/wiki/Cisplatin

• In 1964, the biophysicist, Barnett Rosenberg and
  his research group were studying the effect of an
  electric field on the growth of bacteria
• ? A platinum-containing substance extracted
  from the bacterial culture inhibited cell
  division

25
36.2 Development of Aspirin and cis-Platin (SB
p.193)
cis-Platin
square planar
cis-diamminedichloroplatinum(II) Pt(NH3)2Cl2,
26
36.2 Development of Aspirin and cis-Platin (SB
p.193)
cis-Platin

• cis-platin alters the DNA of the cancer cell
• ? when the cell tries to replicate, its DNA
  cannot be copied correctly
• ? the cell dies

27
36.2 Development of Aspirin and cis-Platin (SB
p.193)
cis-Platin

• The geometry of cis-platin is important to its
  action
• The geometrical isomer of cis-platin,
  trans-platin, was ineffective in treating cancer

28
36.2 Development of Aspirin and cis-Platin (SB
p.193)
trans-Platin
Structure of trans-platin. It is ineffective in
treating cancer.
29
36.2 Development of Aspirin and cis-Platin (SB
p.193)
cis-Platin

• Tests on animals conducted to investigate
• 1. how this compound affects cell division in
  mammalian cells
• 2. toxic side effects
• 3. different dose levels

? Clinical tests on patients
30
36.2 Development of Aspirin and cis-Platin (SB
p.193)
cis-Platin

• The most severe side effects
• ? nausea
• ? vomiting
• ? toxicity to the kidney
• ? toxicity to the bone marrow

31
36.2 Development of Aspirin and cis-Platin (SB
p.193)
cis-Platin
The use of cis-platin as an anticancer agent
32
Key Stages ofDrug Development
33
36.3 Key Stages of Drug Development (SB p.194)
Key Stages of Drug Development
1. Lead compound(?????) discovery 2. Molecular
modification 3. Safety tests and human
trials 4. Formulation(??) development 5. Approval
for marketing
34
36.3 Key Stages of Drug Development (SB p.196)
The process of drug testing and approval for
human use
35
36.3 Key Stages of Drug Development (SB p.194)
Lead compound discovery

• Lead compound
• ? a compound with some desired biological
  activities
• ? can be characterized and modified to
  produce another compound with better
  therapeutic effects but less unwanted side
  effects

36
36.3 Key Stages of Drug Development (SB p.194)
Lead compound discovery

• Development of lead compound

1. Understand how the body functions at
molecular levels both normally and abnormally 2.
Identify the target site responsible for a
specific disease 3. Develop the lead compound
with therapeutic actions on the target site
37
36.3 Key Stages of Drug Development (SB p.194)
Lead compound discovery

• Computer programs can be used to facilitate the
  design of chemical structures that are effective

Combinatorial Chemistry involves the rapid
synthesis or the computer simulation of a large
number of different but structurally related
molecules or materials

• Hundreds of thousands of compounds are screened
  to find out the lead compound which shows most
  desirable effects.

38
36.3 Key Stages of Drug Development (SB p.195)
Molecular modification

• The lead compound may have undesirable side
  effects
• Researchers need to modify the molecular
  structure of the lead compound
• ? improve its performance

39
36.3 Key Stages of Drug Development (SB p.195)
Safety Tests and Human Trials
1. Pre-clinical Research

• Once the lead compounds have been identified and
  modified

• Using cell cultures in a petri dish
• ? to determine the effectiveness of compounds

40
36.3 Key Stages of Drug Development (SB p.195)
1. Pre-clinical Research

• The most effective compounds are then subject to
  animal assays
• Both short-term and long-term testing are
  conducted on animals
• to investigate the mechanisms, toxicity and
  adverse side effects

41
36.3 Key Stages of Drug Development (SB p.195)
2. Clinical Research
(a) Phase 1

• The first time that the drug is tested on humans
• Generally, 20 to 80 healthy volunteers,
• ? but sometimes patients are involved in this
  phase of research

42
36.3 Key Stages of Drug Development (SB p.195)
2. Clinical Research
(a) Phase 1
To investigate the metabolism, the
structure-reactivity relationships, the mechanism
of action and the side effects of the drug in
humans
43
36.3 Key Stages of Drug Development (SB p.195)
2. Clinical Research
(a) Phase 2

• The purpose of phase 2 clinical research is to
  determine
• ? the effectiveness of the drug to treat
  patients with a specific disease or condition
• ? common short-term side effects or risks

44
36.3 Key Stages of Drug Development (SB p.195)
2. Clinical Research
(a) Phase 2

• These studies are conducted on a larger scale
  than the phase 1 studies
• ? several hundreds of patients are involved

45
36.3 Key Stages of Drug Development (SB p.196)
2. Clinical Research
(a) Phase 3

• Phase 3 clinical research aims to
• ? provide more information about the
  effectiveness and the safety of the drug
• ? a still greater no. of patients are involved
  to allow scientists to extrapolate the results
  of clinical research to the general population

46
36.3 Key Stages of Drug Development (SB p.195)
Formulation Development

• There are various routes of administration of a
  drug
• Each route requires different types of formulation

47
36.3 Key Stages of Drug Development (SB p.195)
Formulation Development

• For oral route
• ? the drug can be in the form of tablets,
  capsules or liquid
• For parenteral(????) route
• ? it can be in ampoules(??) or intravenous
  fluid(?????)

48
36.3 Key Stages of Drug Development (SB p.195)
Formulation Development

• Researchers have to find out
• ? which formulation of the drug brings the
  greatest effect
• ? is the most suitable to the patients

49
36.3 Key Stages of Drug Development (SB p.196)
Approval for Marketing

• When the drug has passed all the phases of the
  clinical research
• ? the pharmaceutical company of the drug needs
  to make a formal application to the regulatory
  authority (like Food and Drug
  Administration in the US) for approving

50
36.3 Key Stages of Drug Development (SB p.196)
Approval for Marketing

• The application must include
• ? a description of how the drug was
  manufactured
• ? results and analyses from the tests of the
  drug on both animals and humans

51
36.3 Key Stages of Drug Development (SB p.196)
Approval for Marketing

• The application must provide sufficient
  information for the regulatory authority to make
  several critical decisions
• ? whether the drug is safe and effective
• ? whether its benefits outweigh its risks

52
36.3 Key Stages of Drug Development (SB p.196)
Approval for Marketing
? whether the drugs labelling information
is appropriate
? whether the manufacturing methods used to
make the drug are adequate for ensuring the
purity and integrity of the drug
53
36.3 Key Stages of Drug Development (SB p.196)
Approval for Marketing

• Phase 4 clinical research is done after the drug
  has been approved to be sold in the market
• The main purposes of phase 4 are to find
• ? more about the side effects and safety of
  the drug

54
36.3 Key Stages of Drug Development (SB p.196)
Approval for Marketing

• The main purposes of phase 4 are to find
• ? what the long-term risks and benefits are
• ? how well the drug works when it is used
  more widely than in clinical research

55
36.3 Key Stages of Drug Development (SB p.196)
Approval for Marketing

• The process of developing and testing a new drug
  is a lengthy one
• it takes about 10 years to develop a drug at a
  cost of 1 billion US dollars

Check Point 36-3
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Over-the-Counter Drugs and Prescription Drugs
57
36.4 Over-the-Counter Drugs and Prescription
Drugs (SB p.197)
Over-the-Counter Drugs and Prescription Drugs

• Drugs can be divided into two categories based on
  how they can be bought
• ? Over-the-counter (non-prescription) drugs
• ? Prescription drugs

58
36.4 Over-the-Counter Drugs and Prescription
Drugs (SB p.197)
Structure and uses of some common
over-the-counter drugs
Name Structure Uses
Aspirin (e.g. Cortal) As analgesics and antipyretics
Acetaminophen (e.g. Panadol) As analgesics and antipyretics
59
36.4 Over-the-Counter Drugs and Prescription
Drugs (SB p.197)
Structure and uses of some common
over-the-counter drugs
Name Structure Uses
Vitamin C Helps maintain elasticity of the skin, aids the absorption of iron and improves resistance to infection Essential for the formation of collagen and intercellular material, bone and teeth and for healing of wounds
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Aspirin Analgesics and antipyretics
60
61
Acetaminophen Analgesics and antipyretics
61
62
Vitamin C Helps maintain elasticity of the skin,
aids the absorption of iron and improves
resistance to infection.
62
63
36.4 Over-the-Counter Drugs and Prescription
Drugs (SB p.198)
Structure and uses of some common prescription
drugs
Name Structure Uses
Albuterol For treating asthma, emphysema(???) and chronic bronchitis Dilates the bronchial airways by relaxing the surrounding muscles
Amoldipine As an anti-hypertensive
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Albuterol Treating asthma, emphysema and chronic
bronchitis
64
65
36.4 Over-the-Counter Drugs and Prescription
Drugs (SB p.198)
Structure and uses of some common prescription
drugs
Name Structure Uses
Amoxicillin (E.g. Augmentin) As an antibiotic used to treat bacterial infections
Omeprazole Suppresses secretion of gastric acid Used for the treatment of duodenal and gastric ulcers and gastroesophageal reflux disease(?????)
66
36.4 Over-the-Counter Drugs and Prescription
Drugs (SB p.198)
Name Structure Uses
Chlorpheniramine (e.g. Coltalin, Dristan) Brompheniramine (e.g. Neosed, ??) Relieves nasal and non-nasal symptoms of common cold and allergies (e.g. runny nose, itchy eyes, watery eyes, sneezing) As an antihistamine
Loratadine (e.g. ?????) - Ditto -
Br
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Halogenated pheniramines are up to 20-fold more
potent than pheniramine
68
36.2 Development of Aspirin and cis-Platin (SB
p.191)

• Let's Think 1

We do not want to rely on the natural products
(like willow trees) as medicines (like salicylic
acid). Why?
Medicines which are natural products (e.g.
those which come directly from plants) may be
difficult to obtain when needed. The supply may
be seasonal, may depend on weather conditions and
may be liable to contamination. Collecting plants
from their natural habitat may cause harms to the
environment.
Back
Anise for Tamiflu
69
36.2 Development of Aspirin and cis-Platin (SB
p.192)

• Example 36-2

At the end of the 19th century, the compound
phenol was already well-known in the
pharmaceutical industry. Phenol has germicidal
properties. It was also readily available and its
molecular structure differs from that of
2-hydroxybenzoic acid by only one functional
group. Phenol 2-Hydroxybenzoic acid
70
36.2 Development of Aspirin and cis-Platin (SB
p.192)

• Example 36-2

(a) What extra atoms have to be added to phenol
to give 2-hydroxybenzoic acid?
Answer
(a) 1 carbon atom and 2 oxygen atoms
71
36.2 Development of Aspirin and cis-Platin (SB
p.192)
Back

• Example 36-2

(b) Suggest reagents and conditions necessary to
bring about the change from phenol to
2-hydroxybenzoic acid.
Answer
72
36.2 Development of Aspirin and cis-Platin (SB
p.192)

• Check Point 36-2

Aspirin belongs to a class of organic compounds
known as esters. Esterification of salicylic acid
with a reagent is used to produce
aspirin. (a) Suggest reagents for converting
salicylic acid to aspirin in the esterification.
Answer
(a) Ethanoyl chloride and ethanoic anhydride may
be used.
73
36.2 Development of Aspirin and cis-Platin (SB
p.192)

• Check Point 36-2

Aspirin belongs to a class of organic compounds
known as esters. Esterification of salicylic acid
with a reagent is used to produce
aspirin. (b) Write a chemical equation for the
reaction involved.
Answer
74
36.2 Development of Aspirin and cis-Platin (SB
p.192)

• Check Point 36-2

75
36.2 Development of Aspirin and cis-Platin (SB
p.192)
Back

• Check Point 36-2

76
36.3 Key Stages of Drug Development (SB p.197)

• Check Point 36-3

(a) What is the lead compound of aspirin?
(a) 2-Hydroxybenzoic acid (or salicylic acid)
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36.3 Key Stages of Drug Development (SB p.197)

• Check Point 36-3

(b) Why is molecular modification of the lead
compound of aspirin necessary?
(b) It is because the lead compound of aspirin
has many undesirable effects. It irritates and
damages the lining of the mouth and stomach.
Back
78
36.4 Over-the-Counter Drugs and Prescription
Drugs (SB p.199)

• Check Point 36-4

cis-Platin is a prescription drug. (a) What is
the meaning of a prescription drug?
(a) A prescription drug means that the use of
the drug must be prescribed by a medical doctor.
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36.4 Over-the-Counter Drugs and Prescription
Drugs (SB p.199)

• Check Point 36-4

cis-Platin is a prescription drug. (b) Why is
cis-platin regarded as a prescription drug?
(b) cis-Platin is a prescription drug because it
has numerous side effects on our health. A
professional decision from the medical doctor is
necessary for its adminstration.
Back