TherapeuticsMD Inc said a late-stage study of its experimental drug to treat vaginal pain met the main goal in a late-stage study, sending the company's shares up 53 percent in extended trading.

The company said all three doses of the experimental drug, TX-004HR, reduced vaginal pain during intercourse in women who had undergone menopause.

Vaginal pain, clinically called dyspareunia, is one of the biggest symptoms of vulvar and vaginal atrophy, a common and underreported condition associated with decreased estrogen in post-menopausal women.

The three doses of the drug also increased the number of certain kinds of cells in the vagina, TherapeuticsMD said.

The company said there were no safety concerns associated with the gel.

TherapeuticsMD, which is conducting complete safety and efficacy data from the study, said it expected to file for marketing application in the first half of 2016.

The company's shares closed down 5 percent in regular trading on Monday. They were up 53 percent at $9.95 after the bell.