Medicines (medicinal drugs)
If you cut yourself you clean the wound with water and put some antiseptic cream on it. If you have stomach ache you may ask for a seltzer tablet. If you have a headache you may ask for an aspirin. These are just three examples of when you may use medicines. But what are medicines and how do they work?

Very simply, a medicine is a substance you take to keep you well. If you are eating a balanced diet, taking exercise and getting enough sleep you may have little need for medicines. Sometimes, however, something may go wrong and the correct use of a medicine helps you recover quickly. If you look on the side of a tube of antiseptic cream you may see the names of chemicals that seem impossible to pronounce. These chemicals help defend your body against harmful bacteria. Our world is full of bacteria and many land on the skin. A healthy skin can keep bacteria out of the body but when the skin is damaged, bacteria are poised to attack. The chemicals in the antiseptic kill the bacteria and snuff out their attack almost before they have begun.

The stomach is the place where the protein in your food begins to be digested. There is a special chemical that the stomach produces which is called an enzyme. It is the substance that breaks down protein but it needs help. The stomach provides this help by producing acid. Inside the warm, churning stomach, the enzymes and acids break down the proteins in meat, fish, eggs and cheese. Sometimes the stomach produces too much acid. When this happens, the acid may splash up into the throat and cause indigestion or heartburn. A seltzer tablet contains a chemical, which takes away the power of the acid. This process is called neutralisation and the indigestion goes away.

Headaches may have many causes but the pain is due to the action of the nerves. Nearly two and a half thousand years ago a Greek doctor called Hippocrates used willow bark to treat pain. In the willow bark is a chemical called salicylic acid. This is the pain-killing substance in the bark but it also had a side effect. It irritated the lining of the stomach. Just over a hundred years ago a scientist called Felix Hoffman made a discovery. He found that he could make a similar substance to the painkiller in willow bark but this substance had less powerful side effects. This new substance was aspirin. Today it is very widely used to reduce many different kinds of pain.

The three medicines mentioned so far may be used with care by almost everyone but some medicines are developed to help certain people in special ways. For example some people suffer from asthma attacks. When the attack occurs muscles around the airways in the lungs become tense. They squeeze on the airways and make them narrower. This makes it more difficult to breathe. When a person suffers an asthma attack they can inhale a substance called salbutamol. It makes the muscles around the airways relax. The airways then become wider and the person finds it easier to breathe.

Scientists are always searching for new medicines to improve people's lives. Many scientists are looking at plants again, just as doctors and healers did in the past. They are studying the rainforest plants and making many new discoveries. They are having to work fast because rainforests are being destroyed at such an alarming rate. If the rainforests can be saved then more medicines may be found that can treat illnesses more effectively than some of the medicines we use today and more lives may be improved or even saved.

Why should you not exceed the stated dose of a medicine?
The dosage of the medicine has been worked out to provide the maximum healing power with the least side effects. If the dosage is increased the power of the side effects may be increased and this may severely damage health or even prove fatal.

What is diabetes and can it be controlled by a medicine?
Diabetes is a disease in which the body cannot store sugar. It can be controlled by taking a substance called insulin. The body uses sugar as a fuel. It can take energy quickly from the sugar to provide the power for all life processes. In a healthy body the blood carries a certain amount of sugar so all parts of the body can get the energy they need. After a meal the blood is flooded with sugar from the food and a chemical called insulin makes the liver soak up the sugar and store it. This stored sugar is then slowly released to top up the amount of sugar in the blood. A person who suffers from diabetes cannot make enough insulin to store the sugar so they take insulin as a medicine to help them.

Why is storing sugar so important?
If the sugar is not stored it is filtered out of the blood in the kidneys and excreted from the body in the urine. This means that the body loses a great amount of fuel and the person develops sugar diabetes. Some of the symptoms of this disease are tiredness, loss of weight and an increase in urine production.

Why must insulin be injected and not taken as a pill?
Insulin is a protein. If it was taken as a pill it would enter the stomach and be digested before it reached the blood and could do its work. By being injected into the body it enters the blood straight away and avoids the digestive powers of the stomach.

Are antibiotics medicines?
Yes, they are. They are used to kill bacteria which invade the body. An antibiotic might stop a bacterium growing or might enter its body and kill it. Antibiotics do not work against viruses.

Are there any medicines that work against viruses?
There are a few anti-viral drugs. A virus causes disease by entering the body cells and stealing materials in order to reproduce. An anti-viral drug stops the virus getting hold of the chemicals it needs to breed, so the infection is stopped.