Aptalis Pharma has been valued at over $3bn by TPG, which is working with JPMorgan Chase and Evercore Partners to look for a buyer.
Anonymous sources close to the sale process told Reuters that interested parties had been put off by the high price tag and that it is unclear if a deal will be done.
India's Sun Pharmaceutical Industries and North Caroline-based Salix Pharmaceuticals were said to have been interested in buy Aptalis, but have since pulled back.
Elan and Forest Laboratories are among others who also considered bidding for the pharmaceutical company earlier in 2013, said Reuters, but also pulled out.
While it is still unclear if there will be any deal with Aptalis, the Reuters sources speculated that TPG could consider alternatives such as an initial public offering or a dividend capitalisation.
TPG, which has has $56.7bn of capital under its management, merged Aptalis with Eurand Pharmaceuticals in 2011. In the following year, Aptalis posted $269m in gross earnings.
The move to sell Aptalis Pharma comes at a time when there are multiple deals taking place in the pharmaceuticals world.
According to a Mergermaket report, there were 101 deals worth $6.6bn in the pharmaceutical, medical and biotech sectors aggregated during the first half of 2013. The second quarter saw the highest number of deals in all these sectors.
Royalty Pharma mounted a hostile takeover attempt of Irish drug company Elan. However, Elan was acquired at the end of July by US drug maker Perrigo in a deal worth of $8.6bn.