Schering Corp’s Patent Revoked in Cipla’s Post Grant Opposition by Chennai Patent Office

In a 20-page decision delivered on December 10, 2012 in a post-grant opposition filed by Cipla, the Chennai branch of the Indian patent Office revoked Schering Corp’s patent 246328 on “An aerosol suspension formulation for inhalation”. The patent was revoked for lack of inventive step.

The patented invention addressed issues related to use of non-CFC (Chlorofluorocarbons) propellants in pressurized aerosol formulations, such as the ones used in inhalers by Asthma patients. In particular, the patent addressed problems associated with use of HFA 227 (1,1,1,2,3,3,3-heptafluoropropane) and HFA 134a (1,1,1,2-tetrafluoroethane) as propellants in inhalers.

Following are certain extracts from the decision:

“From the above disclosure it can be concluded that both HFA 227 and HFA 134a are the propellants that can be used according to invention. Though HFA 134a has the disadvantage of settling the active drug it can be overcome by shaking the canister, hence the argument made by the agent for the Patentee that the Patentee has restricted to HFA 227 in the claims is not convincing.

Had the Patentee thought the HFA 134a cannot be used in the inventive formulations then the description and claims are not in inconsistent with each other? Use of both HFA 227 and HFA 134a not compatible with valve assemblies is concluded to be a known problem and the solution as discussed in the granted specification is also concluded as known solution and does not have any impact on the alleged invention.

Surprisingly in the entire granted specification no comparison has been provided by using a carrier and not using a carrier. As understood the problem to be solved by this patent is the elimination of CFCs from the process of preparing the aerosol suspension formulations. How this problem is related either to the presence or absence of a carrier? The granted specification has no answer for this question.

The entire granted specification addresses to the problems associated with using non-CFCs in the making of aerosol suspension formulations. These problems and the solutions were amply discussed in the cited documents filed by the Opponent. None of the documents i.e D1 to D6 and other documents had discussed on the effects of carrier or the problems that may arose in the absence of carrier.

Then what is the functional difference between a carrier and a propellant? A carrier in general parlance is defined as are substances that serve as mechanisms to improve the delivery and the effectiveness of drugs. Drug carriers are used in sundry drug delivery systems such as: controlled-release technology to prolong in vivo drug actions; decrease drug metabolism, and reduce drug toxicity.

The propellant in general parlance is understood as technically, is the general name for chemicals used to create thrust. A propellant, in other words, is a chemical which is used in the production of energy and pressurized gas that is used to create movement of a fluid or to generate propulsion.

By looking at a plain reading on the definitions, both the carrier and propellant are doing the same job. Though there is a difference in applications, it is needless to say that when drug has to be delivered in aerosol suspended form the propellant is the only option for intended use. Therefore in the present formulations the propellant is used for effective delivery. 

Hence the concept of the Patentee on claiming “substantially free of a carrier” is not understandable in the context of the proposed solution for solving the proposed problem. With respect to the combination therapy and the dosages fixed there is no inventive concept in the impugned patent.

Also there is no inventive step in the selection of non-CFCs for the preparation of the aerosol suspension formulation of the patent. There is no inventive concept on selecting HFA 227 and/or HFA 134a from known non-CFCs. There is no inventive concept on the preferential use of HFA227 over HFA 134a.  The claims are inconsistent with that of description as there is no comparative data with respect to the absence or presence of a carrier in the said formulations.

The claim 1 either on individual parameters or in its entirety lacks inventive step. Consequently the claims dependent on the claim 1 are not inventive. The sole process claim also in its entirety is not inventive as the said claim does not describe any inventive feature.

The descriptive portion of the specification does not throw any light on the carrier itself and hence based on the arguments during the hearing which were made around the presence or absence of a carrier is considered to be insufficiently disclosed.”