Atorvastatin (Lipitor): Pfizer succeded in patent re-examination of enantiomer patent

Innovator Pfizer announced that the USPTO has issued a “Notice of Allowance” accepting the company's application to correct the technical defect in the US5273995 enantiomer patent for atorvastatin calcium. The company noted that certain formalities must be completed before the reissue patent will be granted. The reissued patent will have the same force and effect as the original ˜995 patent and the same June 2011 expiration date.
There was technical defect in claim 2 of ‘995 patent which covers “[R-(R*R*)]-2-(4-fluorophenyl)-.beta.-.delta.-dihydroxy-5-(1-methylethyl)-3 -phenyl-4-[(phenylamino)carbonyl]-1H-pyrrole-1-heptanoic acid”.
The claim 6 of this patent covers “ The hemi calcium salt of the compound of claim 2 (covers Atorvaststin Hemicalcium specifically)”
The claim 6 was dependent on claim 2, however, claim 2 covers acid and not salts, accordingly, The US court in 2006 held the ‘995 patent’s claim 6 as invalid due to wrong dependency (as the claim 2 covers acid form of Atorvastatin and not salt). After realizing its mistake, Pfizer tried to correct the mistake by requesting patent office to reissue the said patent after correction. Further, patent office twice rejected pfizer’s reissue application (latest in April, 2008 as reported by us Here), however, Pfizer this time was able to convince patent office for reissue.
The said reissue allowance will further strengthen Pfizer’s strategy to keep off generic challenge.
Atorvastatin Litigation update in US
Para IV filers :
1.Ranbaxy (First para IV filer)
2. Teva
3. Cobalt
4. Apotex
Generic player in litigation: Teva and Apotex
Settlement: 1. Ranbaxy has settled its pending patent litigation on Lipitor (as reported earlier Here) and Caudet on June 18, 2008 and will launch its generic product in November, 2011.
2. Cobalt has lost its patent litigation on '995 patent with Pfizer. Cobalt filed 505 (b) (2) with Atorvastatin sodium. Cobalt has agreed to launch it’s generic version after the expiry of ‘995 patent
Orange Book Patents in litigation
US4681893 (Expiry: 24 March, 2010)- Covers racemic form of Atorvastatin generically. Litigation update: Ranbaxy was unsuccessful in invalidating the said patent in US Court of Appeals For Federal Circuit (CAFC) in 2006. Further, during recent reexamination of ‘893 by USPTO on request from a Law firm representing Ranbaxy, the USPTO as per their May 2008 decision upheld the validity of ‘893 patent.
Earlier, Teva and cobalt has filed Para III against this patent. Probably, Apotex has also filed Para III against said patent
US5273995 (Expiry: 28th June, 2011) - Covers Atorvastatin enantiomer and salts as Product (Specifically)
Litigation update: 1. The patent was invalidated by CAFC in August 2006 (Particularly claim 6 of this patent)
2. Pfizer applied for reissue of the patent to USPTO, which was rejected twice by USPTO. On April 2008, USPTO again rejected Pfizer request. Subsequently, the patent was allowed in modified form.
3. In Caudet litigation Pfizer stated that it had issued ‘covenant not to sue’ (will not sue Ranbaxy for the infringement of said patent) to Ranbaxy, in case ‘995 patent is reissued to Pfizer
4. Innovator Pfizer sued Cobalt and Teva for the infringement of ‘995 patent
5. On 15 May 2008, Court entered Judgment in favor of Pfizer and delayed Cobalt ANDA approval till expiry of ‘995 patent
6. On Dec 17, 2008, Innovator sued Apotex for the infringement of ‘995 patent
US5686104 (Expiry: 11th May, 2015)- Covers stable Formulation
Litigation update: Pfizer has sued cobalt but not asserted patent during trial
US5969156 (Expiry: 8th June, 2017)- Polymorph (Form I, II and IV)
Litigation update: Pfizer has sued cobalt but not asserted patent during trial
US6126971 (Expiry: 19th July, 2013)- Covers stable formulation
Litigation update: Pfizer has sued cobalt but not asserted patent during trial
Other patents
US6087511 - which covers a process for the preparation of amorphous Atorvastatin where crystalline Form I of Atorvastatin is dissolved in a non-hydroxylic solvent and after removal of the solvent affords amorphous Atorvastatin
Litigation update: Pfizer had sued Ranbaxy in March, 2008. However, in June 2008 Ranbaxy settled with Innovator on this patent
US6274740 - which covers a process for the preparation of amorphous Atorvastatin or hydrates thereof which comprises: (a) dissolving crystalline Form I Atorvastatin in a non-hydroxylic solvent at a concentration of about 25% to about 40%; and (b) removing the solvent by drying to afford said amorphous atorvastatin or hydrates thereof
Litigation update: Pfizer had sued Ranbaxy in March, 2008. However, in June 2008 Ranbaxy settled with Innovator on this patent