Drugmakers and biotechs may wind up spending more time and money to patent inventions under a new regulation proposed by the US Patent and Trademark Office. Under a proposed rule, each claim in a patent would be limited to a single invention and applicants who file a claim with alternative language would be encouraged to explain why the claim covers one invention, reports FDALegislativeWatch.com.

Inventors will be limited to two new continuing applications, through which they can add additional claims to the same patent, and only one request for a continued examination, which an inventor can file after the patent office has rejected his or her patent application, writes The Scientist. The rules, which will go into effect on Nov. 1, also restrict to 25 the number of claims in any single patent submission.

The new proposal is the latest effort by the PTO to reduce the burden on patent examiners by placing restrictions on what an inventor can submit to the agency, according to FDALegislativeWatch. In January 2006 the patent office published a proposed rule on continuing applications - in which an applicant adds new claims or disclosures to a previous application.

“This will disproportionately affect the biotech and pharmaceutical industries because typically this type of alternative claim language is the standard, accepted way their inventions are claimed,” Jessica Wolff, a patent litigator at Heller Ehrman, tells FDALegislativeWatch. Ron Eisenstein, a partner in the biotech and intellectual property group at Nixon Peabody, tells The Scientist that, “f all that the patent examiner has to say is no, it’s going to get much harder to negotiate, and will lead to applicants having to file costly appeals.”