A novel emergency contraceptive has received US Food and Drug Administration (FDA) approval and is set to hit US stores later in 2010.

The contraceptive, known as ella (ulipristal acetate), will be available as a prescription-only emergency contraceptive indicated for use within 120 hours of unprotected intercourse or suspected contraceptive failure.

The drug, developed by HRA Pharma, will be marketed in the US by Watson pharmaceuticals.

The FDA approval was based on two Phase III studies, which showed that ella significantly reduced the risk of pregnancy in women who used it after unprotected intercourse.

The drug works using a progesterone agonist/antagonist that inhibits follicular rupture when taken just before ovulation is due.