PT 141

Overview

PT-141, also known as bremelanotide, is a modified synthetic derivative of alpha-melanocyte-stimulating hormone (α-MSH), a peptide of the melanocortin family that regulates skin pigmentation, feeding behavior, and sexual activity, among its other functions.

As an analogue of α-MSH, PT-141 acts on the melanocortin receptors (MCRs), which are found predominantly in the skin and central nervous system and cause an increase in pigmentation by activating melanocytes. However, MCRs are also associated with effects on sexual desire and appetite. PT-141 strongly engages MC1R, MC3R, and MC4R, the latter of which plays a role in modulating sexual desire.

One of the primary benefits of PT-141 is its ability to stimulate the melanocortin receptors in the brain, leading to increased sexual arousal and desire. By targeting these receptors, PT-141 directly influences the central nervous system, promoting sexual desire and reducing performance anxiety. This makes PT-141 an excellent option for individuals who are dealing with low libido or psychological factors that impact sexual performance.

Following a subcutaneous injection or nasal atomisation of PT-141, maximal effects occur with a range of 30 minutes to one hour. In the realm of male sexual desire, this translates to a virtually on-demand erection.

Treatment of Erectile dysfunction

While PT-141 is not indicated to treat erectile dysfunction (ED), several small-scale studies have found that it may be beneficial to male patients with ED who do not respond to sildenafil (Viagra).

A 2003 phase 1 randomized double-blind placebo-controlled trial involving 24 healthy male subjects without erectile dysfunction found that test subjects who received intranasal doses of PT-141 (4 to 20 mg) experienced “significantly increased duration of rigid erections of 140 minutes compared to 22 minutes in the placebo group”.

A 2004 study involving fewer than 400 patients found that doses of 1mg of PT-141 (bremelanotide) could produce a statistically significant “erectile response”. The safety and efficacy of PT-141 in test subjects with mild to moderate ED were investigated in a phase II study. Results showed a 3-fold increase in erectile activity following 2mg intranasal administration of PT-141.

A 2008 study involving intranasal bremelanotide spray found that it could help men achieve an erection suitable for penetrative sex when administered 45 minutes prior to intercourse [9].

These findings suggest that PT-141 may act as an alternative ED treatment for subjects who do not respond to sildenafil, a potentiality that merits further research. 

PT-141 Peptide and Arousal

The potential activation of the MC4R by PT-141 may also upregulate the production of vasodilators like nitric oxide (NO) in penile tissues, leading to improved erection potential, as suggested by research. The peptide is posited to be a metabolite of Melanotan-2 (MT-II), and both appear to activate the same receptors. For example, it has been posited that melanocortin agonists might lead to concentration-related increases in cavernosal pressure.

The role of the NO-cyclic GMP-dependent pathway in relation to the melanocortin agonists-induced increases in cavernosal pressure. This was done by performing a bilateral transection of the pudendal nerves and inhibiting NO synthase using L-NAME. The results indicate that either removing the pudendal nerves or pretreating with L-NAME may negate the increases in intracavernosal pressure that melanocortin agonists likely induced in the anesthetized murine models. From the gathered data, it was tentatively inferred that the activation of central melanocortin receptors by melanocortin agonists might lead to an increase in cavernosal pressure, probably achieved through the neuronal release of NO.

References:

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