Drugs and drug testing

Drugs

Drugs are substances that cause changes to the body. Some drugs can help the body, but others can harm it. Some drugs can be extracted from natural sources and their existence has been known about for a long time. For example, willow bark is known to have been used by the ancient Greeks to help cure fevers and pains. It was later discovered that the active ingredient was salicylic acid. This was modified by chemists into the substance we call aspirin, which is less irritating to the stomach than salicylic acid.

Drug testing

New medical drugs have to be tested before they can be prescribed for patients. They are tested in a laboratory to check that they are not toxic, and later they are trialled using human volunteers. At this point, any potential side effects should show themselves. Most substances do not pass all the tests and trials, so drug development is expensive and takes a long time.

Medical drug trials are not without risk. Sometimes very severe and unexpected side-effects appear.

Thalidomide

Thalidomide is a drug that was prescribed during the late 1950s and early 1960s. It was developed as a sleeping pill, but it was also thought to be useful for easing morning sickness in pregnant women. Unfortunately, it had not been tested for use in this way.

Birth defects

A boy with stunted growth to the arms and legs due to the effects of thalidomide

By 1960, thalidomide was found to damage the development of unborn babies, especially if it had been taken in the first four to eight weeks of pregnancy. The drug led to the arms or legs of the babies being very short or incompletely formed. More than 10,000 babies were affected around the world. As a result of this disaster, thalidomide was banned.

Thalidomide today

Thalidomide is now used as a treatment for leprosy and bone cancer. Its use is heavily regulated, however, to prevent a repeat of the problems it caused in the last century.

Tobacco

Warnings such as 'Smoking can cause a slow and painful death' are used to deter people from smoking

About 114,000 people die every year as a result of smoking-related illnesses. All cigarettes sold now carry a prominent health warning.

Cigarettes contain about 4,000 different chemicals, many of which are harmful to the body.

Nicotine

Nicotine is the addictive substance in tobacco smoke. It reaches the brain within 20 seconds and creates a dependency so that smokers become addicted.

Carbon monoxide

Carbon monoxide combines with the haemoglobinhaemoglobin: The red protein found in red blood cells that transports oxygen round the body in red blood cells and so reduces the ability of the blood to carry oxygen. This puts extra strain on the circulatory system, and can cause an increased risk of heart disease and strokes.

Smoking during pregnancy is very dangerous. It reduces the amount of oxygen available to the growing fetus. This leads to an increased risk of

• miscarriage and premature birth
• low weight of babies at birth

Carcinogens

Carcinogens are substances that cause cancer. Tobacco smoke contains many carcinogens, including tar. Smoking increases the risk of lung cancer, mouth cancer and throat cancer.

A healthy lung

A smoker's lung, with tar deposits visible

The images above compare a healthy lung to a smoker’s lung. Tar deposits can be seen clearly in the smoker’s lung.

Alcohol

Alcoholic drinks

The alcohol in alcoholic drinks such as wines, beer and spirits is ethanol. It is a depressant. This means that it slows down signals in the nerves and brain.

Small amounts of alcohol help people to relax, but greater amounts lead to a lack of self-control. Drinkers of alcohol may not realise how much they are consuming, and fall ill as a result. They may become unconscious, and may even fall into a coma.

Long-term effects of alcohol include damage to the liver and brain. Alcohol may also cause weight gain, and it is addictive.

Legal and illegal drugs

Legal drugs are drugs that are prescribed to a patient by their doctor or bought over the counter. Illegal drugs include prescription drugs that have been dangerously modified and substances that are banned by law.

Recreational drugs

Recreational drugs are taken by people to alter their mood.

• alcohol and tobacco are legal recreational drugs
• heroin and cocaine are illegal recreational drugs

Many drugs alter the chemical processes in the body in such a way that the person taking them becomes addicted to them. They feel they have to take the drugs, and they suffer unpleasant withdrawal symptoms if they stop taking them. All four drugs listed above are addictive. Heroin and cocaine are very addictive, and may cause permanent mental problems.

The impact on health

All drugs have the potential to damage our health, because they change chemical processes in the body. Addictive recreational drugs may damage our health indirectly by reducing the amount of money available to buy food, and by placing users in dangerous situations. Injecting any drug with a needle and syringe that someone else has used may lead to a number of diseases from infected blood, including HIV and hepatitis. Users of illegal drugs may turn to crime to pay for their habit, and this affects the lives of other people.

A research report in 2006 classified various drugs according to their health and social risks, without reference to whether they are legal or not. In the report, heroin and cocaine are the most dangerous two drugs, alcohol is the fifth most dangerous and tobacco is ninth.

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