C-II drugs are prescription drugs which have a high risk of abuse and/or addiction; two examples would be morphine and oxycodone.
The US Drug Enforcement Agency has placed federal limits on various aspects of C-II prescriptions. A prescription for a C-II listed substance must be in written form and hand signed except in certain specific circumstances. These prescriptions cannot be refilled. As far as time limits, the DEA's website (link below) says:
"There is no federal time limit within which a schedule II prescription must be filled after being signed by the practitioner. However, the pharmacist must determine that the prescription is still needed by the patient."
States may issue more stringent regulations than the federal government on such issues, and in this case many of them have done so. For example, Nevada limits the filling of a C-II prescription to 14 days from the date of issue, but in California C-II prescriptions are good for six months after the date of issue. Military pharmacies require the prescription to be less than 30 days old, as does the state of Massachusetts. In Illinois the time limit is 90 days.