Amino tadalafil is a potent inhibitor of phosphodiesterase 5 (PDE5).
PDE5, an enzyme found primarily in the smooth muscle of the corpus cavernosum, selectively cleaves and degrades cGMP to 5′-GMP. PDE5 inhibitors are similar in structure to cGMP and they competitively bind to PDE5 and inhibit cGMP hydrolysis, thus enhancing the effects of NO, resulting in prolonging an erection.
In vitro: Amino-tadalafil is a structural analogue of tadalafil, the active pharmaceutical ingredient in Cialis, a prescription drug approved in the US for treatment of erectile dysfunction (ED). Similarly, there have also been reports of herbal or dietary supplements being adulterated with designer ED analogues such as amino-tadalafil [1].
In vivo: In rats treated with both melatonin and tadalafil, the recoveries were more pronounced than in rats given either melatonin or tadalafil alone. The ICP/mean arterial pressure value in vehicle-treated rats was significantly higher than in the control group, while in the tadalafil- and tadalafil + melatonin-treated groups have returned this value had returned to control levels. In addition, as an individual treatment, and especially when combined with tadalafil, melatonin prevented spinal cord injury (SCI)-induced oxidative damage to cavernosal tissues and restored ED, most likely due to its anti-oxidant effects [2].
Clinical trial: Up to now, amino tadalafil is still in the preclinical development stage.
References:
[1] Hadwiger ME, Trehy ML, Ye W, Moore T, Allgire J, Westenberger B. Identification of amino-tadalafil and rimonabant in electronic cigarette products using high pressure liquid chromatography with diode array and tandem mass spectrometric detection. J Chromatogr A. 2010 Nov 26;1217(48):7547-55.
[2] Tavuk u HH, Sener TE, Tinay I, Akbal C, Er ahin M, Cevik O, Cadirci S, Reiter RJ, Sener G. Melatonin and tadalafil treatment improves erectile dysfunction after spinal cord injury in rats. Clin Exp Pharmacol Physiol. 2014 Apr;41(4):309-16.