Zydus Pharma Inc, the US subsidiary of the Ahmedabad-based pharma major Zydus Cadila, has been sued by US major Wyeth, following the latter?s paragraph IV ANDA submission for the marketing approval of Effexor, a leading anti-depressant drug with $4 billion sales revenue, owned by Wyeth in the US market. A few Indian firms, such as Sun Pharma, Torrent Pharma and Dr Reddy?s Labs are in the race to get the marketing rights for Effexor, which will lose patent protection by 2010 in the US.
Wyeth has sued Zydus for alleged infringement of US patent for venlafaxine hydrochloride, the main ingredient in Effexor. In January this year, Wyeth had sued Torrent Pharmaceuticals? US subsidiary, Torrent Pharma Inc in the district court of Delaware, for alleging the infringement. A Spokesperson of Zydus Cadila said, ?As the matter is sub-judice, we cannot comment now.?
Once a generic firm files paragraph IV ANDA submission, the firm has to prove in court that its generic version will not infringe the patent of the innovator drug. The generic firm which wins the litigation will be eligible for market the drug exclusively for 180 days in the US.
Effexor is reported to increase the risk of suicide in anti-depressant patients. These suicide side effects include suicidal thoughts, suicidal gestures and attempts. The FDA in March 2004 issued a warning for Effexor and other antidepressants, such as Prozac, Paxil, Zoloft stating that the drug can cause suicide and violence in children and teenagers.
According to the lawsuit, Zydus filed an ANDA with FDA seeking approval to market venlafaxinc hydrochloride extended release capsules, copies of Wyeth?s Effexor XR capsules. ?Upon FDA approval of Zydus? ANDA, Zydus will infringe various patents of Wyeth, by making, using, offering to sell its venlafaxine hydrochloride ER capsules in the US,? the plaintiff said.
US patents, entitled ?Extended release formulation of venlafaxine Hydrochloride,? was duly and legally issued by the US patent and trademark office on August 14, 2001 and June 11, 2002 and July 16, 2002.
Wyeth, the owner by the assignment of the 171, 120 and 958 patents, has the right to sue for infringement thereof.
In a similar incident, Indian firm Natco Pharma Ltd was sued by Shire Canada Inc on April 1 in the district court of New Jersey, for alleged infringement of Shire?s Fosrenol (lanthanum carbonate chewable tablets, used for the reduction of serum phosphate in patients with end stage renal disease), following Natco?s filing of paragraph IV ANDA to manufacture the generic version.