Which of the following medications is NOT controlled?

Spironolactone is the correct choice because it is not classified as a controlled substance. Controlled substances are drugs that are regulated by law due to their potential for abuse or dependency. Soma (carisoprodol) and diazepam are both controlled substances due to their central nervous system depressant effects and potential for misuse. Risperidone, an antipsychotic, is also categorized as a controlled substance in several jurisdictions due to its psychiatric applications.

In contrast, spironolactone is a potassium-sparing diuretic primarily used to treat conditions such as heart failure, hypertension, and certain types of edema. It does not possess the same abuse potential or addictive qualities as the other medications listed, which is why it is not controlled. This distinction is essential in pharmacy practice, as it informs healthcare providers about the prescribing, dispensing, and monitoring requirements associated with different medications.