THE patent battle between Pfizer Inc. and United Laboratories Inc. has moved beyond the courtroom and into the drugstore space, with Pfizer threatening legal charges against those that continue to sell Unilab?s Avamax.

Pfizer external legal counsel Esguerra & Blanco Law Offices on Oct. 7 sent letters to various drugstore chains in Metro Manila and the provinces, demanding that these stores stop selling Unilab?s generic version of Pfizer?s popular anticholesterol drug Lipitor.

Among the drugstores that received Pfizer?s demand letter were Watsons Personal Care Stores (Philippines) Inc., South Star Drug Inc., Amesco Drug in Davao City and Rose Pharmacy Inc. in Cebu City.

According to the letter, a copy of which was obtained by the Inquirer, Atorvastatin Calcium, the drug Pfizer marketed under the brand Lipitor and which Unilab started selling this month under the name Avamax, was still under patent with Warner Lambert, a company that Pfizer bought in 2004.

The letter said Warner Lambert continued to hold the patent for Atorvastatin Calcium and that Pfizer held its exclusive distribution rights in the Philippines.

?We demand that upon receipt of this letter, you immediately cease and desist from further distributing or selling these generic versions of Atorvastatin Calcium as you and your personnel are contributing to the infringement of valid and existing patent and exclusive distribution rights, thus causing grave and irreparable damage and injury to them,? the letter said.

?We likewise demand that you inform us in writing of your compliance with the foregoing, and of your willingness to execute an undertaking whereby you will forever desist from promoting, advertising, distributing or selling these generic versions of Atorvastatin Calcium within five days from receipt of this letter,? it added.

The letter said drugstores that would continue to carry Unilab?s Avamax would face legal action.

Asked for a response, Watsons senior regulatory affairs manager Belinda Pesayco said the drugstore chain had decided to continue carrying Avamax despite the warning as this provided a cheaper alternative to consumers taking anticholesterol medicine.

?Both Pfizer and Unilab are longstanding partners of ours in the business. But after thoroughly studying the matter, we decided to continue carrying Avamax because it is cheaper. We just want to fulfill what (RA 9502, or the Universally Accessible and Quality Cheaper Medicines Act) aims to do?to make affordable, good quality medicine accessible to as many consumers as possible,? she said in a telephone interview.