NEW DELHI: India's patent office has again rejected US drug major Pfizer 's new patent application for its rheumatoid arthritis medicine, tofacitinib, citing 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," Assistant Controller of Patents and Designs Bharat N S said in an order.The Intellectual Property Appellate Board (IPAB) in October last year 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."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," Bharat added in his order.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."For the purposes of this clause, salts, esters, ethers, polymorphs, metabolites, pure form, particle size, isomers, mixtures of isomers, complexes, combinations and other derivatives of known substances shall be considered to be the same substance, unless they differ significantly in properties with regard to efficacy," he said.When contacted, Pfizer said the company's base patent for Tofacitinib remains valid in India."Following this decision from IPAB, we are reviewing our options for further action," the company said.Pfizer remains committed to innovation and the long-term viability of its research and development programmes for the benefit of patients and healthcare practitioners in India and across the world, it said.The decision of the patent office assumes significance as multi-national drug companies have alleged that India's intellectual property rights (IPR) regime is not in compliance with the global norms.