Updated from 12:25 p.m. EDTOn a flat to positive day for health stocks Wednesday, several companies declared breakups, acquisitions, patent rulings and approvals. RNAi therapeutic company Alnylam ( ALNY) and Merck ( MRK) said Wednesday that they mutually agreed to terminate their July 2006 amended-and-restated collaboration agreement. Merck agreed in October 2006 to pay $1.1 billion for Sirna (siRNA) Therapeutics, an Alnylam competitor that develops RNAi technology. Alnylam said Wednesday that it rescinded all grants of its intellectual property related to current and future Merck development programs, including former co-development programs. The company maintained guidance that it will have $435 million in cash by the end of the year. Alnylam shares closed up $1.28, or 4.1%, to $32.40. Merck closed up 99 cents, or 2%, to $51.56. Not everyone was breaking up. Allergan ( AGN) announced a $370 million all-cash deal to acquire privately held Esprit Pharma, which markets Sanctura for overactive bladder. The Food and Drug Administration recently granted approval for an extended-release version of the drug. Allergan shares rose 82 cents, or 1.3%, to close at $63.03. Related to that acquisition, Indevus Pharmaceuticals ( IDEV), which licensed Sanctura to Esprit, said Wednesday that it amended its license, commercialization and supply agreement with Allergan. Indevus shares slid 43 cents, or 5.9%, to close at $6.85. Elsewhere, biotechnology company Neuralstem ( CUR) said the U.S. Patent and Trademark Office ruled in its favor in a patent dispute with StemCells ( STEM).