CVS Health Corp. dropped Pfizer's erectile dysfunction medication Viagra from its list of coverage for drug insurance benefits, two years before the treatment is expected to face generic competition.

Patients can get coverage for Eli Lilly & Co.'s Cialis instead, CVS said in a document detailing the drugs it is removing from the list, called a formulary, starting Jan. 1.

While CVS got its start as a discount retail chain, it has become increasingly influential in the drug business, acquiring Caremark in 2007 to become the second-biggest manager of pharmaceutical benefits on behalf of U.S. insurers and employers. That makes its coverage decisions important for drugmakers such as Pfizer, which analysts estimate will get $1.7 billion in sales from Viagra next year.

Press representatives at CVS and Pfizer did not immediately respond to requests for comment.

CVS's bigger competitor Express Scripts Holding will continue to cover Viagra and Cialis in 2016, according to the list it published this week.

Neither CVS nor Express Scripts cover Bayer AG's Levitra, the other major drug for erectile dysfunction.

— Bloomberg News