The U.S. Dept. of Health & Human Services issued a subpoena to Novartis (NYSE:NVS) subsidiary Alcon Inc., seeking documents related to its marketing practices and payments to physicians.

The Sept. 23 subpoena is part of an HHS investigation probe into possible health care fraud, Novartis said in a regulatory filing.

"The subpoena requests the production of documents relating to the marketing practices as well as the remuneration of healthcare providers in connection with certain Alcon products (Vigamox, Nevanac, Omnipred, Econopred; surgical equipment)," according to the filing. "Alcon is cooperating with the investigation which is civil in nature."

Sign up to get our free newsletters delivered right to your inbox

Novartis closed its lengthy courtship of Alcon, now its second-largest division, in December 2010.

Alcon generated $2.49 billion in sales during the three months ended Sept. 30, up 118 percent compared with $1.14 billion during the same period last year.