1. The Use and Misuse of
Drugs
Block 8, part i

2. Medical Drugs
Learning objectives:
• Know that disease may be treated with medicines
that contain useful drugs (e.g. penicillin is an
antibiotic, aspirin is anti-inflammatory)
• Know that some medicines, including
painkillers, help to relieve the symptoms of
disease, but do not provide a cure (for
example, aspirin, paracetamol, treatments for high
blood pressure, antidepressants and sleeping
tablets)

3. Drug use and abuse
How often do you see drugs being used?

4. What are drugs?
A drug is any chemical substance that affects the
physiological state of the body, such as how the central
nervous system (CNS) works.
Drugs can be categorized according to whether they are
legal or illegal, or by the type of effect they have on the body.
E.g. analgesics relieve pain (pain killers)
What is the difference between a medical and recreational
drug?
Write a definition for each in your note books.

5. Why people take drugs...
Medicinal drugs (e.g.
painkillers, antibiotics) are
used to treat (cure) diseases
or prevent symptoms. They
are obtained either with a
prescription or over-the-
counter at a pharmacy.
Recreational drugs (e.g.
alcohol, nicotine, ecstasy)
are used for leisure
purposes, because they
cause changes in mood,
behaviour or perception.

6. Which type of drug?

7. Why do drugs need to be controlled?
Illegal drugs have no quality control. It is impossible to know
how strong the dose is, or which substances the drugs have
been mixed (‘cut’) with. Some drugs may only be 1% pure.
Medicinal drugs can be equally dangerous.
Doctors are careful to prescribe the right
amount of medicine to prevent
patients from overdosing.
How are prescription and
over-the-counter drugs developed?

8. How are new drugs developed?

9. Drug trials
Few drugs successfully pass each stage of development.
For every new drug launched, thousands are abandoned.
To minimize bias in drug trials,
patients and doctors are not told who
receives the study drug and who
takes a placebo: an inactive
substance that looks like the drug.
This is called a double-blind
placebo-controlled trial. How
does this help?
The drug must be tested in thousands of patients to see how
effective and safe it is. Why are so many patients needed?

10. What was thalidomide?
Thalidomide was a drug used in the 1950s
and 1960s as a sleeping pill. However,
pregnant women who were given the drug
to prevent morning sickness gave birth
to babies with limb deformities.
How did this happen?
The drug manufacturers had tested thalidomide in animals,
but the tests on pregnant animals had not been completed.
Since then, drugs have had to be tested according to very
strict guidelines.
Thalidomide is now being tested for the treatment of
diseases such as leprosy and some cancers.

11. Is Caffeine a Stimulant?
Aim: to perform a double-blind, placebo-controlled trial on
the drug caffeine.
My results:
Before Taking After taking ‘Drug’
‘Drug’
Pulse rate:
(____)
Mean reaction
time:
(___)
Conclusion:
After taking the caffeine/placebo* drug my pulse __________
and my reaction time__________.
*Delete as appropriate

12. Converting Distance in Reaction Time
Distance on Ruler (cm) Reaction Time (s)
5 0.10
10 0.14
15 0.17
20 0.20
25.5 0.23
30.5 0.25

13. Recreational Drugs
Remember drugs can be categorised by their affect on the
body:
 stimulants – e.g. caffeine, cocaine, amphetamines
 depressants – e.g. alcohol, barbiturates, heroin
 hallucinogens – e.g. LSD, cannabis

14. What do stimulants do?
Stimulants speed up the activity of the nervous system by
increasing the release of neurotransmitters at certain
synapses in the brain. This causes:
 increased alertness
 improved memory and endurance
 raised heart rate and blood pressure
 reduced appetite.
Common stimulants include
caffeine, nicotine, cocaine
and ecstasy.

15. What do depressants do?
Depressants slow down the activity of the nervous system by
reducing the release of neurotransmitters at certain synapses
in the brain.
This results in sleepiness and
reduced anxiety, but high doses
can lead to addiction.
Common depressants
include alcohol, solvents
and barbiturates.
Some depressants, such as
heroin, also reduce pain.

16. Drug Research
You will be asked to give a 5 minute talk next lesson on
one particular recreational drug. You must work as a
team and include the following information in your
presentation:
• Type of Drug – Legal/Illegal and Stimulant/ Depressant/
Hallucinogen.
• Effects on the body – detailed description of what
happens when you take this drug (physically and
psychologically)
• Addiction – how addictive the drug is and steps to
overcome addiction
• Withdrawal symptoms – what can happen when an
addict stops taking the drug
• Other interesting facts – e.g. Does it have any positive
effects or medicinal uses?

17. What is tobacco?
Tobacco is made from the leaves of the
tobacco plant, which contain small
amounts of nicotine. Cigarettes are
made from finely cut and dried tobacco
leaves.
When tobacco smoke is inhaled, the
nicotine quickly enters the
bloodstream and has a stimulating
effect on the nervous system.
At high concentrations nicotine is
poisonous and is used as insecticide!

18. The dangers of smoking

19. Spot the difference
Which set of lungs would you prefer to have?

20. Nicotine
Nicotine is addictive because it increases levels of the
neurotransmitter dopamine in the brain. This produces
feelings of enjoyment and motivation.
Many smokers find it difficult to quit smoking
because of the symptoms of nicotine
withdrawal, which include:
 headaches
 anxiety and sleeplessness
 weight gain.
What type of products are
available to help smokers quit?

21. The effect of smoking on oxygen supply
Red blood cells are normally saturated with oxygen when
they leave the lungs.
alveolus in the lung Carbon monoxide in
cigarette smoke prevents red
cells from picking up oxygen.
capillary
oxygen
carbon monoxide
carbon dioxide
red blood cells

22. Smoker’s cough

23. Effect of cigarette smoke
chemicals

24. What is addiction?
A person is said to be addicted to, or dependent on, a drug
when they feel unable to stop taking it. There are two types of
addiction:
 physiological addiction –
the person is compelled to take
the drug to avoid or reduce
unpleasant or dangerous
withdrawal symptoms.
 psychological addiction –
the person is compelled to take
the drug to experience the
effect it produces, rather than to
treat withdrawal symptoms.

25. What is alcohol?
Alcohol is a family of related
substances, but most commonly refers
to ethanol – the active ingredient in
alcoholic drinks.
Alcohol is quickly absorbed into the
bloodstream, where it starts to have an
effect on the CNS.
The effects of alcohol vary from person to person and with
factors such as:
 rate of consumption
 level of food/water intake
 age and gender
 body weight/body fat.

26. The short-term effects of alcohol
Small amounts of alcohol cause a person to feel relaxed and
less inhibited. It can therefore appear to stimulate people.
However, further consumption has a depressant effect,
making reactions uncoordinated and impairing speech.
Alcohol is a diuretic, which
means it causes more urine
to be produced than normal.
This can lead to
dehydration, which
contributes to a hangover!
Alcohol also makes blood vessels dilate, leading to heat loss.

27. Effects of alcohol by dose

28. Physiological effects of alcohol

29. How much is it safe to drink?
The UK Department of Health advises that men should
drink no more than 4 units of alcohol per day, and women
no more than 3 units.
How much is 1 unit of alcohol?
Drink Units of alcohol
1 pint of strong lager 3
1 pint of bitter 2
1 pint of cider 2
175 mls of wine 2
1 alcopop 1.5
35 mls of spirit 1

30. The long-term effects of alcohol
Like all drugs, alcohol is broken down, or metabolized, by the
liver.
Over time, heavy drinking
damages liver cells, causing
them to produce fibrous scar
tissue which blocks liver
function. This is a disease
called cirrhosis.
Heavy drinkers are also at increased risk of cancer and
damage to the brain, kidney and immune system.

31. Antibiotics
Learning Objectives:
• Know what antibiotic are and what diseases they
can be used t treat
• Describe how antibiotics work
• Explain why antibiotics cannot be used to treat
viral illnesses

32. What are antibiotics?
Antibiotics are a group of drugs
used to treat bacterial infections.
They are effective against bacterial
cells but they generally leave
animal (human body) cells
unharmed.
There are two different types
of antibiotics:
 bactericidal – kill bacterial cells
 bacteriostatic – slow the growth or reproduction of
bacteria.

33. Testing antibiotics

34. Antibiotic resistance
In the presence of an antibiotic, some
bacteria can mutate leading to types
(strains) that can become resistance to
that antibiotic.
They are able to survive and
reproduce, giving rise to a population
of antibiotic-resistant bacteria.
In some cases this resistance
is evolving faster than the
development of new antibiotics.
M. tuberculosis has evolved resistance to streptomysin and
other antibiotics. Multi-drug resistant TB is still relatively
rare, but there is growing concern about its spread.

35. Antibiotic resistance: MRSA
The bacteria Staphylococcus
aureus has become resistant
to most antibiotics, including
methicillin. This methicillin-
resistant S. aureus (MRSA),
which is becoming common
in hospitals, can cause a
life-threatening infection.
Due to the emergence of antibiotic resistance, several
methods of prevention and control have been adopted:
 antibiotics should only be prescribed when needed
 patients should finish the complete course of antibiotics
 introduction of infection control in hospitals.

36. True or False?
1. Antibiotics are used to kill viruses
2. Antibiotics are medicines
3. Antibiotics are prescribed by doctors
4. Antibiotics are used to kill bacteria
5. You must finish all of the antibiotics to reduce the risk of
bacteria becoming resistant
6. Different types of antibiotic will kill different types of bacteria
7. Fungi never become resistant to antibiotics
8. MRSA are bacteria which can be killed by many antibiotics.
9. Some antibiotics weaken the cell walls of bacteria so they
die

37. Chickens raised in barns are given If you are in hospital after an operation
antibiotics you should be given antibiotics
It is really important that you always
If you have a cold you should go to the
finish a course of antibiotics even if you
doctor for some antibiotics
are feeling better
In some countries, antibiotics can be In this country you can only get
bought over the counter antibiotics from your doctor
Milking cows may have tubes of Pigs are sometimes given antibiotics to
antibiotics placed under their udders make their muscles grow faster
Some chopping boards have Animals should be given antibiotics
antibacterial substances built into them after operations