WASHINGTON (Reuters Health) May 31 - Palatin Technologies reported on Thursday results from a phase I study of its erectile dysfunction (ED) drug PT-141 that suggest that the nasally inhaled agent begins to take effect within 5 minutes and exhibits no serious side effects.
Palatin's double-blind, placebo-based dose-escalation trial showed no significant changes in patients' blood pressure or heart or respiratory rates, the company said. Nor did the study's 56 healthy volunteers experience any nausea, vomiting or syncope, it said.
It also appeared from the findings that PT-141's delivery permits the drug to reach maximum levels in the blood in about 30 minutes, Palatin said.
Although PT-141's efficacy will be evaluated in later trials, "a significant number of erections were observed at one dose level," the company said. Palatin said it hopes to confirm those preliminary findings in its phase II study, set to begin later this year.
PT-141 is a peptide analog of (alpha)-MSH ([alpha]-melanocyte-stimulating hormone), which stimulates the cell receptors that influence a variety of behaviors that include sexual arousal.
The firm said it also anticipates to launch a second phase II trial in the fourth quarter to evaluate PT-141 in treating female sexual dysfunction.
According to Palatin CFO Stephen Wills, the company eventually hopes to demonstrate that PT-141 is superior to Pfizer's blockbuster ED treatment Viagra (sildenafil).
"We believe we will be a very good competitor [of Pfizer] because [PT-141] works on the arousal centers in the brain," he told Reuters Health. In contrast, he noted, Viagra users must "get [the arousal process] started," after which Viagra blocks the "blood flow reducer" in the body.
Willis added that demonstrating superiority to Viagra would place the company in a strong competitive position.
The only other ED agent in the pipeline with a similar mechanism of action is TAP Pharmaceutical's Uprima (apomorphine), which was linked last year to several cases of syncope, which caused the withdrawal of its approval application, he noted.
Other treatments under investigation, including Eli Lilly's and ICOS Corp.'s Cialis (IC351), are similar to Viagra, meaning that an adequate amount of blood must first flow to the penis for an erection to be maintained, he added.
Willis also observed that the Palatin drug was well tolerated at all doses, and that the investigators did not identify a maximum dose.
ED affects more than 30 million men in the US, representing a market opportunity of approximately $2.0 billion, Palatin said in a news release. The company also noted that in at least one male-aging study recently completed, more than 50% of men aged 40 to 60 years reported episodes of ED.
At market close,
shares in Princeton, New Jersey-based Palatin were up 0.23 to 5.87 on the
American Stock Exchange after a volatile day of trading in which the volume
of shares traded were more than six times the company's daily average.
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