Nortadalafil is demethyl Tadalafil, which is a PDE5 inhibitor, currently marketed in pill form for treating erectile dysfunction (ED) under the name Cialis; and under the name Adcirca for the treatment of pulmonary arterial hypertension. IC50 value: Ta

Providing storage is as stated on the product vial and the vial is kept tightly sealed, the product can be stored for up to 24 months.
Wherever possible, you should prepare and use solutions on the same day. However, if you need to make up stock solutions in advance, we recommend that you store the solution as aliquots in tightly sealed vials at -20°C. Generally, these will be useable for up to one month. Before use, and prior to opening the vial we recommend that you allow your product to equilibrate to room temperature for at least 1 hour.

[1]. Beghyn, et al. PDE5 inhibitors: An original access to novel potent arylated analogues of tadalafil. Bioorganic & Medicinal Chemistry Letters (2007), 17(3), 789-792. [2]. Daugan, et al. The discovery of tadalafil: a novel and highly selective PDE5 inhibitor. 2: 2,3,6,7,12,12a-hexahydropyrazino[1',2':1,6]pyrido[3,4-b]indole-1,4-dione analogue. Journal of Medicinal Chemistry (2003), 46(21), 4533-4542. [3]. Porst H, et al. Chronic PDE-5 inhibition in patients with erectile dysfunction - a treatment approach using tadalafil once-daily. Expert Opin Pharmacother. 2012 Jul;13(10):1481-94. [4]. Frey MK, Lang I. Tadalafil for the treatment of pulmonary arterial hypertension. Expert Opin Pharmacother. 2012 Apr;13(5):747-55.