Self-Administered Injection Boosts Low Sex Drive in Women
Medscape 2013 Subcutaneous injection of the melanocortin receptor agonist Bremelanotide (PT-141) effectively and safely treat pre-menopausal women suffering from female sexual dysfunction, new research shows.
Self-administered at home, right before sex, both 1.25-mg and 1.75-mg SC doses decreased distress, increased arousal and desire, and enhanced the women's enjoyment of sex....
PT-141 Enhances Dopamine
"Female sexual dysfunctions, including hypo-active sexual desire or low sexual desire that causes distress, and female sexual arousal disorder are common, and currently there are no approved drug therapies for these conditions," said Dr. Clayton.
"The women in this study have a primary sexual disorder, and women who have sexual dysfunction because they are depressed or on antidepressant therapy were excluded from the trial."
As a melanocortin receptor agonist, bremelanotide pt141 enhances dopamine, which excites or enhances sexual functioning, Dr. Clayton explained.The new study included 327 women with hypoactive sexual desire or female sexual arousal disorder, or both, for at least 6 months, as diagnosed by clinician. All women were in a stable relationship and were willing to be sexually active. They were randomly assigned in a double-blind fashion to placebo or bremelanotide 0.75, 1.25, or 1.75 mg, which was given at 2 clinic visits a week apart. This was followed by 12 weeks of at-home subcutaneous injections.
The syringes were pre-filled, and the women were instructed to self-inject 45 minutes prior to sexual activity and to use only 1 dose per day and no more than 16 doses during a 4-week period. The main outcome was the number of satisfying sexual events.
"They still could get aroused and even have an orgasm, but they still might not feel connected or feel satisfied with the whole outcome. That is why we wanted to use this satisfying sexual events, or SSE, measure, which looks at how many times the woman had sex and how many times it was satisfying," she added.
PT-141 is Well Tolerated
The study also looked at changes in the Female Sexual Function Index (FSFI) and the Female Sexual Distress Scale–Desire/Arousal/Orgasm (FSDS-DAO).Treatment with bremelanotide resulted in improvement in all 3 outcome measures, with the 1.75-mg dose resulting in the greatest improvements, Dr. Clayton said.
In keeping with the linear dose response curve, women who were randomly assigned to bremelanotide 1.25 mg showed a mean increase in SSEs of 0.7 (1.8,P = .0807 vs placebo), and those who received the 1.75-mg dose showed a mean increase in SSEs of 0.8 (2.9, P = .0215 vs placebo).The FFSI score similarly increased with bremelanotide.The mean change in FSFI total score was 1.88 (5.92) for placebo vs 2.75 (5.70) for 1.25-mg (P = .279) and 4.36 (5.58) for the 1.75-mg dose (P = .0021).Distress about sexual function also decreased. The mean change in the FSDS-DAO total score was -6.8 (13.6) with placebo, vs -9.2 (10. for 1.25 mg (P = .0508) and -13.1 (12.9) for 1.75 mg (P = .0005).
The peptide-drug was "very well tolerated," said Dr. Clayton.
"We looked at blood pressure very intensely because there used to be an nasal-spray product that seemed to have some erratic absorption and therefore elevated blood pressures. But this is now a subcutaneous injection on demand, and it does not look as if there will be any issues about this going forward.
"Nausea was the most common side effect, but this occurred early after the injection, was mild, and stopped with continued use. Other side effects were flushing and headache.