points prior to submission of a new drug application. The other most common time is pre-NDA—right before a new drug application is submitted. ● Phase 3 studies : Phase 3 begins if Phase 2 shows evidence of effectiveness. These studies gather more information about safety and effectiveness, studying different populations and different dosages and using the drug in combination with other drugs. The number of subjects usually ranges from several hundred to about 3,000 people. ● Post-marketing study commitments : Also called Phase 4 commitments, these are studies required of or agreed to by a sponsor that are conducted after the FDA has approved a product for marketing. The FDA uses post- marketing study commitments to gather additional information about a product’s safety, efficacy, or optimal use. ● New drug application (NDA) : This is the formal step a drug sponsor takes to ask that the FDA consider approving a new drug for marketing in the United States. An NDA includes all animal and human data and analyses of the data, as well as information about how the drug behaves in the body and how it is manufactured. (U.S. Food & Drug Administration, 2018)
make sure the study is acceptable, that participants have given consent and are fully informed of their risks, and that researchers take appropriate steps to protect patients from harm. ● Phase 1 studies : These studies are usually conducted in healthy volunteers. The goal is to determine what the drug’s most frequent side effects are and often how the drug is metabolized and excreted. The number of subjects typically ranges from 20 to 80. ● Phase 2 studies : Phase 2 begins if Phase 1 studies don’t reveal unacceptable toxicity. While the emphasis in Phase 1 is on safety, the emphasis in Phase 2 is on effectiveness. This phase aims to obtain preliminary data on whether the drug works in people who have a certain disease or condition. For controlled trials, patients receiving the drug are compared with similar patients receiving a different treatment—usually an inactive substance (placebo) or a different drug. Phase 2 continues to evaluate safety and studies short-term side effects. Typically, the number of subjects in Phase 2 studies ranges from a few dozen to about 300. At the end of Phase 2, the FDA and sponsors try to come to an agreement on how to conduct the large-scale studies in Phase 3. How often the FDA meets with a sponsor varies, but this is one of two most common meeting
DRUG NOMENCLATURE
the American Medical Association. The United States Adopted Names (USAN) assigns the generic name, which may be used by any interested party. A generic drug name is not capitalized; for example, aluminum hydroxide. 3. Brand, proprietary, or trade name : Trade names are copyrighted terms selected by a manufacturer to designate a particular product. Copyright laws prevent any other person from using the name, and other laws prevent pharmacists from substituting chemically identical products for the trade name article. When there are no longer any legal restrictions on the use of a brand name, the most widely accepted and familiar name may become the official or generic name. 4. Synthesis : Synthesis is the artificial building up of a chemical compound by the union of its elements. Drugs such as epinephrine that were once available only from natural sources can now be artificially reproduced through synthesis. Other drugs such as the sulfonamides were originally created through synthesis. 5. Microorganisms : Chemical substances produced by microorganisms such as fungi and bacteria are also sources of drugs. Examples: penicillin, tetracycline, and vaccines.
Three name classifications of drugs are the chemical, or scientific name; the generic name; and the brand or trade name (Smith-Marsh, 2018): 1. Chemical (scientific) name : Drugs often have several names. When a drug is first discovered, it is given a chemical name, which describes the atomic or molecular structure of the drug. The chemical name is thus usually too complex and cumbersome for general use. Next, a shorthand version of the chemical name, or a code name (such as RU 486), is developed for easy reference among researchers. 2. Generic name : The generic or official name of a drug is assigned by its producer in collaboration with the Food and Drug Administration and Council on Drugs of
SOURCES OF DRUG PREPARATIONS
There are five main sources from which drugs are obtained: 1. Mineral : Many mineral substances found in nature are used in drugs. Examples: iodine, zinc oxide, and magnesium sulfate (Epsom salt). 2. Plant : Certain drugs are derived from vegetables and plants. Examples: digitalis, morphine, and senna pod extract. 3. Animal : The organs, tissues, and body fluids of animals (including humans) are the source of some drugs. Examples: hormones, antitoxic serums, and gamma globulin from human blood.
TYPES OF DRUG PREPARATIONS
Drugs or drug mixtures that are divided into definite doses are dosage forms. Examples of dosage forms are capsules, tablets, ampules, and cartridge units. Some dosage forms prepared for oral administration are enteric coated with a special coating that resists the action of the stomach juices but dissolves in the intestine. This helps prevent nausea, irritation of the stomach lining, or destruction of the drug. Scored tablets are marked with an indented line across the surface so that they can be broken in half when half a tablet is the dose required. Drugs prepared with flavored coatings or in flavored vehicles are exceptionally hazardous to children if left where they have access to them.
Drugs are compounded into various types of preparations, depending upon each drug’s physical characteristics, its intended purpose, and the method of administration. Some drugs are prepared in more than one form so they may be administered several ways. To give them bulk or form, drugs may be mixed with other substances that have no action or medicinal value. These substances are called vehicles . For a drug in aqueous solution, water is the vehicle; for a drug in an ointment, fatty substances, such as petrolatum or lanolin, are used as the vehicle.
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