Mallinckrodt dives as sales of main drug Acthar disappoint

Acthar - which contributes 42 percent to Mallinckrodt's overall revenue - generated sales of $308.7 million in the third quarter ended Sept. 30, missing analysts' average expectation of $326.6 million, according to brokerage Stifel.

The company said Acthar sales were likely to fall further in the fourth quarter from the third.

Acthar sales were dented by unfilled prescriptions, mainly due to reimbursement pressure from insurers.

"It could be because of the amount of hurdles that are put in place by the various payers (insurers), can be because of the amount of time it might take for these patients to get access to the products," Hugh O'Neill, president of Mallinckrodt's autoimmune and rare disease drugs business, said on a call with analysts.

The decline in Acthar sales volumes was likely to raise questions about a product that investors have shown an "unwillingness to give the benefit of the doubt," analysts at Barclays said.

Mallinckrodt's net sales fell 10.5 percent to $739.9 million in the third quarter, lagging analysts' estimates of $811.9 million, according to Thomson Reuters I/B/E/S.

Shares of the company, which have fallen 55 percent this year, were down 32.2 percent at $21.13 in morning trading on Tuesday.