The London-based company, which won approval for the drug in the United States, called the problem temporary.
A deal between the two London-based companies would easily be the biggest.
The London-based company has sales of about £180 million a year and employs 400 people.
Since taking over Armchair in 2005, it has seen more cross-cooperation between the two London-based companies.
The London-based company is primarily known for its print design.
The London-based company would also assume $49 million in debt.
The results for the London-based company were lower than most analysts had expected.
The London-based company quickly rejected the offer of $:1.60, or $2.85, a share.
The London-based company said its American pharmaceutical sales were up 25 percent.
The merger of the two London-based pharmaceutical companies would dwarf most competitors.
