Here is an article about a drug that was being developed.

I haven’t heard much about it recently, but the concept is interesting.

Phosphodiesterase type 5 (PDE5) inhibitors have reduced efficacy in treating erectile dysfunction (ED) in conditions where there is a lack of endogenous nitric oxide (NO). Therefore, NO-releasing PDE5 inhibitors have been developed. Here we report the effect of such a compound, NCX-911, on the tone and nitrergic relaxations of rabbit corpus cavernosum in the absence or presence of a NO synthase inhibitor, NG-nitro-l-arginine methyl ester (l-NAME; 500 muM). NCX-911 was found to be as potent as sildenafil at inducing relaxation of rabbit cavernosum (EC50 values 997.8plusminus195.7 and 1000.5plusminus140.8 nM, respectively). The potency of NCX-911 was not altered, but that of sildenafil decreased five-fold in the presence of l-NAME (EC50 values 1281.2plusminus268.3 and 4959.1plusminus882.1, nM respectively, P<0.001 for sildenafil). Both compounds potentiated nitrergic relaxations with similar potencies. These results suggest that NO-releasing PDE5 inhibitors could potentially be more useful than PDE5 inhibitors in the treatment of ED in conditions where there is a lack of endogenous NO.

From this link: ABSTRACT