Last Updated: 2007-09-28 17:35:19 -0400 (Reuters Health)

WASHINGTON (Reuters) – U.S. regulators said on Friday they are beginning a campaign to crack down on companies selling unapproved versions of the often-abused narcotic hydrocodone.

The U.S. Food and Drug Administration said the ingredient, legal in approved drugs like Vicodin, is now widely used and abused in unapproved versions to control coughing.

The agency said it will take enforcement action against companies marketing unapproved versions, but did not name specific ones. Companies selling the drugs for children under the age of 6 years must stop before Oct. 31, the agency said, because there is no evidence supporting its safe use in this group.

There are seven FDA-approved versions of cough suppressants containing the drug.

The effort is part of a larger FDA strategy to crack down on drugs that slip through the approval process, announced last year.