GREG KELLER AP Business Writer PARIS (AP) — Sanofi-Aventis has halted work on three experimental drugs including a once-promising depression treatment in order to focus its research and development efforts elsewhere, the European pharmaceutical giant said Wednesday. The world's third-largest pharmaceutical firm by prescription sales said the decision to halt development of the three late-stage drugs followed a "comprehensive and rigorous" review of its R&D pipeline, which will also include axing several drugs in mid-development and six projects that were still in early stages, Sanofi-Aventis said in a statement. The Paris-based company announced the R&D shakeup alongside its first-quarter earnings, which showed net profit rose 19.1 percent in the period to euro1.58 billion ($2.1 billion), up from euro1.3 billion a year earlier. Sanofi-Aventis said the three late-stage trial drugs it was halting work on were Saredutant, AVE5530, and TroVax, the rights to which it will give back to Oxford BioMedica. Saredutant was being tested as a possible antidepressant, while AVE5530 was an experimental treatment for high cholesterol. TroVax is an experimental cancer vaccine. Another vaccine that had been in Phase III trials, called Unifive, has also been discontinued so that the company could focus resources on its Hexaxim vaccine. Decisions on whether to axe an additional four experimental drugs, including a vaccine for West Nile virus, will be made "in the next few months" on the basis of ongoing clinical trials, Sanofi-Aventis said. Sanofi-Aventis ranks third among the world's drug makers, behind Pfizer Inc. and GlaxoSmithKline PLC, according to figures provided by research group Datamonitor. During the first quarter Sanofi-Aventis saw sales of its seven so-called "flagship" drugs, including Lovenox, used against deep-vein thrombosis or blood clots, anti-stroke and heart attack medication Plavix and once-a-day insulin Lantus, rise 11.3 percent to euro3.42 billion. Overall sales, including vaccines, were up 2.5 percent in the quarter to euro7.1 billion. Sanofi-Aventis shares fell 6.7 percent during the first quarter. At midday Wednesday the shares were up 3 percent at euro42.88. Sanofi-Aventis has been on an acquisition streak in recent weeks, buying smaller drug makers in the Czech Republic, Mexico and Brazil as it seeks to refill a development pipeline that analysts see as woefully light on new drugs to replace those that will soon go off patent and face competition from cheaper copies. Most recently, Sanofi-Aventis agreed to pay $500 million for Brisbane, California-based BiPar Sciences, which is working on a new cancer treatment. Sanofi-Aventis said BiPar Science's experimental BSI-201 cancer drug was one of three new candidates to have entered clinical development. The R&D shakeup is among the first signals that Chief Executive Chris Viehbacher is stamping his authority on Sanofi-Aventis since taking over last December. While Viehbacher has so far focused on making small and medium-sized acquisitions, he is leaving his options open to make larger ones. Speaking last week in China, Viehbacher told reporters "I wouldn't restrict myself in terms of size. It's something we look at proactively." Meanwhile Sanofi-Aventis' rivals have been engaging in a massive round of consolidation. Switzerland's Roche Group bought the 44 percent of Genentech Inc. that it didn't already own for $47 billion, and Pfizer Inc. is buying Wyeth for $64 billion, while Merck & Co. is buying Schering-Plough Corp. for $43 billion.