Ch 16Chemistry in Everyday Life — Class 12 Chemistry, concept-first.

A drug is a small organic chemical, typically in the molecular-mass range of roughly 100 to 500 atomic mass units, that is capable of interacting with a large biological macromolecule inside the body…

Because a single drug molecule can be described from several different chemical and biological angles, there is no single "correct" classification scheme - each scheme highlights a different aspect us…

Classification by pharmacological effect sorts drugs according to the overall physiological outcome they produce in the patient, irrespective of their chemical structure or the precise biochemical ste…

Classification by drug action sorts drugs according to the specific biochemical process or molecular event that the drug interferes with, which is a narrower and more mechanistic criterion than overal…

Classification by chemical structure groups together drugs that share a common structural skeleton or core framework, because molecules built on the same skeleton very often show similar pharmacologic…

Classification by molecular target groups drugs by the specific biomolecule they physically bind to inside the body, and is considered by medicinal chemists to be the most useful and mechanistically i…

Large biological macromolecules perform a wide variety of roles inside a living organism, and a drug typically works by interacting with one of these roles:

Enzymes are one of the two drug-target classes developed in detail in this chapter. Their role as a drug target is examined from two complementary angles, covered in the two sub-sections that follow:…

An enzyme's catalytic power depends on a specific three-dimensional pocket on its surface called the active site, into which the substrate molecule fits.

A drug can interfere with an enzyme's activity by acting as an inhibitor, and there are two chemically distinct ways this can happen:

Receptors are proteins that form the core of the body's chemical communication system. Most receptor proteins sit embedded within the cell membrane, with only a small extracellular portion - carrying…

Having established how drugs interact chemically with enzymes and receptors in general terms, the chapter now turns to the therapeutic action of several specific, medically important classes of drugs…

Excessive production of acid in the stomach causes irritation and pain, and in severe, prolonged cases can progress to ulcers.

Histamine is a chemically potent signalling molecule with several physiological effects: it is a powerful vasodilator (it widens blood vessels), it contracts smooth muscle in the bronchi (airways) and…

Neurologically active drugs are a broad class of substances that act by affecting the mechanism by which a message is transferred from a nerve cell to its receptor.

Tranquilizers are chemical compounds used in the treatment of stress and of mental illness ranging from mild to severe.

Analgesics are drugs that reduce or abolish the sensation of pain, without causing loss of consciousness, mental confusion, loss of coordination, paralysis, or any other disturbance of the nervous sys…

Antimicrobial drugs destroy, prevent the growth of, or inhibit the pathogenic action of microbes, with the drug's classification depending on which type of organism it selectively targets:

Definition. An antibiotic is a substance that, at low concentration, inhibits the growth of - or destroys - microorganisms by intervening in their metabolic processes.

Antiseptics and disinfectants both function chemically to kill microorganisms or arrest their growth, but the two terms are distinguished by where the substance is applied, not by a difference in chem…

The dramatic gains in life expectancy brought about by the antibiotic revolution led to accelerated population growth, which in turn placed added pressure on food supply, environmental resources and e…

Chemical substances are deliberately added to food for three broad purposes: to preserve it against spoilage, to enhance its appeal (colour, flavour, texture), and, in a smaller number of cases, to ge…

Natural sweeteners such as sucrose contribute directly to calorie intake, which has driven the development of artificial sweeteners - compounds that provide a sweet taste while adding little or no cal…

Food preservatives are substances added to food specifically to prevent spoilage by inhibiting the growth of microorganisms within it.

Antioxidants in food are additives that help preserve food by chemically retarding the action of atmospheric oxygen on it, and different antioxidants achieve this protective effect through several gen…

Cleansing agents, taken in the broad sense, fall into two chemical families: soaps and synthetic detergents.

Chemical identity. Soaps are the sodium or potassium salts of long-chain fatty acids, such as stearic, oleic, or palmitic acid.

Synthetic detergents share all the practical cleansing properties of soap, yet contain no true soap in their formulation at all.