Valeant has named Howard Schiller as a stand-in for chief executive Michael Pearson, who was hospitalised over the holiday period.
The appointment of Schiller - a former chief financial officer at Valeant - has dashed hopes that Pearson would make a speedy recovery. In his absence independent director Robert Ingram has taken over on an interim basis as chairman of the board.
In a statement, the company said that Pearson "remains in the hospital where he is being treated for severe pneumonia, and as the timing of his expected return is uncertain, he will be on a medical leave of absence until further notice".
Last week, the company said three directors - Rob Chai-Onn, Ari Kellen and Rob Rosiello - would hold the reins while Pearson recovered, but the company has clearly decided it needs someone who can step in for a longer term.
Formerly at Goldman Sachs, Schiller was CFO at Valeant between December 2011 and June 2015 and has been a member of the board since September 2012. Ingram has been serving on Valeant's Board since September 2010 and was the chairman of the company between December 2010 and March
"I appreciate the confidence the board has placed in me as I step into this role while Mike focuses on his health," said Mr Schiller. "Our future is incredibly bright and I am looking forward to working with the rest of the senior leadership."
Schiller's appointment will hearten investors in Valeant, which has been going through a difficult period after finding itself at the heart of a political scandal in the US over medicine prices as well as allegations - hotly disputed - that it had used mail-order pharmacy Philidor Rx to inflate revenues.
Company observers have suggested that the workload resulting from managing these issues - including the negotiation of a deal with pharmacy chain Walgreens after Valeant severed ties with Philifor RX - had taken its toll on Valeant's CEO.
The scrutiny of the company has made shareholders nervous and as a result shares in the company have lost almost two thirds of their value since last summer. Schiller's appointment helped steady the ship a little, with the stock rising 1.5% yesterday after the announcement.