Introduction about pharmacology

This chapter focuses on the fundamental principles of pharmacology. It discusses basic information, such as how drugs are named and how they’re created. It also discusses the different routes by which drugs can be administered.

Kinetics, dynamics, therapeutics
This chapter also discusses what happens when a drug enters the body. This involves three main areas:
pharmacokinetics (the absorption, distribution, metabolism, and excretion of a drug)
pharmacodynamics (the biochemical and physical effects of drugs and the mechanisms of drug actions)
pharmacotherapeutics (the use of drugs to prevent and treat diseases).

What’s in a name?

Drugs have a specific kind of nomenclature’that is, a drug can go by three different names:

• The chemical name is a scientific name that precisely describes its atomic and molecular structure.
• The generic, or nonproprietary, name is an abbreviation of the chemical name.
• The trade name (also known as the brand name or proprietary name) is selected by the drug company selling the product. Trade names are protected by copyright. The symbol ® after the trade name indicates that the name is registered by and restricted to the drug manufacturer.

To avoid confusion, it’s best to use a drug’s generic name because any one drug can have a number of trade names.

In 1962, the federal government mandated the use of official names so that only one official name would represent each drug. The official names are listed in the United States Pharmacopeia and National Formulary.

Family ties

Drugs that share similar characteristics are grouped together as a pharmacologic class (or family). beta-adrenergic blockers are an example of a pharmacologic class.

The therapeutic class groups drugs by therapeutic use. Antihypertensives are an example of a therapeutic class.

Where drugs come from

Traditionally, drugs were derived from natural sources, such as:

• plants
• animals
• minerals.

Today, however, laboratory researchers use traditional knowledge, along with chemical science, to develop synthetic drug sources. One advantage of chemically developed drugs is that they’re free from the impurities found in natural substances.

In addition, researchers and drug developers can manipulate the molecular structure of substances such as antibiotics so that a slight change in the chemical structure makes the drug effective against different organisms. The first-, second-, third-, and fourth-generation cephalosporins are an example

Old-fashioned medicine

The earliest drug concoctions from plants used everything: the leaves, roots, bulb, stem, seeds, buds, and blossoms. Subsequently, harmful substances often found their way into the mixture.

As the understanding of plants as drug sources became more sophisticated, researchers sought to isolate and intensify active components while avoiding harmful ones.

Power plant

The active components consist of several types and vary in character and effect:

• Alkaloids, the most active component in plants, react with acids to form a salt that can dissolve more readily in body fluids. The names of alkaloids and their salts usually end in “-ine.” Examples include atropine, caffeine, and nicotine.
• Glycosides are also active components found in plants. Names of glycosides usually end in “-in” such as digoxin.
• Gums constitute another group of active components. Gums give products the ability to attract and hold water. Examples include seaweed extractions and seeds with starch.
• Resins, of which the chief source is pine tree sap, commonly act as local irritants or as laxatives.
• Oils, thick and sometimes greasy liquids, are classified as volatile or fixed. Examples of volatile oils, which readily evaporate, include peppermint, spearmint, and juniper. Fixed oils, which aren’t easily evaporated, include castor oil and olive oil.

Animal magnetism

The body fluids or glands of animals can also be drug sources. The drugs obtained from animal sources include:

• hormones such as insulin
• oils and fats (usually fixed) such as cod-liver oil
• enzymes, which are produced by living cells and act as catalysts, such as pancreatin and pepsin
• vaccines, which are suspensions of killed, modified, or attenuated microorganisms.

Mineral springs

Metallic and nonmetallic minerals provide various inorganic materials not available from plants or animals. The mineral sources are used as they occur in nature or are combined with other ingredients. Examples of drugs that contain minerals are iron, iodine, and Epsom salts.

Down to DNA

Today, most drugs are produced in laboratories and can be:

• natural (from animal, plant, or mineral sources)
• synthetic.