MONTREAL -- Valeant CEO Michael Pearson said he's recovering from a severe bout of pneumonia but doesn't know when he will return to the embattled Canadian drug company.

In a memo to employees, Pearson, 56, said his hospitalization was longer than anticipated.

"I'm glad to say that I'm on the road to recovery and although the timing of my return remains uncertain, I look forward to being back at work when able," he wrote.

Meanwhile, interim CEO Howard Schiller's testimony to Congress that was scheduled for Tuesday has been postponed until Feb. 4 because of the weekend blizzard that struck the capital.

Valeant's (TSX:VRX) former chief financial officer and officials of other drug companies have been summoned to appear before a Republican-led House committee that is looking into a 76 per cent increase in the wholesale price of the 30 top-selling drugs between 2010 and 2014.