Most Common Drug Classifications

Variety of Pills
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While there are thousands of different drugs, all marketed medications fall under one or more of the first tier of the American Hospital Formulary Service (AHFS) Pharmacologic-Therapeutic Classification System. The classification was developed and is maintained by the American Society of Health-System Pharmacists (ASHP), a national association of pharmacists.

AHFS Classes

The classifications include the following:

  • Antihistamine Drugs include the prescription drugs Clarinex and Xyzal and OTC medicines Allegra, Benadryl, Claritin, Chlor-Trimeton, Dimetane, Zyrtec and Tavist.
  • Anti-infective Agents include penicillins and anti-virals
  • Antineoplastic Agents
  • Autonomic Drugs
  • Blood Derivatives
  • Blood Formation, Coagulation, and Thrombosis Agents
  • Cardiovascular Drugs include digoxin, acebutolol, propranolol, and lisinopril
  • Cellular Therapy
  • Central Nervous System (CNS) Agents include stimulants and depressants
  • Contraceptives (foams, devices)
  • Dental Agents
  • Diagnostic Agents
  • Disinfectants (for agents used on objects other than skin)
  • Electrolytic, Caloric, and Water Balance
  • Enzymes
  • Respiratory Tract Agents
  • Eye, Ear, Nose, and Throat (EENT) Preparations
  • Gastrointestinal Drugs include rabeprazole sodium, nitazoxanide, bevacizumab, and nizatidine, an OTC anti-ulcer treatment
  • Gold Compounds
  • Heavy Metal Antagonists
  • Hormones and Synthetic Substitutes
  • Local Anesthetics
  • Oxytocics
  • Radioactive Agents
  • Serums, Toxoids, and Vaccines
  • Skin and Mucous Membrane Agents
  • Smooth Muscle Relaxants include cyclobenzaprine and carisoprodol
  • Vitamins
  • Miscellaneous Therapeutic Agents
  • Devices
  • Pharmaceutical Aids

The full classification system is updated annually and published in AHFS Drug Information.

Legal Classification of Drugs

In the United States, the legal classification of drugs was initiated under the Controlled Substances Act of 1970 and its re-passage in 1990. Drugs fall within different schedules based on their potential for abuse. Some of the drugs are available only by prescription and some are available over-the-counter (OTC).

When Congress passed the Controlled Substances Act it acknowledged in the statute that many drugs have a legitimate medical purpose and are "necessary to maintain the health and general welfare of the American people." However, lawmakers also recognized the detrimental effect that illegal importation, manufacturing and the improper use of certain drugs were having on the population. The Controlled Substances Act was designed "to establish effective control over international and domestic traffic in controlled substances," according to the Act.

  • Schedule 1 drugs have high potential for abuse, are not recognized for medical use and pose a safety risk. These drugs include heroin, lysergic acid diethylamide (LSD), MDMA (ecstasy), marijuana, and methaqualone.
  • Schedule 2 drugs have a high potential for abuse, have medical utility, and a high risk for dependency (addiction). Drugs categorized as Schedule 2 include opium, morphine, coca, cocaine, methadone, and methamphetamine.
  • Schedule 3 drugs have a lower potential for abuse, have medical utility, and pose a moderate risk for dependency. Amphetamine, barbiturate, Valium, Xanax, anabolic steroids, and codeine are Schedule 3 drugs.
  • Schedule 4 drugs have limited potential for abuse, have high medical utility, and limited risk for dependency. This category includes chloral hydrate, meprobamate, paraldehyde, and phenobarbital.
  • Schedule 5 drugs pose minor problems and are generally preparations of drugs containing limited amounts of Schedule 1 through 4 drugs. Cough medicines with codeine are an example of Schedule 5 drugs.

The schedule of the drug generally determines the penalties for the illegal manufacturing and distribution of controlled substances. The Controlled Substances Act has been amended by Congress since its initial passage in 1970, and states have also recently begun challenging the penalty for possession of certain drugs, most notably marijuana.

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