Teva Pharmaceutical Industries has won a decision in the US District Court that should allow the company to begin marketing Prevacid (lansoprazole), a generic version of Takeda Pharmaceuticals' heartburn drug Prevacid SoluTab.
The court ruled that Teva's product used a different method to dissolve the treatment, and does not infringe another patent owned by French drug researcher Ethypharm SA and licensed to Takeda.
Teva has said that it will now complete an analysis of the decision before it proceeds with marketing the new generic.
Prevacid is believed to have generated sales of around $500m over 12 months ending June 2009.
Takeda may still decide to appeal the ruling.