Mylan, Teva and Ranbaxy have each launched generic versions of Takeda's diabetes medication Actos in the lucrative US market.
Actos was one of Takeda's biggest performers, contributing annual sales of around $2.7bn. The market for type two diabetes medications is expected to nearly double by 2020.
The three companies launching the generic versions are sharing a 180-day period of exclusivity of the branded drug. Generic pharmaceutical company Watson had expected to also benefit from the exclusivity period, but the launch of its version was blocked by the US Food and Drug Administration (FDA).
The FDA forced Watson into submitting an abbreviated new drug application, which could lead to a six month delay, amid claims by Watson that the company was improperly denied. Watson has subsequently filed a lawsuit against the FDA.
The antidiabetic pill works by decreasing insulin resistance in diabetes sufferers, and is approved to aid glycemic control alongside diet and exercise in adults with type two diabetes.
Speaking on the launch of the generic copies, FDA Center for Drug Evaluation and Research Office of Generic Drugs director Dr Gregory Geba said; "Controlling blood sugar levels is very important in preventing or reducing the long-term health complications of diabetes."
"Generic versions of this widely used product will offer affordable treatment options for patients who must manage this chronic and potentially serious condition," Geba added.