This note begins by looking at patents issued by the USPTO that specifically mention the term ritonavir in the patent claims, or mention the NIH contract that was used to fund the early development of the product. This includes 194 patents that cite ritonavir in the patent claims, and another 42 patents that cite the NIH contact that funded the early ritonavir work. We also provide quotes from an August 19, 2011 WIPO report on the patent landscape for ritonavir that found 805 patent families related to ritonavir.

This is part of a what will be a larger submission to the United States Trade Representative (USTR), objecting to trade negotiations that seek to force developing countries to grant and enforce more types of drug patents than is required by the WTO. The most recent example of is the Trans Pacific Partnership Agreement (TPPA) negotiation, involving the governments of Brunei, Chile, New Zealand, Singapore, Australia, Malaysia, Peru, Vietnam and the United States. (More on TPPA here). In the TPPA, USTR has proposed this language:

"In addition, the Parties confirm that: patents shall be available for any new forms, uses, or methods of using a known product; and a new form, use, or method of using a known product may satisfy the criteria for patentability, even if such invention does not result in the enhancement of the known efficacy of that product."

The USTR text is a largely a reaction to 2005 India patent law amendments that limit the granting of patents. Section 3 of the India patent law sets out a list of non eligible patentable subject matter. Section 3(d) says:

“3. What are not inventions – the following are not inventions within the meaning of this Act, -
…
(d) the mere discovery of a new form of a known substance which does not result in increased efficacy of that substance or the mere discovery of any new property or new use for a known substance or of the mere use of a known process, machine or apparatus unless such process results in a new product or employs at least one new reactant.

Explanation: 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 substance shall be considered to be the same substance, unless they differ significantly in properties with regard to efficacy.”

USTR is seeking to prevent other countries from modifying statutes or practices along the lines of the Indian example, which has been very effective in limiting the evergreening of patent protection on drugs.

This note focuses on the proliferation of patents on ritonavir, to illustrate why the TPPA text is important.

Background

Abbott Labs developed ritonavir on a government grant. The drug is a protease inhibitor, and has the unusual property that it can boost the efficacy of other protease inhibitor drugs when used as part of 4-drug antiretroviral treatment regimes that also include 2 drugs from the Nucleoside Reverse Transcriptase Inhibitor (NRTI) class of drugs. Abbott offers a co-formulated version of ritonavir and lopinavir, another protease inhibitor invented on the same federal grant. Abbott has refused to license its patents to firms that want to co-formulate ritonavir with non-Abbott drugs.
Ritonavir was first registered with the FDA March 1, 1996. The earliest patent currently listed in the U.S. FDA Orange Book for ritonavir is US Patent No. 5,541,206, which was filed April 25, 1995 and granted July 20, 1996.