Hydrocodone, by itself, has been listed in Schedule II along with oxycodone, another powerful pain medicine in such pills as OxyContin, since 1971, when the Controlled Substances Act took effect. The new rule adds drugs that contain both hydrocodone and other substances such as ibuprofen or acetaminophen. For the millions of patients who rely on drugs such as Vicodin or Lortab for relief from severe pain, the new rules will sharply reduce how many pills a doctor can prescribe for them at one time. Doctors, who under schedule III could prescribe a six-month supply as a 30-day prescription with up to five refills, will now be limited to a three-month supply under schedule II. The rule also mandates that doctors must write the prescriptions in 30-day increments that can only be filled sequentially. Pain patients using the drugs will have visit their doctors every three months for a new prescription. The change also adds a new layer of regulations manufacturers and pharmacies, which must keep the drugs under tighter security and keep more extensive records.