Polymorphs and Prodrugs and Salts (Oh My!): An Empirical Analysis of “Secondary” Pharmaceutical Patents

Abstract

BackgroundWhile there has been much discussion by policymakers and stakeholders about the effects of “secondary patents” on the pharmaceutical industry, there is no empirical evidence on their prevalence or determinants. Characterizing the landscape of secondary patents is important in light of recent court decisions in the U.S. that may make them more difficult to obtain, and for developing countries considering restrictions on secondary patents.Methodology/Principal FindingsWe read the claims of the 1304 Orange Book listed patents on all new molecular entities approved in the U.S. between 1988 and 2005, and coded the patents as including chemical compound claims (claims covering the active molecule itself) and/or one of several types of secondary claims. We distinguish between patents with any secondary claims, and those with only secondary claims and no chemical compound claims (“independent” secondary patents).We find that secondary claims are common in the pharmaceutical industry. We also show that independent secondary patents tend to be filed and issued later than chemical compound patents, and are also more likely to be filed after the drug is approved. When present, independent formulation patents add an average of 6.5 years of patent life (95% C.I.: 5.9 to 7.3 years), independent method of use patents add 7.4 years (95% C.I.: 6.4 to 8.4 years), and independent patents on polymorphs, isomers, prodrug, ester, and/or salt claims add 6.3 years (95% C.I.: 5.3 to 7.3 years). We also provide evidence that late-filed independent secondary patents are more common for higher sales drugs.Conclusions/SignificancePolicies and court decisions affecting secondary patenting are likely to have a significant impact on the pharmaceutical industry. Secondary patents provide substantial additional patent life in the pharmaceutical industry, at least nominally. Evidence that they are also more common for best-selling drugs is consistent with accounts of active “life cycle management” or “evergreening” of patent portfolios in the industry.

An Empirical Analysis of Primary and Secondary Pharmaceutical Patents in Chile

“…If the secondary patent offered exclusivity to some degree, would suggest that in some cases, companies could gain a number of additional years of patent exclusivity through the filing of secondary patents. The median number of possible additional Primary and Secondary Pharmaceutical Patents in Chile years is four, which is consistent with the numbers estimated by [9] for the United States. The active ingredient with the longest lag (15 years) is Posaconazole, an anti-fungal for which a crystalline form was patented in the United States 19 years after the original patent (see US patents 5278175 and 8435998).…”

TRIPS Implementation and Secondary Pharmaceutical Patenting in Brazil and India

“…WIPO data reveal an increase in secondary patenting worldwide over the [1996][1997][1998][1999][2000][2001][2002][2003][2004][2005][2006] period (Shadlen 2011, 148-149). In the US, the share of drugs approved by the FDA that include secondary patents has increased sharply since the 1980s (Kapczynski, Park, and Sampat 2012;Hemphill and Sampat 2011;Hunt 2002).…”

‘Pro et contra’ ionic liquid drugs – Challenges and opportunities for pharmaceutical translation

“…92 2. Classification of ionic liquids 93 ILs are organic salts composed of ionized species with a mp or 94 Tg lower than 100°C. Depending on the degree of ionization a dis- 95 tinction is made between the following species [5] ( Fig.…”

“…It has been estimated, that independent patents on salt 316 claims (or polymorphs, isomers, products, etc.) add an average of 317 6.3 years of patent life to a chemical compound patent[93].Thereby, ionic liquid approaches with rather uncommon or novel 319 counterions may substantially contribute to the ''evergreenin320 g''/life cycle management of pharmaceutical patent portfolios aim-321 ing to foster their monopoly status [94]. Similarly, new salts of an 322 API may be recognized as new chemical entities by the Food and Drug Administration (FDA) agency and other health authorities.…”