A drug is a chemical agent, which affects human metabolism and provides cure from ailment.
Use of chemicals for a therapeutic effect is called chemotherapy.
Drugs usually interact with biological macromolecules such as carbohydrates, proteins, lipids and nucleic acids. These are called target molecules.
Drugs are designed to interact with specific targets so that they have the least chance of affecting other targets. This minimizes the side effects of the drugs.
Food additives such as preservatives, sweetening agents, flavours, antioxidants, edible colours and nutritional supplements are added to the food to make it attractive and add nutritive value. Preservatives prevent spoilage of food due to microbial growth.
Synthetic detergents are of three types: anionic, cationic and non-ionic.
Detergents with straight chain of hydrocarbons are preferred over branched chain as the latter are non-biodegradable and cause environmental pollution.