The authorities said that it did not enhance the efficacy of the existing approved drug.

"After having considered the submissions submitted by the applicant in the hearing, the written submission and amended claims filed... it is hereby ordered that the invention disclosed and claimed in the instant application... is not considered as an invention under the provisions of the Act," said Mr Bharat N S, Assistant Controller of Patents and Designs, in an order.

He added, "I do not admit that the claimed compound has enhanced efficacy over the base compound...and hence not patentable under Section 3(d) of Patents Act... and I therefore, hereby refuse this Application."

Quoting a Supreme Court judgement, the order said that the applicant would have to establish the therapeutic enhanced efficacy of the claimed compound over the base compound.

This is the second time that the authorities have rejected the company's patent application. In October last year, the Intellectual Property Appellate Board (IPAB) set aside an order by the patent office which rejected Pfizer's patent for a new formula of the drug and directed it to re-consider the application.