Are any equivalents of viagra available in India?

Q: I understand viagra (sildenafil) has side effects such as headache and in rare cases it can lead to cardiac problems. Is there any other drug, which is equally effective but safe and free from these side effects? Please indicate the brand names of the same available in India. What is the normal dose equivalent to 25 mg of sildenafil?

A:Sildenafil (Penegra, etc.) belongs to a group of medicines called PD-5 inhibitors. They act by dilating the blood vessels and thus increasing the blood supply. Tadalafil (brand name: Zydalis) also acts in a similar fashion. Since their mode of action is same, by and large, side effects are also similar. Zydalis is available as 10 mg and 20 mg. The usual dose is 10 mg. Its duration of action is longer and its effect can last up to 24 hours.