Glenmark faces GSK patent challenge in US over malaria drug

Glenmark Pharmaceuticals today said its US subsidiary Glenmark Generics Inc USA, is facing a patent challenge by Smithkline Beecham Corporation (Glaxosmithkline) over its anti-malaria drug `Atovaquone' and `Proguanil Hydrochloride' tablets.

GSK has filed a lawsuit in the US court for the district of Delaware in connection with the abbreviated new drug application (ANDA) filing for `atovaquone' and `proguanil' hydrochloride 250mg/100mg tablets, Genmark said in a release.

GSK currently markets its product as Malarone in the US and is indicated for the prevention and treatment of malaria. The product had total US sales of approximately $53 million (as reported by IMS Health)  for the 12 month period ended June 2009.

"Glenmark believes it is the sole first to file applicant on this product, the company said in its release, adding, "Glenmark had earlier filed its ANDA containing a paragraph IV certification for its generic version of `atovaquone' and `proguanil hydrochloride' tablets with the US Food & Drug Administration (FDA), and following receipt of the notice from the FDA that Glenmark's ANDA had been accepted for filing, notified the New Drug Application (NDA) holder and patent owner."

"In the event that Glenmark successfully challenges the patent, Glenmark will be entitled to a 180-day exclusivity period", the company said in a release.

Glenmark has over 40 products authorised for distribution in the US marketplace. The company has also 45 ANDAs pending for approval with the US FDA. With this filing, Glenmark has four sole first-to-file products under litigation under the Hatch-Waxman Act. The other three products are Zetia (Ezetimibe), Tarka (Trandolapril + Verapamil) and Cutivate (Fluticasone lotion).