Marion Merrell Dow Inc. reported that its...

Marion Merrell Dow Inc. reported that its profit plummeted 21% in the fourth quarter of 1993 and 47% for the year, as sales of its leading products continued to decline.

The pharmaceutical company said it earned $116 million, or 42 cents a share, in the quarter ended Dec. 31. That compared to $146 million, or 52 cents a share, in the year-earlier period.

Revenue fell 7%, from $797 million to $742 million. The acquisition of the Rugby Group, a generic drug company, added $82 million, preventing an even greater drop.

Among the leading products that lost sales, revenue from the line of Cardizem heart medication products products fell 21% in the quarter and 13% for the year--to $913 million.

For the full year, with a $180-million restructuring charge, net income was $362 million, or $1.30 a share, down from $685 million, or $2.44 a share, in 1992. Without the onetime, pretax charge, earnings declined 28% to $491 million, or $1.76 a share.

Revenue fell 15%, to $2.8 billion, from $3.3 billion in 1992.