UPDATE 1-Spectrum sells generic migraine injection stake to Par

(Adds details)

May 7 (Reuters) - Spectrum Pharmaceuticals Inc (SPPI.O) said it sold a majority of its stake in profits from a generic version of migraine injection sumatriptan to Par Pharmaceutical Inc (PRX.N) for $20 million.

This drug, originally made by British drugmaker GlaxoSmithKline (GSK.L) under the brand name Imitrex, is not core to Spectrum, it said in a news release.

Spectrum and Par are in a deal to develop and market generic drugs.

In a separate release, Par said its profit share from the drug will rise to 95 percent from 38 percent as a result of Wednesday's deal.

Annual U.S. sales of Imitrex injection are about $220 million, according to health data provider IMS Health, Par said.

Par said it can sell generic versions of the 4 mg and 6 mg starter kits and the 4 mg and 6 mg pre-filled syringe cartridges, with an expected launch date no later than Nov 2008, which is three months before the compound patent expires in Feb 2009.

Par said it also bought Spectrum's remaining interest for the right to sell the 6 mg vials. (Reporting by Varsha Tickoo in Bangalore; Editing by Jarshad Kakkrakandy)