__________ is a term referring to a diminishing drug effect such that more is required to obtain the original effect.

• A. Addiction
• B. Tolerance
• C. Withdrawal
• D. Abuse

Answer: (B)

A diminished response to a drug after repeated use, requiring a larger dose to achieve the same effect, is called tolerance. This happens as the body adapts through pharmacodynamic changes (receptors becoming less sensitive or fewer in number) or pharmacokinetic changes (faster metabolism or clearance). Because the body has adjusted, more of the drug is needed to reach the original level of effect.

This concept is distinct from the other terms: addiction involves compulsive use despite harm, withdrawal refers to symptoms that occur when stopping the drug, and abuse means improper or harmful use. The scenario described fits tolerance, where the same amount no longer yields the same effect and a bigger dose is sought.