Which statement is true regarding Schedule III controlled substances?

The statement regarding Schedule III controlled substances that is true is the one that indicates oral prescriptions require an original prescription within 7 days. This requirement stems from federal regulations, which allow practitioners to call in prescriptions for Schedule III substances, but necessitate that a written prescription be provided within a specified timeframe to ensure proper record-keeping and monitoring.

For context, the other options illustrate different aspects of controlled substances regulation. Ordering Schedule III drugs does not require the filling out of a DEA 222 form, as that form is specifically designated for Schedule I and II substances. Also, the notion that pharmacies can fill prescriptions with only 48 hours' notice is misleading, as the rules for filling prescriptions, especially those for controlled substances, involve more stringent protocols. Lastly, the assertion that only licensed clinics can dispense methadone for pain is not entirely accurate, as there are various methods through which methadone can be prescribed and dispensed by licensed practitioners outside of a clinic setting.