AbbVie Inc (ABBV.N), the new branded pharmaceuticals company spun off by Abbott Laboratories Inc (ABT.N), is off to a good start, judging by fourth-quarter sales of arthritis drug Humira and other products in its medicine chest. The picture, although healthy, could be more challenging for the remaining Abbott, nicknamed “new Abbott,” which continues to sell medical devices, diagnostics, nutritional products and generic drugs, said analysts. The new Abbott said it expects earnings for 2013, excluding special items, of $1.98 to $2.04 per share, in line with its earlier guidance and above the average Wall Street forecast of $1.95. Although the company has not yet provided complete earnings data for full-year 2012, it said the mid-point of its 2013 profit forecast would likely represent double-digit earnings growth. But Abbott is still analyzing its numbers because of the split and may eventually restate some figures, analysts said. A big worry, according to Leerink Swann analyst Danielle Antalffy, is whether Abbott can revive sales of its branded generic medicines, which the company calls established pharmaceuticals. Sales of the products slipped 4 percent in 2012 to $5.1 billion. Abbott predicted they would capture mid-single-digit growth this year, excluding the impact of foreign exchange rates. “The business, which represents 25 percent of company sales, has been underperforming,” Antalffy said, adding that revenue forecasts for the business are difficult because they rely on data from so many local markets and countries.