Valeant Pharmaceuticals and GlaxoSmithKline have responded to a Food and Drug Administration request for more information on a potential epilepsy drug candidate, but did not provide more details Monday on the information they provided.

In December, the FDA declined to approve ezogabine for "non-clinical reasons". The drug was designed to treat patients who are already using one to three other epilepsy drugs.

Valeant is based in Mississauga, Ontario. GlaxoSmithKline has its headquarters in London.

Shortly after the FDA rejection, Valeant Chairman Bill Wells and Chief Financial Officer Peggy Mulligan resigned. Robert Ingram, a board member since 2003, was named chairman, and Philip W. Loberg, the company's senior vice president and corporate controller, took the role of CFO. He has been with Valeant since 2000.

In March, ezogabine was approved by European regulators under the name Trobalt.

Shares fell of Valeant Pharmaceuticals International Inc. $1.12, or 2.1 percent, to $52 in a broader market sell-off. The stock has traded between $18.07 and $55 over the last 52 weeks.

Shares of GlaxoSmithKline PLC fell 74 cents to $40.39.