A deal is likely to be announced in the coming weeks, one of the sources said on Friday.
KKR India Chief Executive Sanjay Nayar declined to comment, while Gland Pharma Vice Chairman Ravi Penmetsa was not immediately available for comment.
The deal would be KKR's second sizeable India investment in six months. In April, it bought a controlling stake in India's Alliance Tire Group from Warburg Pincus LLC for what sources said was about $500 million.
Established in 1978, unlisted Gland Pharma makes active pharmaceutical ingredients and injectable formulations for segments including osteoarthritis, anti-coagulants, gynaecology, and ophthalmology, according to its website.
Private equity investments in India fell about 67 percent in the September quarter from a year earlier, to about $1.3 billion in 75 deals, according to early data from Venture Intelligence.