SCHAUMBURG, Ill. The Food and Drug Administration has approved a generic injected drug made by Sagent Pharmaceuticals for treating migraine attacks, Sagent said Monday.

The FDA approved Sagent’s sumatriptan succinate injection in the 6 mg per 0.5 milliliter strength. The drug is used to treat acute migraine attacks and cluster headache episodes.

Sumatriptan is a generic version of GlaxoSmithKline’s Imitrex. Injectable sumatriptan had $22 million in sales in 2009, according to IMS Health.