Which of the following is NOT listed as a basis for categorizing drugs?

• A. The physiological effect on the CNS
• B. The observable signs they produce
• C. The route of administration
• D. The geographic origin of the drug

Answer: (D)

Drug categorization is usually based on how a substance affects the body and how it’s used, not where it comes from. The physiological effect on the CNS is a primary basis because drugs are grouped by whether they depress, stimulate, or otherwise alter brain function, which informs their therapeutic uses and risks. The observable signs they produce matter because the outward effects—such as changes in mood, behavior, or physical functioning—help identify and classify substances in clinical and forensic settings. The route of administration is another basis because it shapes how quickly effects appear and how long they last, influencing practical use and control considerations. Geographic origin, while interesting, doesn’t determine a drug’s pharmacological action or typical effects, so it isn’t used as a basis for categorizing drugs.