By Bill Berkrot
(Reuters) - A drug meant to boost the libido of pre-menopausal women distressed by lack of sexual desire met the main goals of a pair of late stage clinical trials, according to initial results released on Tuesday by its developer, Palatin Technologies Inc <PTN.A>, and its shares rose 66 percent.
Palatin said the experimental drug, bremelanotide, demonstrated statistically significant improvement versus placebo on scales measuring levels of desire and distress in 24-week studies of more than 1,200 women diagnosed with hypoactive sexual desire disorder (HSDD).
"The distress component of HSDD reflects the profound negative impact that this condition can have on women's' self-image, relationships and quality of life well outside the bedroom," Sheryl Kingsberg, one of the study's investigators, said in a statement.
"In the Phase 3 trials we saw significant reduction in distress with use of bremelanotide," added Kingsberg, a professor of reproductive biology at Case Western Reserve University School of Medicine in Ohio.
Shares of tiny Palatin rose to 80 cents in after hours trading from their close at 48 cents.
The drug was well tolerated with no new safety issues identified, Palatin said. The most frequent side effect was nausea, which was generally mild.
While drugs attempting to address this disorder are often referred to as "female Viagra," Palatin's is more like Viagra in that it is designed to be taken as needed in anticipation of sexual activity, rather than every day. However, it is not a pill but administered subcutaneously via autoinjector.
The drug is a synthetic peptide analog that mimics a naturally occurring hormone.
Palatin expects to file with regulators seeking U.S. approval for bremelanotide in the second half of 2017.
If approved, it would compete with the controversial Addyi, which was approved in August under intense pressure from patient advocacy groups and is sold by Valeant Pharmaceuticals International.
Addyi, which has sold poorly, carries a boxed warning saying it can cause fainting and extremely low blood pressure and that it should not be used with alcohol.
(Reporting by Bill Berkrot; Editing by Steve Orlofsky)