MONTREAL – The disclosure by Valeant Pharmaceuticals International Inc. that it is under audit by the U.S. Internal Revenue Service is raising further doubts among tax specialists about the future of the Quebec-based drug company’s tax strategies. Valeant estimates it has achieved US$2.5-billion in tax and other “corporate structure” savings since merging with Ontario’s Biovail Corp.…

Valeant Pharmaceuticals under threat from tax audits, analysts say