Sanofi-Aventis SA announced Monday that it plans to buy U.S. health-care company Chattem Inc., maker of over-the-counter mainstays like Gold Bond skin products, for $1.9 billion in cash.

The move will make Sanofi-Aventis the fifth largest consumer health care company, up from sixth.

Chattem shares skyrocketed by $22.92, or 33 percent, to $92.90 in early trading after Sanofi-Aventis announced the $93.50 per share offer to acquire the company, a maker of consumer health care products such as Icy Hot pain relief medicine and Selsun Blue shampoo.

The deal is part of a strategy by Sanofi and other top pharmaceutical companies to diversify, particularly into areas with stable product revenue, as they face a wave of patent expirations in the next several years.

(thanks to AP)