What characteristic distinguishes effervescent tablets from regular tablets?

Effervescent tablets are distinct from regular tablets primarily because they contain acids and bases that react when they come into contact with water, resulting in the production of carbon dioxide gas. This reaction creates fizz or effervescence, which is a key characteristic of these tablets. The fizzing helps to dissolve the tablet more quickly in a liquid, allowing for faster absorption of the active ingredients once ingested, enhancing convenience and effectiveness for the patient.

In contrast, the other options do not accurately describe effervescent tablets. While some slow-release formulations exist, effervescent tablets are not specially designed for slow release; rather, they are intended for quick dissolution. Additionally, effervescent tablets actually require water for their intended use, as they need to be dissolved in liquid to activate the effervescent effect. Lastly, while they may contain powders as part of their formulation, the primary distinguishing feature of effervescent tablets is indeed their fizzing behavior in water, rather than their composition.