BOSTON (MarketWatch) -- Drug stocks were slammed in afternoon trading Monday following U.S. House of Representatives' largely unexpected rejection of legislation to aid the the ailing U.S. banking industry. The Amex Pharmaceutical Index and the Amex Biotechnology Index both fell about 5% to 283.24 and 765.95, respectively. Gilead Sciences and Celgene Corp. were the biggest losers on the large cap biotech side, both dropping at least 13%. On the Big Pharma side, European drugmakers GlaxoSmithKline PLC , Novo Nordisk A/S and Sanofi-Aventis were the sharpest decliners, all down over 6%. ...