Federal regulators have approved a new generic cough medicine made by Cornerstone Therapeutics in Cary.

The drug is a generic version of an antihistamine combination now sold under the Tussionex Pennkinetic brand. It is to relieve cough and respiratory symptoms associated with colds and allergies in people 6 and older.

The generic was developed in collaboration with Coating Place and Neos Therapeutics. It will be marketed through Cornerstone's generics subsidiary Aristos Pharmaceuticals. Neos will manufacture the drug.

Cornerstone is a speciality pharma that acquires, develops and commercializes respiratory medicine used in hospitals.

In a press release, Cornerstone's CEO Craig A. Collard said the drug, CRTX 067, will provide the company with growth opportunities given the demand for such products.

Total prescriptions for Tussionex and related generics were 2.59 million in 2011, up 2 percent from 2010, according to IMS Health, a N.J.-based research company that covers the pharmaceutical industry.