Valeant Pharmaceuticals International Inc. failed to provide satisfactory answers to an inquiry about its price increases for medications it acquired, Senator Claire McCaskill said.

The Missouri Democrat called the company’s response to her requests “deeply disappointing," in a letter published on her website on Monday. Valeant didn’t provide information on its expenses associated with two drugs, Isuprel and Nitropress, and didn’t give McCaskill a list of other medications whose prices have more than doubled, she said.

McCaskill pledged to continue investigating Valeant’s price increases and new allegations that have surfaced about its business model. The company is under scrutiny after a short seller raised questions about its relationship with a mail-order pharmacy Valeant has an option to acquire.

Valeant declined to comment. In its eight-page letter to McCaskill dated Oct. 14, the company said Isuprel and Nitropress were two of about 209 prescription drugs it sold, so it would be incorrect to draw conclusions from them. It said price increases are often whittled down in negotiations with insurers.

The drugmaker held a conference call Monday morning to mount a defense of the company’s arrangement to sell medications through the pharmacy, Philidor RX Services, explaining how it accounts for the inventory that moves through its business partner. The shares dropped 5.3 percent to $110.04 at the close, indicating investors remain skeptical.

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