Allison Owens, age 13, of Hattesburg, Miss., for her question:

WHEN WERE MEDICAL DRUGS FIRST USED?

A drug is a substance that is used as a medicine. The mixing of drugs to relieve pain is an old art. The first doctors were often priests, teachers or philosophers who had learned of the healing power vf certain plant products.

Ancient Greeks used plant products as drugs and so did the Romans.

In olden days medicine men picked herbs and used them as medicines. Them after centuries of experimentation, along came the apothecary who read formulas from thick volumes and rolled pills by hand.

Many people believe that the word "drug" means a habit forming substance that is taken to produce a feeling of well being, to relieve pain or to produce sleep. There are indeed certain dugs that are habit forming. These drugs are called narcotics.

Most medicines today are purified and simple. Doctors know the chemical nature of each drug and how it affects the different parts of the body.

It is most important that all people understand that certain drugs are potentially dangerous and should be taken only when prescribed by a doctor.

New and better medicines are regularly being round that are more effective against illness than were the old ones. Yet some of the plants used as drugs hundreds of years ago are still being used effectively today.

Many drugs are called "extracts" because they are taken, or extracted, from another substance. quinine is made from the bark of the cinchona tree. Digitalis is made from the purple foxglove flower and is used as a heart stimulant. Atropine, made from belladonna, is used to dilate the pupil of the eye.

Many drugs come from minerals and their compounds: iron salts, bromides, ammonium chloride, potassium iodide and Epsom salt.

Other drugs come from the organs of animals. Thyroxine comes from the thyroid while a number of other drugs come from the pituitary gland.

Another class of drugs are the vaccines, toxoids and antitoxins. Vaccines and toxoids are useful in preventing disease.

A synthetic drug is made from chemicals instead of plants or other natural sources. More and more of our useful drugs today are synthetic. They are made in laboratories by research chemists.

New drugs have to be carefully tested before they are used by humans. The sulfa drugs were first tried on mice in laboratory tests. Since then, sulfa drugs have saved thousands of human lives from pneumonia and other bacterial diseases.

Other synthetic drugs are antihistamines, aspirin, a large number of antiseptics and most sedatives. Cortisone, which is found naturally in the adrenal glands, and several other naturally occuring drugs are also made now by synthetic methods.

Antibiotics date from the mid 1900s. Certain molds and soil bacteria produce chemicals that stop the growth of many disease causing bacteria. Penicillin and streptomycin are two of our more important antibiotics.