What is the required ratio of aspirin to butalbital to be exempt from controlled substance scheduling?

The ratio of aspirin to butalbital that is required to be exempt from controlled substance scheduling is specifically outlined by the Food and Drug Administration (FDA) and Drug Enforcement Administration (DEA) regulations. The correct ratio of 188 mg of aspirin to 15 mg of butalbital meets the criteria established for exemption from scheduling as it reflects the maximum allowable concentration of butalbital in combination products.

This combination is important because while butalbital is classified as a controlled substance due to its potential for abuse, when formulated with aspirin within defined limits, the combination can be considered safe for over-the-counter use. Additionally, it is key to note that if the ratio exceeds this established limit, it may result in the product being classified as a controlled substance, which would impose additional regulatory requirements for prescribing, dispensing, and record-keeping.

The other choices do not adhere to the stipulated ratio or concentrations laid out in the guidelines. They either have a higher amount of butalbital or an incorrect amount of aspirin that would not qualify for this exemption. Understanding these ratios is crucial for pharmaceutical practice, ensuring compliance with legal requirements for medications.