hi kapil,
Data about estimated market size you can find in company announcement section at bse & nse sites. Also IMS gives details about it.
About competition, what i do is reading various brokerage reports, company presentations, and of course google.
Also sites like pharma compass, drugs.com can help you.
I suggest you to go through this thread…
ValuePickr Generics Pharma Dashboards - Focusing on asking the right questions!
regards,
Rakesh