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Chapter 35 Drugs

35.1 Introducing drugs

35.2 Anti-acids

35.3 Analgesics

35.4 Problems with drugs

35.5 Hazards of cigarette smoking

CONTENTS OF CHAPTER 35

35.6 Working towards a smokeless Hong Kong

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35.1 INTRODUCING DRUGS

35.1 INTRODUCING DRUGS

MEDICINES AND DRUGS

Medicines are substances used to cure or prevent diseases. Most

medicines consist of one or more drugs.

A drug is a substance which changes the state or function of the

human body.

Alcohol, Milk of Magnesia, aspirin and penicillin are common

examples.

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COMMON TYPES OF DRUGS

Drugs fall into a number of types.

Anti-acids

The word anti-acid means ‘opposite to acid’, often abbreviated as

antacid.

Anti-acids relieve stomach trouble. They act by neutralizing

excess acid in the stomach.

35.1 INTRODUCING DRUGS

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Figure 35.2

Milk of magnesia is an

anti-acid.

35.1 INTRODUCING DRUGS

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Analgesics

Analgesics are painkillers, that is, they relieve pain.

35.1 INTRODUCING DRUGS

Figure 35.3 Panadol is an analgesic.

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35.1 INTRODUCING DRUGS

Antibiotics

Antibiotics are used to treat bacterial infections.

Figure 35.4 Keflex is an antibiotic.

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Anti-histamines

Anti-histamines are used to treat allergy. They are effective in

relieving hay fever and allergic rashes.

Figure 35.5 Polaramine is an anti-histamine.

35.1 INTRODUCING DRUGS

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Hypnotics

Hypnotics cause sleepiness.

Figure 35.6 Barbiturates are hypnotics.

35.1 INTRODUCING DRUGS

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Tranquillisers

Tranquillisers are substances which relieve tension and anxiety.

Figure 35.7 Valium is a tranquilliser.

35.1 INTRODUCING DRUGS

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A35.1

Penicillin is an effective antibiotic. It has saved many lives from

bacterial infections since the 1940s.

35.1 INTRODUCING DRUGS

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35.2 ANTI-ACIDS

35.2 ANTI-ACIDS

WHAT ARE ANTI-ACIDS?

We can take anti-acids to neutralize the excess acid in the

stomach. They usually contain chemicals such as:

magnesium hydroxide

aluminium hydroxide

magnesium carbonate

calcium carbonate

sodium hydrogencarbonate

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Figure 35.8 Anti-acid tablets.

35.2 ANTI-ACIDS

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A35.2

Dyspepsia (or indigestion): difficulty in digesting food

Heartburn: a burning feeling just below the heart, caused by

indigestion

Acid stomach: too much acid (gastric juice) produced in stomach,

causing pain

Flatulence: Uneasy feeling caused by gas generated in the

alimentary canal

35.2 ANTI-ACIDS

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MAGNESIUM HYDROXIDE/ ALUMINIUM HYDROXIDE

AS ACTIVE INGREDIENT

Magnesium hydroxide is slightly soluble in water, forming an

alkaline suspension. It can thus neutralize the hydrochloric acid in

stomach:

Mg(OH)2(s) + 2HCl(aq) MgCl2(aq) + 2H2O(l)

35.2 ANTI-ACIDS

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Figure 35.9 Magnesium hydroxide is the active ingredient of Philips’ Milk of Magnesia.

35.2 ANTI-ACIDS

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35.2 ANTI-ACIDS

Activity 2

Brief guidelines for the project are as follows:

A. To find the best buy according to greatest ‘neutralizing power’

per unit dollar

B. Comparison of the actions and side-effects on the active

ingredients

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35.2 ANTI-ACIDS

C. Other comparisons

• Size of packet

• Packaging

• Appearance of tablet (colour, size, shape etc.)

• Instructions to users on safe administration of drugs

• Availability in local market

D. Conclusion

Based on comparisons in Parts A, B and C, decide, as

objectively as possible, which brand of anti-acid tablets is of

the best buy. Give your reasoning.

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CARBONATE / HYDROGENCARBONATE AS ACTIVE

INGREDIENT

Carbonates or hydrogencarbonates neutralize acid in stomach

rapidly.

MgCO3(s) + 2HCl(aq) MgCl2(aq) + CO2(g) + H2O(l)

NaHCO3(s) + HCl(aq) NaCl(aq) + CO2(g) + H2O(l)

However, the effect is only short-lasting.

35.2 ANTI-ACIDS

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Figure 35.10

Magnesium carbonate and sodium hydrogencarbonate are the

active ingredients in this brand of anti-acid.

35.2 ANTI-ACIDS

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35.2 ANTI-ACIDS

‘Bismag’ antacid tablets react with dilute hydrochloric acid.

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35.3 ANALGESICS

35.3 ANALGESICS

WHAT ARE ANALGESICS?

Analgesics (or painkillers) are drugs to relieve pain.

The active ingredient in common analgesics is usually one

(or sometimes both) of the following compounds:

Aspirin

Paracetamol (also called acetaminophen)

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Figure 35.12 Some brands of analgesics.

35.3 ANALGESICS

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(a) (b) (c)

Figure 35.13

Common analgesics contain aspirin and/or paracetamol (acetaminophen) as the active

ingredient.

(a) Aspirin and Cortal contain aspirin.

(b) Panadol, Tylenol and Saridon contain paracetamol.

(c) Exedrin contains both aspirin and paracetamol.

35.3 ANALGESICS

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THE WONDER DRUG — ASPIRIN

Aspirin is the drug which is most widely used as a medicine. It

relieves pains (e.g. headache, toothache), and can reduce fever

(due to infectious diseases and colds) and inflammation.

Aspirin is the common name given to acetylsalicylic acid or

sodium acetylsalicylate.

35.3 ANALGESICS

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Figure 35.17 Beautiful willow trees. Aspirin was first made from willow bark.

35.3 ANALGESICS

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Figure 35.18 Formulae of the two forms of aspirin.

35.3 ANALGESICS

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Figure 35.19 One brand of soluble aspirin.

35.3 ANALGESICS

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35.4 PROBLEMS WITH DRUGS

35.4 PROBLEMS WITH DRUGS

SIDE EFFECTS OF DRUGS

Drugs may have undesirable side effects. Let us look at some

examples.

Aspirin irritates the stomach.

Some cough mixtures contain codeine. These may cause

drowsiness and possible addiction.

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Figure 35.21 This cough mixture contains a little codeine.

35.4 PROBLEMS WITH DRUGS

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A35.3

We should take aspirin after meal, together with a lot of water or

milk.

DRUG ABUSE

What is drug abuse?

Drug abuse includes the following:

Obtaining and using drugs (which should be prescribed)

without a doctor’s prescription.

Taking drugs for no medical reasons.

35.4 PROBLEMS WITH DRUGS

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Taking drugs exceeding the recommended dosage.

Taking a hypnotic or tranquilliser continually for a long period

of time, without a doctor’s guidance.

Sniffing solvents (e.g. glue, thinner, petrol).

Taking illegal drugs (e.g. cannabis, cocaine, heroin and LSD).

(This is particularly dangerous and will surely lead to early

death.)

35.4 PROBLEMS WITH DRUGS

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Figure 35.22

Some commonly abused drugs in

Hong Kong.

35.4 PROBLEMS WITH DRUGS

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DRUG DEPENDENCE

A person addicted to a drug is either physically or psychologically

dependent on the drug, or both.

Physical dependence

Psychological dependence

35.4 PROBLEMS WITH DRUGS

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The following guiding questions may be useful for this discussion:

(1) What are drugs?

(2) What are the main types of drugs and their uses?

(3) What are the side effects of drugs?

(4) What is drug abuse?

(5) What are the harmful effects of drug abuse?

(6) Is drug abuse serious in Hong Kong?

35.4 PROBLEMS WITH DRUGS

Activity 4

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HARMS OF DRUG ADDICTION

Harm to drug addicts themselves

Harm to families of drug addicts

Harm to society

DRUG ABUSE IN HONG KONG

In recent years, there has been a rising trend in the number of

young people taking illegal drugs.

35.4 PROBLEMS WITH DRUGS

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Figure 35.23 Government posters against drug abuse.

35.4 PROBLEMS WITH DRUGS

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35.5 HAZARDS OF CIGARETTE SMOKING

35.5 HAZARDS OF CIGARETTE SMOKING

SMOKING CAN KILL

You may have seen many times the government health warning:

‘Smoking can kill’. This warning is no exaggeration at all.

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Figure 35.24 Hong Kong Government health warning: ‘Smoking can kill.’

35.5 HAZARDS OF CIGARETTE SMOKING

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Figure 35.25

A government anti-smoking

poster.

35.5 HAZARDS OF CIGARETTE SMOKING

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TRAPPING CIGARETTE SMOKE

We can trap smoke from a lit cigarette using a ‘cigarette smoking

machine’.

35.5 HAZARDS OF CIGARETTE SMOKING

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Figure 35.26 A ‘cigarette smoking machine’.

35.5 HAZARDS OF CIGARETTE SMOKING

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Experiment results show that high-tar cigarettes without filters

give out more tar than low-tar cigarettes with filters. Besides,

smokers inhale more harmful substances than passive smokers

do.

HARMFUL SUBSTANCES IN CIGARETTE SMOKE

Smoking produces more than 4000 chemicals. The main products

are:

Gases (or vapours)

Carbon dioxide

Carbon monoxide

Polycyclic aromatic hydrocarbons (PAHs)

35.5 HAZARDS OF CIGARETTE SMOKING

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Tar

Nicotine

Particulates

35.5 HAZARDS OF CIGARETTE SMOKING

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35.5 HAZARDS OF CIGARETTE SMOKING

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A35.4

Tar.

A35.5

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35.5 HAZARDS OF CIGARETTE SMOKING

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Activity 6

Discussion could be based on the following points:

(1) Why do people smoke?

(2) Should smoking be banned completely? Why?

(3) Should smoking be restricted (e.g. in public areas)?

(4) If smoking is to be restricted, how should this be done?

(5) Should cigarette advertising be restricted? Why?

(6) Is restriction on cigarette advertising a violation of freedom of

speech?

35.5 HAZARDS OF CIGARETTE SMOKING

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(7) Should sponsorship for entertainments from cigarette

companies be forbidden?

(8) Do you think that the health hazard warnings on cigarette

smoking mentioned on cigarette packets and advertisements

are effective?

35.5 HAZARDS OF CIGARETTE SMOKING

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SUMMARY

1. A drug is a substance which changes the state or function of

the human body.

2. Anti-acids are drugs that can relieve stomach trouble caused

by excess acid in the stomach. Milk of magnesia, with

magnesium hydroxide as the active ingredient, is a common

anti-acid.

3. Aspirin is a common painkiller, with acetylsalicylic acid as the

active ingredient. Panadol is another common painkiller, with

paracetamol as the active ingredient.

4. Drugs may have adverse side effects.

SUMMARY

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SUMMARY

5. Drug abuse is very dangerous.

6. There are two types of drug dependence — physical

dependence and psychological dependence.

7. Smoking of cigarettes releases many harmful substances,

including:

Carbon monoxide

Polycyclic aromatic hydrocarbons

Tar

Nicotine

Particulates