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| Drugs are substances that change chemical reactions in the body. Medical drugs relieve disease and illness, and are extensively tested before being used. Recreational drugs such as alcohol and tobacco are taken by people because they like the effects they have on their bodies, but they may be addictive. Cannabis and heroin are illegal recreational drugs that are very addictive. | New medical drugs have to be tested to ensure that they work, and are safe, before they can be prescribed. There are three main stages of testing: The drugs are tested using computer models and human cells grown in the laboratory. Many substances fail this test because they damage cells or do not seem to work. Drugs that pass the first stage are tested on animals. In the UK, new medicines have to undergo these tests, but it is illegal to test cosmetics and tobacco products on animals. A typical test involves giving a known amount of the substance to the animals, then monitoring them carefully for any side-effects. Drugs that have passed animal tests are used in clinical trials. They are tested on healthy volunteers to check they are safe. Very low doses of the drug are given to begin with. If there are no problems, further clinical trials are done to find the optimum dose for the drug. |
| Clinical trials are not without risk. Sometimes severe and unexpected side effects occur. Most substances do not pass all of the tests and trials, so drug development is expensive and takes a long time. | Double blind trials It is important to be certain that a drug really does have positive effects, rather than people feeling better simply because they expect to feel better if they take a medicine. This is called the placebo effect. |
| Double blind trials aim to minimise the placebo effect. Some patients are given the drug while others are given a placebo. A placebo is designed to appear exactly the same as the drug itself, but it does not actually contain any of the drug. The doctors and patients are not told who have received the drug and who have received the placebo until the trial is over. | Thalidomide is a medical drug that caused unexpected and serious damage to unborn babies in the 1950s and 1960s. Thalidomide 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. |
| 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. Drug testing was also made more rigorous than before. | 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. |
| Drugs change chemical processes in the body. People may become dependent on the drug or addicted to it, and may suffer withdrawal symptoms if they stop taking the drug. Alcohol and nicotine (found in tobacco) are legal recreational drugs. However, misuse of them can cause health problems. | The alcohol in alcoholic drinks such as wines, beer and spirits is ethanol, which is a depressant, meaning 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. Alcohol is addictive. Long-term effects of alcohol include damage to the liver and brain, and it is often the cause of weight gain. Women who are pregnant are warned not to drink alcohol or at least to limit their intake. |
| About 114,000 people die every year as a result of smoking-related illnesses. All cigarettes sold now carry a prominent health warning. Nicotine is the addictive substance in tobacco smoke. It reaches the brain within 20 seconds and creates a dependency so that smokers become addicted. Smoking increases the risks of: heart disease and strokes miscarriage, premature birth and low birth weight lung cancer, mouth cancer and throat cancer. | Illegal drugs include prescription drugs that have been dangerously modified and substances that are banned by law. Ecstasy, cannabis and heroin are illegal recreational drugs. Using them can cause health problems. |
| Heroin and cocaine are very addictive. Like ecstasy, they can damage the heart and circulatory system. Cannabis smoke contains chemicals that cause mental illness in some people. | Recreational drugs, both legal and illegal, may also damage our health indirectly. For example, buying the drugs reduces the amount of money available to buy food, and may place users in dangerous situations. Injecting a drug using 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. Many more people use legal drugs, both prescribed and non-prescribed, than use illegal drugs. This means that the overall impact of health from legal drugs is greater than the overall impact of illegal drugs. |
| 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. | Athletes are often under great pressure to perform well. Some drugs are capable of artificially improving their performance; these include: stimulants – these boost heart rate and other body functions anabolic steroids – these stimulate the growth of muscles. |
| Some of these drugs are banned by law. Others are legally available on prescription or even in some medicines available from the pharmacy. However, the use of performance enhancing drugs is widely seen as unfair. They may also damage the athlete’s body. Sporting regulations ban the use of performance enhancing drugs, and athletes are regularly tested to make sure that they are not using them. | Biology 1- The uses and testing of drugs |
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