The deal will see Medicure pay founding Apicore LLC shareholders C$24.5m ($18.9m) for an additional 32% stake in the firm, bringing its total holding to around 98%.
Apicore has two US Food and Drug Administration (FDA)-approved facilities, one in the US and one in Gujarat, India.
The US plant, in Somerset, New Jersey, has capacity to make 200kg of API per year, while the Vadodara facility can make up to 60 metric tons.
Manitoba, Canada-headquartered Medicure acquired a minority interest in Apicore in 2014 for C$1.3m in a deal that granted it the option to buy the API firm outright.
In December 2016, Medicure and Apicore submitted an abbreviated new drug application (ANDA) to the US Food and Drug Administration seeking approval for a “high-value” cardiovascular drug.