Sen. Herb Kohl (D-WI), head of the Special Committee on Aging, is probing a drug company’s recent decision to restrict pharmacies’ access to the drug Avastin. The medication is used off-label for eye disease patients.

The company in question, Genentech, notified ophthalmologists that compounding pharmacies would not be allowed to purchase Avastin directly from wholesalers after Jan. 1. Kohl’s letter suggests Genentech’s goal may be higher sales for Lucentis, a similar but much more expensive drug it manufactures.

The eye disease use for Avastin (bevacizumab) is off label, or not formally approved by the Food and Drug Administration. However, some physicians have prescribed it to treat neovascular (wet) age-related macular degeneration. Avastin is approved by FDA to treat patients with certain forms of cancer.