The definition of 'patent' in the patent manual, 2008 by patent office, India reads:
A patent is granted as an exclusive right by the Government for an invention for a limited period of time in consideration of disclosure of the invention by an applicant. A patentee enjoys exclusive right to prevent a third party from an unauthorized act of making, using, offering for sale, selling or importing the patented product or process within the country during the term of the patent. A patented invention becomes free for public use after expiry of the term of the patent or when the patent ceases to have effect on account of non-payment of renewal fee.
Section 2 (f) of Patents Act, 1970 says ""exclusive licence" means a licence from a patentee which confers on the licensee, or on the licensee and persons authorised by him, to the exclusion of all other persons (including the patentee), any right in respect of the patented invention, and exclusive licensee shall be construed accordingly;"
Hence, patents on a new drugs (product patents) give a pharma company an artificial monopoly over a market (as long as the patent is alive).