Shares of drug developer Sepracor ( SEPR) took a hit after the company reported disappointing sales. Sepracor fell 2.7% to $46.68. The top line of $264.4 million was an increase from $185.1 million last year, but it missed Wall Street's consensus target of $279.4 million. Earnings were $11.3 million, or 10 cents a share, compared with a loss of $7.4 million, or 7 cents a share, in the year-ago period. The latest second quarter included charges of $10.6 million, or 9 cents a share, for stock-based compensation. Analysts expected earnings of 9 cents in the second quarter. Nektar Therapeutics ( NKTR) fell 3.5% to $16.10 after research firm Miller Johnson initiated coverage of the company with a market-perform rating. Shares of HealthStream ( HSTM), the Internet-based health education and information provider, sank 10.3% to $3.30 a day after an announcement that its competitor WebMD ( WBMD) plans to acquire Medsite's medical education, promotion and physician recruitment businesses. Enzo Biochem's ( ENZ) shares fell after a court ruled that pharma-giant Roche didn't infringe its patents on a genetic information-detection technique. Enzo's shares were down 3.5% to $12. Amylin Pharmaceuticals ( AMLN) lost 7.4% to $45.76 after the stock was downgraded by Lehman Brothers to equal-weight from overweight. Amgen ( AMGN) was rising following a positive second-quarter earnings report after the close of trading Thursday. While the company took a significant charge related to the acquisition of Abgenix, excluding that and certain other items Amgen exceeded analysts' earnings estimates. Shares were up 3.9% to $66.41. Other health stocks on the move included Sunesis Pharmaceuticals ( SNSS), up 1.8% to $5, Aspreva Pharmaceuticals ( ASPV), rising 6.7% to $21.75, and orthopedic-implant maker Zimmer Holdings ( ZMH), adding 3.5% to $54.90. Novartis ( NVS) was up 1.4% to $55.10, GlaxoSmithKline ( GSK) rose 0.9% to $55.41, and Johnson & Johnson ( JNJ) was gaining 0.7% to $61.77. Teva Pharmaceutical ( TEVA) was down 1.6% to $29.73, Keryx Biopharmaceuticals ( KERX) was losing 2.2% to $11.18, Boston Scientific ( BSX) was off 1.3% to $15.77, Progenics Pharmaceuticals ( PGNX) was down 2.1% to $21.07, and Vertex Pharmaceuticals ( VRTX) was declining 2.3% to $34.17.