Viagra had no effect on saquinavir pharmacokinetics. It is eliminated predominantly by hepatic metabolism mainly CYP3A4 and is converted to an active metabolite with properties similar to the parent, sildenafil. Your doctor will discuss the best treatment plan for you. A newer form of the medicine that dissolves on the tongue might work faster than the pill that you swallow. In healthy male volunteers, there was no evidence of a clinically significant effect of azithromycin mg daily for 3 days on the systemic exposure of sildenafil or its major circulating metabolite.About sildenafil (Viagra) Sildenafil is a medicine used to treat erection problems (erectile dysfunction). Sildenafil is also sometimes used to treat pulmonary hypertension (high blood pressure in the blood vessels that supply the lungs). If you have erection problems sildenafil works by temporarily increasing blood flow to your penis when. Sildenafil (Viagra). This medicine works best when you take it on an empty stomach an hour before sex. The body takes longer to absorb it after a high-fat meal or . Side effects: feeling hot & flushed. Tried 40 mg and was able to get fully hard but it took a little more stimulation. When wife was on top I it wasn’t as hard so we switched positions. Ejaculated after 30 minutes & had to wait an hour to get hard again before another 20 min of sex. No side effects with 40 mg.