The Use and Misuse of Drugs

Block 8, part i

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)

Drug use and abuseHow often do you see drugs being used?

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.

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.

Which type of drug?

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.

Why do drugs need to be controlled?

Medicinal drugs can be equally dangerous. Doctors are careful to prescribe the right amount of medicine to prevent patients from overdosing.

How are prescription andover-the-counter drugs developed?

How are new drugs developed?

Drug trialsFew drugs successfully pass each stage of development. For every new drug launched, thousands are abandoned.

The drug must be tested in thousands of patients to see how effective and safe it is. Why are so many patients needed?

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?

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 birthto babies with limb deformities.

What was thalidomide?

Since then, drugs have had to be tested according to very strict guidelines.

The drug manufacturers had tested thalidomide in animals, but the tests on pregnant animals had not been completed.

How did this happen?

Thalidomide is now being tested for the treatment of diseases such as leprosy and some cancers.

Is Caffeine a Stimulant?Aim: to perform a double-blind, placebo-controlled trial on

the drug caffeine.

My results:Before Taking ‘Drug’

After taking ‘Drug’

Pulse rate:(____)

Mean reaction time:(___)

Conclusion:After taking the caffeine/placebo* drug my pulse __________ and my reaction time__________. *Delete as appropriate

Converting Distance in Reaction TimeDistance 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

Recreational DrugsRemember drugs can be categorised by their affect on the

body:

depressants – e.g. alcohol, barbiturates, heroin

stimulants – e.g. caffeine, cocaine, amphetamines

hallucinogens – e.g. LSD, cannabis

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:

Common stimulants include caffeine, nicotine, cocaine and ecstasy.

improved memory and endurance

increased alertness

raised heart rate and blood pressure

reduced appetite.

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.

Common depressants include alcohol, solvents and barbiturates.

This results in sleepiness and reduced anxiety, but high doses can lead to addiction.

Some depressants, such as heroin, also reduce pain.

Drug ResearchYou 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?

What is tobacco?

When tobacco smoke is inhaled, the nicotine quickly enters the bloodstream and has a stimulating effect on the nervous system.

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.

At high concentrations nicotine is poisonous and is used as insecticide!

The dangers of smoking

Spot the differenceWhich set of lungs would you prefer to have?

NicotineNicotine 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:

What type of products are available to help smokers quit?

headaches

anxiety and sleeplessness

weight gain.

The effect of smoking on oxygen supply

oxygen

carbon monoxide

carbon dioxide

Red blood cells are normally saturated with oxygen when they leave the lungs.

Carbon monoxide in cigarette smoke prevents red cells from picking up oxygen.

alveolus in the lung

capillary

red blood cells

Smoker’s cough

Effect of cigarette smoke chemicals

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:

psychological addiction –the person is compelled to take the drug to experience the effect it produces, rather than to treat withdrawal symptoms.

physiological addiction –the person is compelled to take the drug to avoid or reduce unpleasant or dangerous withdrawal symptoms.

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

body weight/body fat.

age and gender

The short-term effects of alcohol

Alcohol also makes blood vessels dilate, leading to heat loss.

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!

Effects of alcohol by dose

Physiological effects of alcohol

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?

3

2

2

2

1.5

1

1 pint of strong lager

1 pint of bitter

1 pint of cider

1 alcopop

175 mls of wine

35 mls of spirit

Drink Units of alcohol

Like all drugs, alcohol is broken down, or metabolized, by the liver.

The long-term effects of alcohol

Heavy drinkers are also at increased risk of cancer and damage to the brain, kidney and immune system.

Over time, heavy drinking damages liver cells, causing them to produce fibrous scar tissue which blocks liver function. This is a disease called cirrhosis.

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

Antibiotics

What are antibiotics?

Antibiotics are a group of drugs used to treat bacterial infections.

bactericidal – kill bacterial cells bacteriostatic – slow the growth or reproduction of

bacteria.

They are effective against bacterial cells but they generally leave animal (human body) cells unharmed.

There are two different types of antibiotics:

Testing antibiotics

Antibiotic resistanceIn the presence of an antibiotic, some bacteria can mutate leading to types (strains) that can become resistance to that antibiotic.

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.

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.

Antibiotic resistance: MRSAThe 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.

True or False?

1. Antibiotics are used to kill viruses2. Antibiotics are medicines3. Antibiotics are prescribed by doctors4. Antibiotics are used to kill bacteria5. You must finish all of the antibiotics to reduce the risk of

bacteria becoming resistant6. Different types of antibiotic will kill different types of bacteria7. Fungi never become resistant to antibiotics8. MRSA are bacteria which can be killed by many antibiotics.9. Some antibiotics weaken the cell walls of bacteria so they die

Chickens raised in barns are given antibiotics

If you are in hospital after an operation you should be given

antibiotics

If you have a cold you should go to the doctor for some antibiotics

It is really important that you always finish a course of antibiotics even if

you are feeling better

In some countries, antibiotics can be bought over the counter

In this country you can only get antibiotics from your doctor

Milking cows may have tubes of antibiotics placed under their udders

Pigs are sometimes given antibiotics to make their muscles grow faster

Some chopping boards have antibacterial substances built into

them

Animals should be given antibiotics after operations