UPDATE 1-Forest constipation drug meets goal in studies

(Adds study details)

NEW YORK, March 4 (Reuters) - Forest Laboratories Inc (FRX.N: Quote, Profile, Research) said on Tuesday its experimental drug for chronic constipation met the primary goal of a pair of mid-stage studies, according to an analysis of preliminary results.

Based on available results, Forest said it plans to move the drug, linaclotide, into phase 3 studies for both chronic constipation and irritable bowel syndrome with constipation in the second half of this year.

Phase 3 is typically the final stage of human testing prior to seeing approval for an experimental medicine.

The once-daily drug was tested at four doses for changes in frequency of weekly spontaneous bowel movement (SBM).

In the four-week chronic constipation study, the increase in SBM from taking linaclotide was statistically significant at all but the lowest 75 microgram dose. It was also tested in 150 mcg, 300 mcg, and 600 mcg doses.

In the 12-week irritable bowel syndrome study, patients experienced a significant increase in weekly complete SBM frequency at all but the 150 mcg dose, Forest said.

Linaclotide, which is being developed along with Microbia Inc, was well tolerated at all doses with no serious adverse events, the companies said.

The most common adverse event was diarrhea, incidents of which rose along with the dose taken. (Reporting by Bill Berkrot; Editing by Andre Grenon and Braden Reddall)