Currently Enrolling Trials
Muse is a single-use disposable applicator containing alprostadil, a synthetic version of the naturally occurring vasodilator prostaglandin E1.
Muse is specifically indicated for the treatment of erectile dysfunction.
Muse is supplied as a single-use disposable applicator. Muse is a transurethral delivery system available in 4 dosage strengths: 125 mcg, 250 mcg, 500 mcg, and 1000 mcg. Muse should be administered as needed to achieve an erection. The onset of effect is within 5-10 minutes after administration. The duration of effect is approximately 30-60 minutes. However, the actual duration will vary from patient to patient. Each patient should be instructed by a medical professional on proper technique for administering Muse prior to self-administration. The maximum frequency of use is no more than 2 systems per 24-hour period.
Mechanism of Action
Prostaglandin E1 is a naturally occurring acidic lipid that is synthesized from fatty acid precursors by most mammalian tissues and has a variety of pharmacologic effects. Human seminal fluid is a rich source of prostaglandins, including PGE1 and PGE2, and the total concentration of prostaglandins in ejaculate has been estimated to be approximately 100-200 mcg/mL. In vitro, alprostadil (PGE1) has been shown to cause dose-dependent smooth muscle relaxation in isolated corpus cavernosum and corpus spongiosum preparations. Additionally, vasodilation has been demonstrated in isolated cavernosal artery segments that were pre-contracted with either norepinephrine or prostaglandin F2α. When alprostadil was injected into the corpus cavernosum of pigtail monkeys in vivo, dose-dependent increases in cavernosal artery blood flow were observed.
In human studies using Doppler duplex ultrasonography, intraurethral administration of 500 mcg of MUSE resulted in an increase in cavernosal artery diameter and a 5- to 10-fold increase in peak systolic flow velocities. These results suggest that intraurethral alprostadil is absorbed from the urethra, transported throughout the erectile bodies by communicating vessels between the corpus spongiosum and corpora cavernosa, and able to induce vasodilation of the targeted vascular beds.
The vasodilatory effects of alprostadil on the cavernosal arteries and the trabecular smooth muscle of the corpora cavernosa result in rapid arterial inflow and expansion of the lacunar spaces within the corpora. As the expanded corporal sinusoids are compressed against the tunica albuginea, venous outflow through subtunical vessels is impeded and penile rigidity develops. This process is referred to as the corporal veno-occlusive mechanism.
The most notable systemic effects of alprostadil are vasodilation, inhibition of platelet aggregation, and stimulation of intestinal and uterine smooth muscle. Intravenous doses of 1 to 10 micrograms per kilogram of body weight lower blood pressure in mammals by decreasing peripheral resistance. Reflex increases in cardiac output and heart rate may accompany these effects.
Adverse effects associated with the use of Muse may include, but are not limited to, the following:
pain in the penis, urethra or testes
Clinical Trial Results
The MUSE system was evaluated in 7 placebo-controlled trials of various design in over 2500 patients with a history of erectile dysfunction of various etiologies. These trials assessed erectile function in the clinic and sexual intercourse in outpatient settings. In studies of sexual performance, patients were screened in the clinic, generally using doses of 125 mcg to 1000 mcg, for a satisfactory erectile response, then sent home with the selected dose or placebo for evaluation of sexual performance. Not all patients beginning titration had a successful dose and some patients could not tolerate MUSE, principally because of penile pain, so that the success rates in the studies described below must be understood to represent response rates only in patients who were successfully titrated.
In 2 identical multicenter, double-blind, placebo-controlled, parallel-group studies, 1511 monogamous and heterosexual patients with a mean 4-year history of erectile dysfunction and at least a 3-month history of no erections adequate for sexual intercourse without medical assistance, were enrolled and began dose titration in the clinic with doses between 125 mcg and 1000 mcg. 996 patients (66%) completed dose titration, achieved an erection sufficient for intercourse, and were randomized equally to placebo or active treatment and followed during at-home treatment for up to 3 months. 874 patients and partners completed 3 months of follow-up. About 10%, 20%, 30%, and 40% of patients were titrated to 125 mcg, 250 mcg, 500 mcg, and 1000 mcg, respectively. Couples on active therapy were more likely to have at least 1 successful sexual intercourse (65% vs. 19%) than were couples on placebo. Among patients who reported successful intercourse at least once with active treatment, approximately 7 of 10 MUSE systems resulted in successful sexual intercourse. Results were similar in patients with erectile dysfunction stemming from surgery or trauma, diabetes, vascular disease, or other etiologies, and were similar in Caucasians and non-Caucasians. In administrations resulting in sexual intercourse, the duration of erections sufficient for penetration was 6 minutes on placebo and 16 minutes on active drug. Successful therapy with MUSE was associated with improvement in the quality of life measures of “emotional well-being” for patients and “relationship with partner” for both patients and their female partners.