sildenafil [ 1-((3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo(4,3-d)pyrimidin-5-yl)-4-ethoxyphenyl)sulfonyl)-4-methylpiperazine citrate,Abbott brand of sildenafil citrate,Pfizer brand 1 of sildenafil citrate,Pfizer brand 2 of sildenafil citrate,Revatio,UK 92480-10,UK-92,480-10,Viagra,acetildenafil,desmethyl sildenafil,desmethylsildenafil,homosildenafil,hydroxyhomosildenafil,sildenafil citrate ] A 7,8-pyrazolo-pyrimidine, differing from PURINES which are 7,9-pyrazolo-pyrimidines; Viagra (tradename) is sildenafil citrate, used in oral therapy for male erectile dysfunction